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BMSC1214
Endcrinology
659
Pharmacology
Undergraduate 1
05/08/2016

Additional Pharmacology Flashcards

 


 

Cards

Term
What is the difference between primary and secondary endocrine glands?
Definition
primary glands secrete hormones as their primary function whereas secondary glands secrete hormones as the secondary function
Term
List some primary endocrine glands
Definition
Hypothalamus
Pit gland
Pineal gland
Thyroid
Adrenal
Parathyroid
Pancreas
Gonads
Placenta
Term
List some secondary endocrine glands
Definition
Heart
Kidneys
Liver
Stomach
Si
Skin
Term
Describe the endocrine action of hormones
Definition
1. Specialised cells in endocrine gland secrete hormones into circulation
2. Hormones are transported through the body
3. Target cells respond only to the hormone for which they have a receptor
Term
What does the concentration of a hormone in plasma depend on?
Definition
1. rate and pattern of secretion
2. rate of removal (eg metabolism or excretion)
3. degree of binding (eg plasma to protein) (ie free vs bound)
Term
What is hormone concentration useful for?
Definition
clinical diagnosis
Term
The release of most hormones in the body follow _____ patterns and is regulated by ________
Definition
pulsatile
stimulating/inhibitory feedback loops
Term
Describe a circadian rhythm and name 2 hormones that follow it
Definition
changes that follow a 24 hour cycle
cortisol and growth hormone
Term
Describe a ultradian rhythm and name 2 hormones that follow it
Definition
multiple release peaks in a day
Luteinizing hormone (LH) and Follicle stimulating hormone (FSH)
Term
What is a episodic pattern?
Definition
release in response to a particular stimulus
Term
What are the 3 classes of hormones?
Definition
1. Derived from amino acids (eg tyrosine)
2. Protein based hormones
3. derived from lipids
Term
Name some hormones derived from amino acids
Definition
Adrenaline and noradrenaline
Term
Name some protein based hormones
Definition
peptides and glycoproteins
Term
What does cholesterol produce?
Definition
steroids
Term
What does arachidonic acid produce?
Definition
eicosaniods (eg prostoglandins)
Term
What is the function of the thyroid?
Definition
to take iodine, found in many foods, and convert it into thyroid hormones: thyroxine (T4) and triiodothyronine (T3)
Term
How is T4 transported around the body?
Definition
T4 is lipophilic so it binds to plasma proteins
long half life (days)
Term
What hormones are derivatives of tyrosine?
Definition
- thyroid hormones secreted by thyroid gland (eg T4)
- catecholamines (eg adrenaline/noradrenaline and dopamine)
Term
Where is adrenaline/noradrenaline secreted from?
Definition
suprarenal medulla
Term
Where is dopamine secreted fro?
Definition
hypothalamus
Term
How are catecholamines transported around the body?
Definition
they are water soluble and transported in the blood
short half life (5-10mins)
Term
Give a derivative of derivative of tryptophan
Definition
melatonin which is secreted by the pineal gland
Term
Name some peptide derivatives
Definition
Glycoproteins: TSH, LH, FSH, EPO, inhibin
Short polypeptides and small proteins
Term
Where is TSH, LH and FSH released from?
Definition
pituitary gland
Term
Where is EPO released from?
Definition
kidney
Term
Where is inhibin released from?
Definition
reproductive organs
Term
Describe how a peptide/protein hormone is synthesised, stored and secreted?
Definition
1. activation of a gene followed by transcription and translocation of the protein and modification (in Golgi apparatus)
2. fully mature proteins are then 'packaged' into membrane bound vesicles
3. vesicles pinch off into either secretory or storage vesicles
4. they are released from the cell via exocytosis (Ca2+ dependent)
Term
Why are hormones stored this way?
Definition
to allow for rapid response to a stimulus
Term
Describe the events that follow an IV infusion of glucose
Definition
1. blood glucose levels rise much faster than oral admin
2. rapid ACUTE phasic release of pre-synthesised stored insulin from pancreatic beta cells
3. this is supplemented over time with the release of newly synthesised hormone in CHRONIC phase
Term
How long does the chronic phase last?
Definition
as long as the glucose challenge
Term
What happens to the inactive form of a hormone?
Definition
1. preprohormone is enzymatically cleaved at the Golgi apparatus
2. prohormone is enzymatically cleave din the storage vesicle
Term
What happens to the active form of a hormone?
Definition
active hormone is secreted cellularly and is followed by enzymatic cleavage into hormone derivatives
Term
What lipid derivative hormones are there?
Definition
1. eicosanoids (fatty acids derived from arachidonic acid)
2. steroid hormones (structurally similar to cholesterol) eg estradiol
Term
What eicosanoids are there?
Definition
leukotrienes
prostaglandins
thromboxanes
prostacyclins
Term
Where are steroid hormones secreted from?
Definition
adrenal cortex
gonads
placenta
Term
What are examples of steroid hormones?
Definition
estrogen and cortisol
Term
steroid hormones are ___ soluble
Definition
steroid hormones are lipid soluble and can therefore cross membranes easily
Term
How are steroid hormones stored?
Definition
They are not. They are secreted as they are produced "constitutive secretion" and are therefore not stored in vesicles
Term
Following a stimulus, how long does it take for steroid hormones detectable in plasma?
Definition
3-5 mins
Term
Following a stimulus, how long does it take for steroid hormones to achieve maximum secretion rates?
Definition
10-15 mins
Term
Describe steroidal affinity
Definition
Very high and are therefore very effective at low concentrations
Term
How do peptide hormones and catecholamines circulate in the body?
Definition
freely in the plasma
Term
How do steroid/thyroid hormones circulate in the body?
Definition
they are very hydrophobic and are carried in the blood bound to a variety of plasma proteins (eg albumin)
Term
Why do steroid/thyroid hormones have a longer lasting effect than peptide hormones?
Definition
Hormones bound to proteins are cleared from the circulation much slower. This creates a reservoir of hormone in blood, minimising hormone fluctuations and extending the half life of hormone.
Term
How long does bound T4 circulate for?
Definition
7-8 days
Term
How long does free T4 circulate for?
Definition
only minutes
Term
How are hydrophilic hormones transported and what is the benefit?
Definition
dissolved in blood plasma
free hormone is active form
eg epiphrene
Term
How are hydrophobic hormones transported and what is the benefit?
Definition
bound to plasma proteins
prolonged half life
eg T4 or cortisol
Term
What are the functions of binding proteins?
Definition
- help transport hormones and regulate the amount is biologicallt active
- permits delivery to target site
- protects hormones from degradation and excretion
Term
Hormones are inactive until...
Definition
...it dissociates from binding sites
Term
What are the general types of binding proteins and what do they transport?
Definition
plasma albumins transport large proteins (thyroid and steroid hormones)
transport globulins transport specifically (hormone binding proteins and steroid binding proteins)
Term
Describe the Michaelis-Menton kinetics of binding
Definition
Association and dissociation of the hormone-protein complex is in equilibrium set by the concentrations of free hormone and binding sites
Term
What does the equation KD = Kd / Ka mean?
Definition
overall rate of reaction = dissociation constant/association constant
Term
What can the Michaelis-Menton equation be used to calculate?
Definition
the conc of free hormone if the other parameters are known
Term
What is the significance of the free hormone?
Definition
- this is the concentration that is available for binding and regulates hormone release (via feedback control).
- the amount the can be cleared from the circulation by the kidney and liver
- the amount observed clinically in a case of over/underproduction
Term
How are hormones inactivated?
Definition
either by their target tissue or by metabolism (in the liver and kidney)
Term
What occurs to hormones that escape degradation?
Definition
excreted via the kidney into the urine except for hormones bound to plasma proteins (which cannot cross the renal filtration barrier)
Term
Describe the receptors for a lipid soluble hormone
Definition
inner or outer surface of the membrane
Term
Describe the receptors for a lipid insoluble hormone
Definition
on the outer surface of the membrane
Term
What must the hormone have if it does not have a direct action on the target cell?
Definition
a secondary messenger system (eg cAMP or Ca2+)
Term
What follows the diffusion of steroid hormones across the membrane?
Definition
1. diffusion through membrane lipids
2. binding of hormone to cytoplasmic/nuclear receptor
3. binding of hormone-receptor complex to DNA
4. gene activation
5. transcription and mRNA produced
6. translation and protein synthesis
7. alteration of cellular structure or activity
8. target cell response
Term
What follows the diffusion of thyroid hormones across the membrane?
Definition
1. transport across plasma membrane
2. bind to receptors on the mitochondria and nucleus
3. bidning of hormone-receptor complex to DNA
4. gene activation
5. transcription and mRNA produced
6. translation and protein synthesis
7. alteration of cellular activity/increased ATP production
8. target cell response
Term
What factors control hormone levels?
Definition
- rate of secretion
- amount of hormone transported bound to a carrier protein
- rate at which hormone is metabolised
Term
What is hormone release dependent on?
Definition
1. neural input
2. humoral input (blood bourne)
a) stimulatory
b) inhibitorary
Term
Describe the stress induced pathway that leads to the release of cortisol
Definition
1. stress causes neural signals to the hypothalamus
2. increased secretion of CRH hormone
3. anterior pituitory gland
4. increased ACTH secretion
5. adrenal cortex
6. increased cortisol secretion
Term
What are the 3 humoral signals?
Definition
hormones
ions
metabolites
Term
How do hormones stimulate hormone release?
Definition
- secreted form the hypothalamus or the anterior pituitary gland
- act to stimulate/inhibit release of other hormones
- negative feedback
Term
How do ions stimulate hormone release? EXAMPLE
Definition
eg blood potassium levels in the kidneys control the amount of aldosterone
Term
How do metabolites stimulate hormone release? EXAMPLE
Definition
eg glucose circulating in the blood determines the amount of insulin release by the beta cells in the pancreas to control blood glucose levels
Term
Define metabolic rate
Definition
the amount of energy expended per unit of time
Term
What is metabolic rate influenced by?
Definition
muscular activity
age
sex
body surface area
environmental temperature
Term
What does energy balance =
Definition
input - output
Term
What is BMR?
Definition
Basal Metabolic Rate
rate of energy expenditure of a person who is awake, lying down and mentally relaxed, fasted for 12 hours and in a thermoneutral environment (20 dc)
Term
What is oxygen consumption a measure of?
Definition
rate at which the individual is using oxygen (Lmin-1)
Term
What is the energy equivalent of oxygen consumption?
Definition
o2 for the food being metabolised (kJ per L of O2)
Term
How is metabolic rate obtained?
Definition
multiply by 60 (kJh-1)
Term
What is a spirometer?
Definition
instrument for measuring the air capacity of the lungs
Term
What factors affect basal metabolic rate?
Definition
body weight
body surface area (higher = higher as more heat is lost)
lean body mass (higher = higher)
age (increases = decreases)
sex (males are higher)
pregnancy (increase)
Term
What is the average metabolic rate?
Definition
20-25kcal per kg of body weight per day
Term
What factors affect general metabolic rate?
Definition
exercise
ingestion of food (protein increases)
fever
fasting and malnutrition
sleep
Term
What hormones affect energy metabolism?
Definition
catecholamines
thyroid hormones
growth hormones
male sex hormones
Term
How does our body know how to transition between the absorptive and the post absorptive state?
Definition
- under control of the endocrine system (mainly pancreas)
- islets of langerhans
- acini produces digestive juices
Term
What are the islets of langerhans?
Definition
The pancreatic islets or islets of Langerhans are the regions of the pancreas that contain its endocrine (i.e., hormone-producing) cells.
Term
What are the different islets of langerhans and what do they produce?
Definition
alpha = glucagon
beta = insulin
gamma = somatostatin
Term
What does insulin do?
Definition
promotes synthesis of energy storage molecules and other processes characteristic of the anabolic state. Plasma insulin levels trigger transition between anabolic and catabolic states
Term
Describe the insulin secretion mechanism
Definition
1. absorptive state
2. plasma glucose increases
3. plasma amino acid increases
4. increased GIP secretion
5. increased parasympathetic activity
Term
What do increased plasma glucose, plasma amino acid and GIP secretion cause?
Definition
pancreatic beta cells to secrete insulin
Term
What is glucagon secreted by?
Definition
alpha cells
Term
What does glucagon promote?
Definition
process of catabolism when plasma glucose decreases
Term
Describe the glucagon secretion mechanism
Definition
1. decreased glucose
2. increased plasma amino acids
3. increased sympathetic activity
Term
How are blood glucose levels controlled?
Definition
negative feedback with glucagon and insulin
Term
What is the desired blood glucose level?
Definition
70-140mgdL-1 (4-8mmolL-1)
Term
What happens if levels rise above 140mgdL-1?
Definition
hyperglycaemia (diabetes mellitus)
Term
What happens if levels fall below 60mgdL-1?
Definition
hypoglycaemia
Term
What do adrenal corticosteroids promote? glucose
Definition
glycogen production and maintain glycogen reserves
Term
What is growth hormone? glucose
Definition
an anti-insulin glucose-sparing agent
Term
What do catecholamines do? glucose
Definition
when levels fall below 4mmol-1 they can mobilise glucose for use by brain
Term
What do thyroid hormones do? glucose
Definition
enhance glucose metabolism, ensure glucose reserves are mobilised
Term
When is anabolic metabolic rate occurring?
Definition
during meals
Term
When is catabolic metabolic rate occurring?
Definition
between meals
Term
What controls the transition between anabolic and catabolic metabolic rate?
Definition
pancreatic hormones insulin and glucagon
Term
Glucose must be tightly regulated at ___ moles per L
Definition
4-8
Term
What does increased insulin secretion from pancreatic beta cells have an effect on?
Definition
most tissues
liver and muscle
Term
What effect does insulin have on most tissue?
Definition
increased glucose uptake into cells therefore decreased plasma glucose
Term
What effect does insulin have on liver and muscle?
Definition
increased glycogen synthesis
decreased glycogenolysis
therefore decreased plasma glucose
Term
What effect does insulin have on the liver?
Definition
decreased gluconeogenesis
therefore decreased plasma glucose
Term
What is diabetes mellitus?
Definition
excessive blood glucose by inadequate uptake by cells in body
hyperglycaemic
Term
What causes diabetes mellitus?
Definition
impaired insulin secretion
type 1 = beta cell destruction
type 2 = impaired beta cell function and insulin resistance
Term
Symptoms of diabetes mellitus:
Definition
increased thirst
increased urination
tired (no glucose storage)
weight loss
Term
Later symptoms of diabetes mellitus:
Definition
blurred visin
slow wound healing
general itching
Term
Describe type 1 diabetes
Definition
beta cell destruction
absolute insulin deficiency
auto-immune
idiopathic
Term
Describe type 2 diabetes
Definition
insulin independent
impaired insulin secretion and/or resistance to the action of insulin on target tissue
Term
What is gestational diabetes?
Definition
develops during pregnancy (can stop after birth or continue into type 2)
Term
What are the diagnosis measurements for diabetes mellitus?
Definition
urine glucose
blood glucose
glycated haemoglobin
glycated serum proteins
urine ketones
other blood metabolite/hormones
Term
How is type 1 diabetes managed?
Definition
optimised/intensive therapy
mimic exogenous insulin, administer around meal times
administered subcataneously
diet, exercise and education
Term
How is type 2 diabetes managed?
Definition
lifestyle modifications:
- restrict fat and energy intake
- encourage exercise
- stop smoking
Term
What are the 5 oral agents used to control Type 2?
Definition
sulphonylureas
thiasolidizediones
biguanides
alpha-glucosidase inhibitors
agents that reduce fat absorption
Term
How do sulphonylureas work?
Definition
increase insulin secretion
bind to receptor on beta cell, leading to closure of ATP-sensitive potassium channels.
Term
What are sulphonylureas associated with?
Definition
weight gain and beta cell failure
Term
How do thiazolidizediones work?
Definition
reduce insulin resistance. PPAR-y agonist. More costly.
Term
How do biguanides work?
Definition
reduces insulin resistance and can reduce hepatic glucose output
eg metformin
Term
How do alpha-glucosidase inhibitors work?
Definition
delay absorption of carbohydrates.
inhibit alpha-glucosidase and increase fibre in diet, can cause flatulance
Term
How do agents that reduce fat absorption work?
Definition
reduce weight
inhibits pancreatic lipase
serotonin and noradrenaline reuptake inhibitor
Term
Describe the mechanism of sulphonylureas
Definition
1. sulphonylureas binds to its receptor on the beta cell membrane
2. causes potassium channels to close
3. depolarisation
4. causes ca2+ channels to open
5. causes insulin release
Term
How do potassium channels close?
Definition
glucose molecule bind to a GLUT-2 receptor
Term
Describe the mechanism of TZDs
Definition
1. TZD enters cells and binds to PPAR-y (found in fat and liver cells)
2. these form a complex with RXR
3. leads to enhanced expression of insulin sensitive genes (eg GLUT4)
4. increase insulin sensitivity at target cell and enhance lipid storage
Term
What is the treatment of type 2 diabetes?
Definition
1. non pharmalogical therapy
2. singel oral agent
3. two oral agents
4. insulin and oral agent
5. full insulin replacement
Term
How does the body respond to hypoglycaemia?
Definition
glucagon released from alpha cells
increased gluconeogenesis and glycogenolysis
inhibition of insulin secretion
Term
What are the symptoms and treatment of hypoglycaemia?
Definition
- sweating, pounding heart, shaking, hunger, confusion, drowsiness, speech difficulty
- oral glucose (IV if unconscious)
- recovery in minutes
Term
What are the longterm consequences of diabetes?
Definition
- cataracts and retinography
- higher risk of heart attacks/CV diseases/gastro diseases
- prevents wound healing
- demyelination of nerve
- impaired kidney function leads to increased blood pressure
Term
How do retinal capillaries change during diabetes?
Definition
they are usually tight junctions however they widen and proteins can leak out
Term
What is diabetic nephropathy?
Definition
kidney disease caused by damage to the capillaries in the kidneys' glomeruli
Term
What are the effects of diabetic nephropathy?
Definition
- harder for kidneys to filter blood
- increased blood pressure and hypertension
- releases signalling pathways
- causes ECM accumulation
Term
What is diabetic neuropathy?
Definition
nerve damage caused by chronically high blood sugar and diabetes
occurs in patients in poorly controlled diabetes
Term
What are the effects of diabetic neuropathy?
Definition
uncomfortable symptoms in lowers legs
nerve conduction velocity is slowed at this time
distal symmetrical neuropathy
demylenination of the nerves
Term
What are the future directions in diabetes research and treatment?
Definition
- pancreas and islet cell transplantation
- stem cell therapy
- gene therapy
Term
How do genetics affect growth and development?
Definition
usually set the overall height, patterns and timings of growth spurts
Term
How does the environment affect growth and development?
Definition
mainly nutritional, although illness, trauma and even smoking can modify growth processes
Term
What can ultrasound technology measure?
Definition
- foetal growth throughout pregnancy
- abdominal circumference
- femur length
- biparietal diameter (ear to ear)
Term
____ weeks gestation shows the greatest increase in foetal length
Definition
16-20
Term
What changes occur during periods of growth?
Definition
- increase in size and number of cells in bodys soft tissue
- increase in length and thickness of bone
Term
What does bone act as a reserve for?
Definition
calcium for when plasma calcium declines
Term
What must bone be?
Definition
strong not brittle
Term
What gives bone its strength?
Definition
crystals of calcium phosphate-hydroxyapatite
Term
What kind of tissue is bone?
Definition
bone is a dynamic living tissue allowing it to regenerate in cases of fracture but also to let the bone develop and grow when under the influence of hormones
Term
What does bone consist of?
Definition
osteoblasts
osteocytes
osteoclasts
osteoid
calcium and phosphate crystals
Term
What do osteoblasts do?
Definition
secrete osteoid
Term
What are osteocytes?
Definition
mature bone cells
Term
What do osteoclasts do?
Definition
secrete enzymes for remodelling (breakdown bone tissue)
Term
What is osteoid?
Definition
organic matrix
Term
Describe how bone grows
Definition
1. skeleton is laid down as cartilage model
2. model replaced by bone (ossification)
Term
Where does growth stature largely occur?
Definition
through an increase in length of long bones in limbs
Term
Where does the addition of new growth material take place?
Definition
at the epiphyseal growth plates which lie between the main shaft of the bone and 2 ends
Term
What is the diaphysis?
Definition
main shaft of bone
Term
What is the epiphyses?
Definition
2 ends of bone
Term
What are the epiphyseal growth plates?
Definition
lie between the 2 stem cells (chondroblasts) lie between the plates
Term
What is calcification?
Definition
begins in the innermost layer, osteogenic cells differentiate into osteoblasts that secrete osteoid and lay down bone
Term
Where is growth hormone derived from?
Definition
the pituitary samototrophs
Term
What is GH secretion controlled by?
Definition
GHRH which stimulates output
somatostatin inhibits it
Term
Describe GH release pattern?
Definition
irregular pulsatile pattern of release influenced by physiological stimuli (eg stress, exercise and significantly deep sleep in children)
Term
What can stimulate early development in girls?
Definition
oestrogen
Term
What effect does insulin have on GH secretion?
Definition
decreases it
Term
What are the major metabolic effects of GH?
Definition
- opposes insulin effects
- acts on liver, muscle and adipocytes
- depresses glucose metabolism preserving for use by CNS
- stimulates lipolysis
Term
How does GH promote growth?
Definition
- acts directly on chondrocytes and increase rate of differentation and cartilage formation
- indirect effects using other growth fcators (eg IGF) which act on cartilage, fat cells, fibroblasts and humour cells
Term
What are the abnormal effects of GH secretion?
Definition
dwarfism
gigantism
acromegaly
Term
What causes dwarfism?
Definition
deficient secretion of GH
can be due to defective GH receptors
Term
What are the effects of dwarfism?
Definition
- stunting of growth
- poor muscle development
- higher than normal body fat
Term
What causes gigantism?
Definition
excessive secretion of GH before puberty
Term
What are the effects of gigantism?
Definition
abnormally large stature
Term
What causes acromegaly?
Definition
excessive secretion of GH in adulthood
from pituitary tumours
Term
What are the effects of acromegaly?
Definition
overgrowth of soft tissue and increase in bone circumference
Term
What other hormones affect growth?
Definition
thyroid hormone
corticosteroids
insulin
Vt D and parathyroid hormone
Term
What does Human Growth Hormone (hGH) do?
Definition
- grow in stature and bone growth
- orchestrate nutrient partitioning (moves energy to protein synthesis rather than fat)
Term
What are the actions of hGH?
Definition
- improves muscle definition
- elongate bone
- decrease glucose storage
- decrease fat storage
- decreases fat mass (adipose tissue)
- exercise has the effects of hGH levels
Term
How is hGH administered?
Definition
peptide injected synthetic
can be artificially stimulated
Term
Why do athletes abuse hGH?
Definition
- increase muscle mass and strength
- increase lean body mass
- improve appearance of musculature
- increase final adult height
Term
Where is the thyroid gland located?
Definition
on the ventral side of the trachea
Term
What hormones does the thyroid secrete?
Definition
T3
T4
calcitonin
Term
What do T3 and T4 do?
Definition
regulate the body's metabolic rate
Term
What is on the posterior side of the thyroid gland?
Definition
4 parathyroid glands that secrete parathyroid hormones
Term
What cells make up thyroid tissue?
Definition
follicular cells and parafollicular cells (c cells)
Term
What do follicular cells secrete?
Definition
iodine-containing thyroid hormones. They consist of thyroxine (T4) and triiodothyronine (T3)
Term
What do parafollicular (c) cells secrete?
Definition
calcitonin
Term
What do follicle cells surround?
Definition
a follicle cavity that holds a viscous colloid, a fluid containing a large quantity of dissolved proteins
Term
What globular protein do follicle cells synthesise?
Definition
thyroglobulin and secrete it into the colloid.
contains tyrosine
Term
How are iodide ions related?
Definition
they are absorbed from the diet and delivered to the thyroid
TSH sensitive carrier proteins on the basal membrane of the follicle cells transport iodide ions into the cytoplasm
Term
What is the fate of iodide ions in the cytoplasm?
Definition
they diffuse to the apical surface and lose an electron by thyroid peroxidase and attach to the tyrosine portion of a thyroglobulin molecule within the follicle cavity
Term
What is the fate of tyrosine molecules with attached iodide ions?
Definition
they become crosslinked by covalent bonds and form molecules of thyroid hormones that remain incorporated into thyroglobulin.
Term
How many iodide atoms does thyroxine and triiodothyronine contain?
Definition
4 (T4) and 3 (T3)
Term
What is the major factor controlling thyroid hormone release and why?
Definition
concentration of TSH in the circulating blood
TSH stimulates iodide transport into the follicle cells and stimulates production of thyroglobulin and thyroid peroxidase as well as thyroid hormone re;ease
Term
What events occur in the presence of TSH?
Definition
1. follicle cells remove thyroglobulin from the follicles by endocytosis
2. lysosomal enzymes break down the thyroglobulin and the amino acids and thyroid hormones enter the cytoplasm. amino acids are recycled and used to make more thyroglobulin
Term
Which is produced more T3 or T4?
Definition
T4 is produced at 10x greater rate than T3
Term
Which is more potent?
Definition
T3 is 4x more potent than T4
Term
What is the fate of secreted T4?
Definition
T4 secreted in plasma eventually converted by liver, kidney or target tissues to more active T3
Term
Describe the events that cause T3 and T4 secretion
Definition
1. stress or cold temp in children
2. hypothalamus increases TRH secretion
3. anterior pituitary increased TSH secretion
4. thyroid increased T3 secretion
Term
How is T4 controlled?
Definition
negative feedback loop between T4 levels and hypothalamus and anterior pituitary
Term
What effect does increased plasma T3 have on tissues?
Definition
- increased BMR
- increased heat production
- increased responsiveness to sympathetic input
- permits normal growth and development
Term
What effect does increased plasma T3 have on the nervous system?
Definition
- permits normal growth and development
- permits maintenance of normal activity
Term
How do thyroid hormones act?
Definition
1. thyroid hormone
2. intracellular receptor
3. transcription of specific genes
4. increased protein synthesis (cell growth and maturation)
5. increased cellular respiration
6. increased o2 consumption and metabolic rate
7. increased CO and ventilation and increased thermogenesis
Term
What do increased cell growth and maturation and increased cellular respiration cause?
Definition
increased food intake
Term
What are the effects of thyroid hormones on peripheral tissues?
Definition
- elevated rate of o2 and energy consumption
- increased HR and force of contraction (increased BP)
- increased sympathetic stimulation sensitivity
- maintenance of normal sensitivity to changes of o2 and co2
- stimulation of RBC formation and enhanced o2 delivery
- stimulation of activity in other endocrine tissues
- accelerated turnover of minerals in bone
Term
What are some thyroid gland disorders?
Definition
Hypothydroidism
Hyperthyroidism
Thyroid nodules
Term
What is hypothyroidism? give examples
Definition
underactive thyroid
- myxoedema: swelling of the skin
- hashimoto's thyroiditis: immune system attacks thyroid
Term
Common symptoms of hypothyroidism
Definition
fatigue
weight gain
feeling cold
dry skin and hair
heavy menstural periods
constipation
slowed thinking
Term
How is hypothyroidism diagnosed?
Definition
elevated level of serum TSH
Term
How is hypothyroidism treated?
Definition
replacement therapy
- thyroxine (oral)
- T3 (oral)
- thyroid hormone in pill form daily

overdose: angina and cardiac dysrhrythmia/hyperthyroidism
Term
What is hyperthyroidism? give examples
Definition
overactive thyroid
Graves disease
Term
Common symptoms of hyperthyroidism
Definition
jitterness/shaking
rapid heart beat
feeling hot
weight loss
fatigue
frequent bowel movements
shorter/lighter menstural periods
Term
How is hyperthyroidism diagnosed?
Definition
easily confused with other disorders if not diagnosed right away
analyse elevated level of free T4 and low level of TSH in the blood
Term
How is hyperthyroidism treated?
Definition
- surgical
- beta blockers eg propanolol
- antithyroid drugs
- iodide
- radioiodide
Term
Where is 99% of calcium found and in what form?
Definition
in bones in the form calcium phosphate (salt)
Term
How is calcium mobilised?
Definition
by hormones
Term
What is calcium important in?
Definition
teeth
connective tissue
blood clotting
functions like messenger systems
Term
What hormones control calcium?
Definition
Parathyroid hormone (PTH)
Calcitonin
Vit D (cholecalciferol) converted in calcitriol
Term
Where are calcitonin and PTH secreted from?
Definition
PTH from the parathyroid gland
Calcitonin from the thyroid gland
Term
What sites control calcium levels and how?
Definition
bones: release calcium into plasma or reabsorb
digestive tract: release more ca2+ from diet
kidneys: increase excretion/absorption
Term
What is the intracellular free calcium concentration
Definition
0.1 μmol L-1
Term
What is the total intracellular calcium concentration (free and bound)
Definition
2.3-2.4 mmol L-1
Term
What is the extracellular calcium conc?
Definition
1.4mmol L-1
Term
What factors increase blood calcium levels?
Definition
- PTH (with calcitriol
- PTH
Term
How does PTH (with calcitriol) control blood calcium levels?
Definition
higher concentrations increase rate of intestinal absorption and vice versa
Term
How does PTH increase blood calcium levels?
Definition
Bone: osteoclasts stimulated to release stored calcium ions from bone
KIdney: retain lost calcium ions
Term
What factors decrease blood calcium levels?
Definition
- decreased PTH (with calcitriol): rate of intestinal absorption decrease
- calcitonin
Term
How does calcitonin decrease blood calcium levels?
Definition
kidneys allow calcium loss
bone: osteoclasts inhibited while osteoblasts continue to lock calcium ion in bone matrix
Term
Where are the 4 parathyroid glands?
Definition
posterior to the thyroid
Term
Describe the cell types found in the parathyroid
Definition
Cheif/principle cells that secrete PTH and monitor Ca2+ levels
Oxiphil cells (function unknown)
Term
3 major effects of PTH:
Definition
Mobilises calcium from bone
Reabsorption of Ca2+ at the kidneys
Calcitrol at the kidneys
Term
Where is calcitronin released from?
Definition
c cells of the thyroid when Ca2+ levels rise
Term
How does calcitonin cause a drop in Ca2+ conc?
Definition
inhibition of osteoclasts
stimulation of ca2+ excretion at the kidneys
Term
What is calcitriol?
Definition
Calcitriol is a form of vitamin D. It works by promoting proper absorption and use of calcium and phosphate by the body in normal bone development and maintenance.

steroid hormone that works alongside PTH
Term
How is calcitriol initially synthesised?
Definition
from Vit D3 by 7dehydrocholesterol in sunlight
Term
How does calcitriol increase calcium levels?
Definition
- increases calcium levels by stimulating calcium absorption from digestive tract
- works on the distal tubule of the kidney to reabsorb ca2+
Term
Which foods are rich in vit d3?
Definition
mushrooms
certain oily fish (mackrel, salmon)
eggs
beef, liver
added to most western milk products
Term
What must be present for calcitriol to be synthesised in the kidney?
Definition
PTH
Term
What does calcitriol act on?
Definition
gut and kidneys
Term
Which hormone controls calcium absorption?
Definition
calcitriol
Term
Which hormones affect calcium blood levels using bone?
Definition
Calcitonin (calcification)
Resorption from bone to blood (PTH and calcitriol)
Term
How is calcium controlled by the kidneys?
Definition
filtered from the blood into the kidneys
PTH stimulated reabsorption into blood
Calcitonin inhibits reabsorption into blood
Term
At what serum calcium concentration would a patient be hypercalcemic?
Definition
2.2-2.6mmol L-1
Term
What are the causes of hypercalcaemia?
Definition
hyperparathyroidism
Term
What are the symptoms of hypercalcaemia?
Definition
fatigue
confusion
cardiac arrhythmias
calcification of kidneys and soft tissues
Term
What is the treatment of hypercalcaemia?
Definition
infusion of hypotonic fluid to lower ca2+ levels
remove parathyroid gland
administer calcitonin
Term
At what serum calcium concentration would a patient be hypocalcemic?
Definition
(<2.1 mmol L-1)
much less common
Term
What are the causes of hypocalcaemia?
Definition
hypothydoidism
under secretion of PTH
Vit D deficiency
chronic renal failure
Term
What are the symptoms of hypocalcaemia?
Definition
muscle spasms
convulsions
weak heartbeats
cardiac arrhtyhmias
osteoporosis
Term
What is the treatment of hypocalcaemia?
Definition
include calcium supplements
administer vit D
Term
What is phosphate balance linked to?
Definition
calcium due to bones
Term
Phosphate skeleton statistic pls...
Definition
740g of PO43- is bound in mineral salts of skeleton
Term
PO43- concentration of plasma is...
Definition
2.3 mmol l-1
Term
Where is phosphate reabsorbed?
Definition
kidney (proximal convoluted tubule)
Term
What is phosphate stimulated by?
Definition
calcitriol
Term
What are the causes of hyperphosphatemia?
Definition
high dietry phosphate intake
hyperparathyroidism
Term
What are the symptoms of hyperphosphatemia?
Definition
no immediate symptoms
chronic elevation leads to calcification of soft tissue
Term
What are the treatments of hyperphosphatemia?
Definition
with dietry reduction or PTH supplements
Term
What are the causes of hypophosphatemia?
Definition
poor diet
kidney disease
malabsorption syndrome
hyperparathyroidism
Vit D deficiency
Term
What are the symptoms of hypophosphatemia?
Definition
anorexia
dizziness
muscle weakness
cardiomyopathy
osteoporosis
Term
What are the treatments of hypophosphatemia?
Definition
dietry improvement
Vit D or calcitriol supplementation
Term
How does decreased Ca2+ affect phosphate via bone?
Definition
1. PTH secreted
2. osteoclast activity increases therefore increase blood phosphate conc
Term
How does decreased Ca2+ affect phosphate via kidney?
Definition
1. PTH secreted
2. phosphate secretion from renal tubules therefore decreased conc
Term
Therefore how does decreased ca2+ affect phosphate overall?
Definition
overall normal balanced conc
Term
Where is the pituitary gland ?
Definition
- pea sized structure that sits inferiorly to the hypothalamus
- near the optic nerve
Term
What does the pituitary gland form?
Definition
part of the posterior forebrain
Term
Where does the pituitary gland with respect to the pons?
Definition
anteriorly
Term
Where does the pituitary gland with respect to the forebrain?
Definition
inferiorly
Term
Where does the pituitary gland with respect to the hypothalamus?
Definition
inferiorly and is connected
Term
Where does the pituitary gland with respect to the sphenoid bone?
Definition
within the sphenoid bone in a cavity called sella tuncica
Term
What is the neurohypophysis also known as?
Definition
posterior pituitary
Term
What does the neurohypophysis consist of?
Definition
the median eminence (neural tissue of the hypothalamus), the posterior pituitary itself and infundibular system (which connects the two)
Term
What is the adenohypophysis also known as?
Definition
anterior pituitary
Term
What does the adenohypophysis consist of?
Definition
two portions:
- anterior pituitary itself (also called pas distalis)
- smaller pas tuberalis which wraps around the infundibulum
Term
What forms a boundary between the anterior and posterior pituitary?
Definition
- pars intermedia
- actively secretes MSH during development
Term
How does the pars intermedia change after birth?
Definition
regresses and may be absent in adult gland
Term
When does the pituitary develop?
Definition
third trimester of gestation
Term
Describe the basic development of the pituitary (4 steps)
Definition
1. roof of the mouth lies close to the 3rd ventricle of the brain and they bulge towards each other
2. buccal cavity (roof of mouth) bulges upwards to form Rathke's pouch
3. neural ectoderm bulges downward to form infundibulum
4. Rathke's pouch 'pinches off' and folds around the infundibulum
Term
Which tissue forms the posterior pituitary and which tissue forms the anterior pituitary?
Definition
Neural tissue forms posterior pituitary
Non-neural tssue forms the anterior pituitary
Term
What causes the anterior pituitary to release its hormones?
Definition
1. neurosecretory neurones in the hypothalamus release hormones into the hypophysial portal system
2. these stimulate the endocrine cells of the anterior pituitary to release hormones
Term
How many hormones does the anterior pituitary release?
Definition
6 peptide hormones
Term
What kind of blood supply does the AP have?
Definition
RICH
Term
Where does the AP receive its blood supply from?
Definition
the superior hypophyseal artery comes into the median emminence of the hypothalamus where the capillary bed is closely related to the neurosecretory neurones of the hypothalamus
Term
Where are hypothamic hormones released into?
Definition
the capillary bed and then carried to another set of capillaries in the hypothalamic-hypophyseal system (in the AP)
Term
What is the hypothalamic hypophyseal portal system?
Definition
The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is the transport and exchange of hormones to allow a fast communication between both glands.
Term
List the main hormones of the anterior pituitary gland
Definition
Growth hormone (GH)
Prolactin (PRL)
Thyroid stimulating hormone (TSH)
Follicle stimulating hormone (FSH)
Luteinizing hormone (LH)
Corticotropin related peptide hormones
Term
Where is GH synthesised?
Definition
by somatotroph and lactotroph cells

single peptide chain
Term
What are the effects of GH?
Definition
produces powerful effects on growth and metabolism in most peripheral tissues except CNS
Term
Where is PRL synthesised?
Definition
by somatotroph and lactotroph cells

single peptide chain
Term
What are the effects of PRL?
Definition
weak somatotrophic effects
promotes growth and maturation of mammary gland during pregnancy to prepare it for milk secretion
Term
What is the role of TSH?
Definition
glycoprotein hormone
regulates function of thyroid gland
Term
What are the roles of FSH and LH?
Definition
gonadrotrophic hormones
important roles in spermatogenesis by the testes and production of sex hormone in both sexes
Term
Name some corticotropin related hormones and how are they derived?
Definition
ACTH and MSH
derived from a single common precursor
Term
What controls the release of hormones from the anterior pituitary?
Definition
the hypothalamus
Term
Where are specific hormones of the anterior pituitary synthesised?
Definition
in the cell bodies of neurones in discrete areas of the median eminence
Term
Describe the hormone chain that releases thyroid hormones to target tissues
Definition
HH: Thyrotropin-releasing hormone (TRH)
APH: Thyroid-stimulating hormone (TSH)
Endocrine target: Thyroid gland
Term
Describe the hormone chain that releases cortisol to target tissues
Definition
HH: Corticotropin-releasing hormone (CRH
APH: Adrenocorticotropic hormone
Endocrine target: Adrenal cortex
Term
Describe the hormone chain that releases growth hormone to target tissues
Definition
HH: Growth hormone–releasing hormone (GHRH)
APH: Growth hormone
Endocrine target: Liver releases Insulin-like growth factor
Term
Describe the hormone chain that releases adrogens, estrogens and progesterone to target tissues and germ cells of the gonads
Definition
HH: Gonadotropin-releasing hormone (GnRH)
APH: FSH and LH
Endocrine target: Endocrine cells of the gonads
Term
Describe the hormone chain that releases prolactin the the breasts
Definition
HH: Prolactin-releasing hormone PRH and Thyrotropin-releasing hormone (TRH)
APH: prolactin
Term
What hormone inhibits the release of prolactin?
Definition
dopamine (PIH)
Term
What hormone inhibits the release of growth hormone?
Definition
Somatostatin, also known as growth hormone–inhibiting hormone (GHIH)
Term
Describe the negative feedback control of anterior pituitary hormones
Definition
1. hypothalamic releasing hormones stimulate release of AP hormones
2. this stimulates the release of a hormone from an endocrine organ
3. hormone released from endocrine affects it target organ
4. response is switched off by that endocrine organ inhibiting release of AP hormone and release of hypothalamic hormone
Term
How is the control of growth hormone different?
Definition
GH release is controlled by a releasing and inhibiting hormone
Term
What causes the posterior pituitary to release its hormone?
Definition
neurosecretatory neurones in the hypothalamus send axons into the posterior pituitary. They release hormones within the PP, directing into the blood stream.
Term
What hormones does the PP produce?
Definition
ADH (arginine vasopressin)
oxytocin
both nonapeptides
Term
How are PP hormones synthesised?
Definition
by magnocellular neurones in the the supraoptic (SON) and paraventricular nuclei (PVN) of the hypothalamus
Term
How are PP hormones transported?
Definition
in association with specific carrier proteins (neurophysins) along the axons of these neurones to the nerve terminals within the posterior lobe
Term
How are PP hormones released?
Definition
hormones are stored in secretatory granules either in terminals or in varicosities (Herring bodies) that are distributed along the axon. Hormones are released b ca2+ dependent exocytosis into the capillaries
Term
How do the structures of oxytocin (OT) and vasopressin (AVP) compare?
Definition
They only differ in their amino acid compositions at position 3 and 8
Term
What amino acid is at position 8 in AVP and which physiological action is this responsible for?
Definition
The arginine at position 8 in AVP is critical for its anti-diuretic action.
Term
What amino acid is at position 8 in OT and which physiological action is this responsible for?
Definition
The leucine substitution at position 8 in oxytocin does not remove all antidiuretic activity however, and at high doses oxytocin does stimulate water reabsorption by the kidney.
Term
How does desmopressin, a synthetic derivative, compare to vasopressin?
Definition
the N-terminal cystine is deaminated and the L-arginine at position 8 is replaced by the D form. These modifications extend the half life of the hormone when administered exogenously
Term
What causes release of vasopressin?
Definition
- increase in plasma osmotic pressure
- decrease in plasma volume (dehydration) detected by osmoreceptors in hypothalamus
Term
What receptors do ADH act on?
Definition
GPCRs: V1 and V2
Term
Where are V1 receptors found and what do they do?
Definition
in vascular smooth muscle where it stimulates contraction via phosphoionositide turnover thereby increasin intracellular ca2+
Term
Where are V2 receptors found and what do they do?
Definition
renal epithelial cells of the distal nephron to stimulate water reabsorption
acts via cAMP
Term
Describe the negative feedback system of ADH release
Definition
1. changes detected by osmoreceptors in hypothalamus
2. stimulates release of ADH from pituitary
3. leads to increased water reabsorption by the kidneys and plasma dilution
4. decreased osmolarity feeds back into hypothalamus to decrease ADH release
Term
What receptors does OT act on?
Definition
oxytocin receptors act via phosphoinosotide turnover and ca2+ in myoepithelial cells of the mammary gland to contract and cause milk ejection
Term
What role does oxytocin play?
Definition
- stimulates ejection of milk and may play a role in expelling the foetus and placenta during labour
- may play a role in erection, ejaculation and sperm progression
Term
What is the stimulus for oxytocin release?
Definition
- mechanical stimulation of the nipple (suckling)
- afferent info travels via the spinothalamic tract and brainstem
Term
What could abnormally high or low levels of a peripheral hormone be caused by?
Definition
1. the peripheral gland (primary endocrine disease)
2. the pituitary gland (secondary endocrine disease)
3. the hypothalamus (tertiary endocrine disease)
Term
What could one of the peripheral glands be?
Definition
thryoid
adrenal cortex
gonads
liver
Term
Why are primary deficiencies the most severe?
Definition
they involve complete absence of the peripheral hormone
Term
What does the hypothalamus and the pituitary control?
Definition
the normal secretion of thyroid hormones which in turn control metabolism
Term
Define hypothyroidism
Definition
the thyroid cells do not produce sufficient amount of thyroid hormone which causes a decrease in metabolism and a build up of metabolites
Term
What metabolites build up in hypothyroidism?
Definition
glycosaminoglycans (sugar and protein compounds)
Term
Where do glycosaminoglycans build up and why is this a problem?
Definition
they build up inside of various organs and tissues and cause an increase in water and mucus which forms oedema
Term
Describe the thyroid mechanism for the release of T3 and T4
Definition
1. hypothalamus releases TRH into portal system
2. TRH acts on the cells of the AP to release TSH which is transported via blood to the thyroid gland
3. thyroid releases T3 and T4
Term
What causes central hypothyroidism
Definition
Tumour: usually pituitary adenoma (congenital or aquired)
Radiation: causes damage to pituitary (usually caused by radiation therapy)
Vascular disease: eg Sheehan syndrome that results in reduced TSH
Term
What are some non-classic causes of hypothyroidism
Definition
traumatic brain injury
drug induced
growth hormone therpay
Term
What is central hypothyroidism a consequence of?
Definition
changes to the pituitary rather than the thyroid itself
Term
What would be the diagnosis if there were low T4 and low TSH levels?
Definition
secondary disorder (pituitary)
Term
Describe GH release
Definition
pulsative
during day and night
deep sleep is a potent stimulus to GH secretion
Term
What are the targets and effects of GH?
Definition
to oppose those of insulin
Muscle - decrease glucose uptake
Adipose tissue - increase lipolysis
Liver - increase gluconeogenesis
Combined - insulin resistance
Term
What characteristics do patients with GH-producing tumours have?
Definition
usually insulin resistant
glucose intolerant
possibly diabetic
Term
What does GH deficiency in children usually cause?
Definition
pituitary dwarfism
lack of GHRD or failure of IGF generation/action
Term
How does the role of IGF change through age?
Definition
During puberty there is a good correspondence between IGF and growth
In adulthood there is no longitudal growth, GH and IGF play a role in regulation of body mass (anabolism)
Term
How can GH secretion be tested?
Definition
administering a GHRH analogue to stimulate GH release from pituitary
(sermorelin)
Term
Describe the mechanism of GH release
Definition
1. GHRF released from hypothalamus (as is somatostatin)
2. Gh released from the pituitary
3. IGF-1 released from the liver to the peripheral tissue
Term
What does excessive GH release in children cause?
Definition
Gigantism
Term
What does excessive GH release in adults cause?
Definition
acromegaly
caused by a benign pituitary tumour
Term
How is the condition ameliorated?
Definition
- octreotide (a peptide analogue of somatostatin)
- bromocriptine (dopamine agonist)
- surgical removal or irridation of the tumour
Term
Describe the usual pathway for prolactin release
Definition
1. suckling
2. neural reflexes from the breast may initiate the release of a prolactin releasing factor (TRH?) for which there are mammatroph receptors
3. elevated levels of prolactin stimulate release of dopamine, which inhibits prolactin secretion
Term
Why is prolactin secretion from the AP unusual?
Definition
prolactin is subject to tonic inhibitory control by the hypothalamus. The inhibitory influence is via the so called dopaminergic-tuberohypophyseal pathway
Term
How can prolactin levels be increaseD?
Definition
by blocking dopamine receptors as prolactin release inhibition factor is dopamine
Term
What is GnRH?
Definition
gonadotrophin-release hormone
controls the release of gonadotrophins FSH and LH
Term
Describe GnRH secretion
Definition
controlled by neural input and by negative feedback of sex steroids by females
Term
What is gonadorelin?
Definition
synthetic GnRH
When given continuously they inhibit gonadotrophin release or if they are given in pulses they stimulate
Term
What do gonadrelin agonist treat?
Definition
endometriosis
short term: prevent endogenous ovulation (for IVF)
Term
What do gonadrelin antagonist treat?
Definition
used in oncology to reduce the amount of testosterone (prostate cancer)
Term
What is danazol?
Definition
a testosterone derivative that inhibits the release of gonadotrophins. It is used where decreased sex hormone production would be beneficial e.g. endometriosis
Term
What do clomiphene and cyclofenil do?
Definition
inhibit the release stimulate the release gonadotrophin release by antagonizing the negative feedback effects of androgens and oestrogen
Term
Generally what causes diabetes insipidus?
Definition
ADH deficiency
central vs nephrogenic
Term
What causes central diabetes insipidus?
Definition
loss of pituitary secretion of ADH
Term
How is central diabetes insipidus treated?
Definition
desmopressin (ADH analogue) whicih has higher V2 receptor selectivity and half life
Term
What causes nephrogenic diabetes insipidus?
Definition
impaired response to ADH at renal collecting duct
Term
How is nephrogenic diabetes insipidus treated?
Definition
fluid replacement until primary cause (eg effects of other drugs) are alleviated
Term
What is SIADH?
Definition
Syndrome of inappropriate ADH secretion
ADH secreting tumours, CHS disorders, pulmonary disorders and drug side effects
Term
How is SIADH treated?
Definition
Demeclocycline = tetracycline antibiotic that blocks ADH binding
Tolvaptan = unrelated V2 antagonist
Term
Name an oxytocin agonist and what it is used for
Definition
Carbetocin
used to induce/augment labour and treat post-partum haemorrhage
Term
Name an oxytocin antagonist and what it is used for
Definition
Atosiban and barusiban
reduce myometrial contractions and therefore treat preterm labour
Term
What does GH deficiency in children usually cause?
Definition
pituitary dwarfism
lack of GHRD or failure of IGF generation/action
Term
How does the role of IGF change through age?
Definition
During puberty there is a good correspondence between IGF and growth
In adulthood there is no longitudal growth, GH and IGF play a role in regulation of body mass (anabolism)
Term
How can GH secretion be tested?
Definition
administering a GHRH analogue to stimulate GH release from pituitary
(sermorelin)
Term
Describe the mechanism of GH release
Definition
1. GHRF released from hypothalamus (as is somatostatin)
2. Gh released from the pituitary
3. IGF-1 released from the liver to the peripheral tissue
Term
What does excessive GH release in children cause?
Definition
Gigantism
Term
What does excessive GH release in adults cause?
Definition
acromegaly
caused by a benign pituitary tumour
Term
How is the condition ameliorated?
Definition
- octreotide (a peptide analogue of somatostatin)
- bromocriptine (dopamine agonist)
- surgical removal or irridation of the tumour
Term
Describe the usual pathway for prolactin release
Definition
1. suckling
2. neural reflexes from the breast may initiate the release of a prolactin releasing factor (TRH?) for which there are mammatroph receptors
3. elevated levels of prolactin stimulate release of dopamine, which inhibits prolactin secretion
Term
Why is prolactin secretion from the AP unusual?
Definition
prolactin is subject to tonic inhibitory control by the hypothalamus. The inhibitory influence is via the so called dopaminergic-tuberohypophyseal pathway
Term
How can prolactin levels be increaseD?
Definition
by blocking dopamine receptors as prolactin release inhibition factor is dopamine
Term
What is GnRH?
Definition
gonadotrophin-release hormone
controls the release of gonadotrophins FSH and LH
Term
Describe GnRH secretion
Definition
controlled by neural input and by negative feedback of sex steroids by females
Term
What is gonadorelin?
Definition
synthetic GnRH
When given continuously they inhibit gonadotrophin release or if they are given in pulses they stimulate
Term
What do gonadrelin agonist treat?
Definition
endometriosis
short term: prevent endogenous ovulation (for IVF)
Term
What do gonadrelin antagonist treat?
Definition
used in oncology to reduce the amount of testosterone (prostate cancer)
Term
What is danazol?
Definition
a testosterone derivative that inhibits the release of gonadotrophins. It is used where decreased sex hormone production would be beneficial e.g. endometriosis
Term
What do clomiphene and cyclofenil do?
Definition
inhibit the release stimulate the release gonadotrophin release by antagonizing the negative feedback effects of androgens and oestrogen
Term
Generally what causes diabetes insipidus?
Definition
ADH deficiency
central vs nephrogenic
Term
What causes central diabetes insipidus?
Definition
loss of pituitary secretion of ADH
Term
How is central diabetes insipidus treated?
Definition
desmopressin (ADH analogue) whicih has higher V2 receptor selectivity and half life
Term
What causes nephrogenic diabetes insipidus?
Definition
impaired response to ADH at renal collecting duct
Term
How is nephrogenic diabetes insipidus treated?
Definition
fluid replacement until primary cause (eg effects of other drugs) are alleviated
Term
What is SIADH?
Definition
Syndrome of inappropriate ADH secretion
ADH secreting tumours, CHS disorders, pulmonary disorders and drug side effects
Term
How is SIADH treated?
Definition
Demeclocycline = tetracycline antibiotic that blocks ADH binding
Tolvaptan = unrelated V2 antagonist
Term
Name an oxytocin agonist and what it is used for
Definition
Carbetocin
used to induce/augment labour and treat post-partum haemorrhage
Term
Name an oxytocin antagonist and what it is used for
Definition
Atosiban and barusiban
reduce myometrial contractions and therefore treat preterm labour
Term
Where would you find the adrenal glands?
Definition
superior to each kidney
Term
Describe the arterial blood supply of the adrenal glands:
Definition
RICH
the superior, middle and inferior suprarenal artery
Term
Describe how blood returns to the systematic circulation
Definition
via a single suprarenal vein
Term
Where does the single suprarenal vein drain on the left?
Definition
into the renal vein
Term
Where does the single suprarenal vein drain on the right?
Definition
directly into the inferior vena cava
Term
Describe the blood flow of the adrenal glands
Definition
1. enters via the outer regions (cortex)
2. drain through the cortex into the venules
3. this flows through the innermost region (the medulla)
Term
What is the adrenal medulla derived from?
Definition
ectodermal cells of the neural crest
Term
Why can the medulla be considered part of the sympathetic division of the autonomic nervous system?
Definition
the cells of the medulla are modified sympathetic post ganglionic fibres
Term
What is the adrenal cortex derived from?
Definition
a different embryonic cell type – the mesoderm and is specialised for secretion of a number of steroid hormones
Term
In the foetus, what does the medulla secrete?
Definition
catecholamines in response to hypoxic stress and immediately after delivery in response to cold stress
Term
How does the adrenal gland differ in a foetus than in an adult?
Definition
1. the adrenal gland is much larger in relation to the foetal body size than it is in adult life
2. The foetal adrenal gland consists of three (rather than two layers)
Term
How is a foetal adrenal gland organised?
Definition
There is a small medullary region, a small zoned cortex – called the “definitive” cortex which is like that in the adult and a third, large zone known as the foetal zone.
Term
In the foetus, what is the role of the definitive cortex?
Definition
converts progesterone to cortisol especially during the last trimester of pregnancy
Term
How does the adrenal gland change after birth?
Definition
the foetal zone regresses rapidly and the definitive cortex and medulla enlarge to take on the structure and secretory roles of the adult gland.
Term
What is the role of the foetal zone?
Definition
produces the precursor molecules required for placental synthesis of oestrogens and its large size reflects the high levels of these steroids during gestation.
Term
What is cortisol important in?
Definition
- lung and liver maturation
- production of surfactant (lung inflation)
- triggering role in parturition
Term
In an adult gland, what are the zones of the cortex?
Definition
Zona glomerulosa
Zona fasciculata
Zona reticularis
Term
Describe the zona glomerulosa and its role
Definition
outermost zone which secrete (mineralocorticoid) steroids (eg aldosterone) that regulate mineral metabolism
Term
How can the role of the zona glomerulosa be remembered?
Definition
kidneys play an important role in mineral metabolism
glomerulus
zona GLOMERULosa
Term
Describe the zona fasculata and its role
Definition
middle zone which secretes glucocorticoid steroids that affect the metabolism of carbohydrates and to a less extent, fats and proteins
Term
Describe the zona reticularis and its role
Definition
innermost zone that is not fully developed until 6-7 years
secretes sex steroids
Term
What does the adult medulla secrete?
Definition
catecholamines:
- adrenaline (epinephrine)
- noradrenaline (norepinephrine)
- some dopamine
Term
Name some adreno-corticosteroids and what they are derived from
Definition
derived from cholesterol
- aldosterone
- cortisol
- sex steroids
Term
What does aldosterone target?
Definition
cells in the collecting duct and distal tubule of the kidney
Term
What does aldosterone regulate?
Definition
electrolyte balance and long term regulation of blood volume and pressure
Term
What are the effects of aldosterone?
Definition
- increase na reabsorption (and water) from kidney tubule
- increase k secretion
- increase h secretion
Term
Therefore, what is the effect of aldosterone on the urine?
Definition
more concentrated and acidic
Term
What does cortisol target?
Definition
many tissues: adipose, muscle and liver
Term
What does cortisol regulate?
Definition
metabolism of proteins, carbohydrates and fats
Term
What are the effects of cortisol?
Definition
- opposes the effects of insulin
- conversion of protein to glycogen (especially in muscle cells)
- increases amino acid supply to the liver for gluconeogenesis
- immunosuppressant, anti-inflammatory and anti-allergic
Term
How is aldosterone secretion controlled?
Definition
- levels of potassium acting directly on the adrenal cortex
- changes in plasma volume which is exerted via the renin-angiotensin system
Term
Describe the events that follow increased potassium levels
Definition
1. increased plasma K+
2. release of aldosterone from the cortex stimulated
3. excretion of k+ from the kidney
4. reduced plasma k+ = reduced secretion of aldosterone
Term
Describe the events that follow decreased blood volume/perfusion pressure
Definition
1. renin released from the juxtoglomerular apparatus
2. renin converts angiotensinogen to Angiotensin I
3. Angiotensin I converted to Angiotensin II in lungs
Term
What does Angiotensin II do?
Definition
Angiotensin II is a potent vasoconstrictor (increase pressure) and releases aldosterone to increase Na+ reabsorption to help increase plasma volume
Term
How is cortisol secretion controlled?
Definition
stress
ACTH is released from the AP gland and stimulates the release of cortisol
controlled by negative feedback inhibiting ACTH secretion
Term
What disorders are caused by corticosteroid secretion?
Definition
Cushings syndrome
Addisons disease
Hyperaldosteronism
Term
What are the causes of Cushings syndrome?
Definition
- overproduction of cortisol
- ACTH secreting tumour of the pituitary gland/adrenal gland
- long term use of glucocorticoids used to treat inflammatory conditions
Term
What are the physiological effects of Cushings syndrome?
Definition
- truncal obesity
- hyperglycaemia
- redistribution of body fat
- increased proteolysis = muscle wasting in proximal limbs
- enhances actions of catecholamines = hypertension
Term
What are the causes of Addisons disease?
Definition
- failure of the adrenal cortex to secrete both cortisol and aldosterone
- autoimmune disorder
Term
What are the physiological effects of Addisons disease?
Definition
- hypoglycaemia, loss of appetite and muscle weakness
- increased ACTH and CRH (due to loss of negative feedback) = hyperpigmentation
Term
What are the causes of Hyperaldosteronism?
Definition
- hyperplasia of cells in the zona glomerulosa (Conn's syndrome)
- aldosterone secreting tumours
Term
What are the physiological effects of Hyperaldosteronism?
Definition
- hypokalaemia
- sodium retention
- alkolosis
- hypertension
- low renin
Term
Explain how mineralocorticoid selectivity is enzyme based
Definition
- cortisol and aldosterone bind with equal affinity to receptor (MR)
- cortisol has higher plasma concentration
- MR enzyme (11βHSD2) converts intracellular cortisol to cortisone which has low affinity for the MR and generates high levels of NADH
- Generated NADH maintains cortisol–MR complexes in an inactive state and permits aldosterone to selectively activate the receptor, despite higher intracellular cortisol levels.
Term
How can inhibition of 11βHSD2 lead to hypertension?
Definition
Inhibitors of 11βHSD2 such as glycyrrhetinic acid, the active compound of licorice allows cortisol activation of MR, resulting in hypertension.
Term
What happens once a mineralocorticoid receptor complex is made?
Definition
translocates to nucleus and starts transcription
Term
What are the adrenals innervated by?
Definition
the thoracic sympathetic sypathetic chain
Term
Describe the innervation of the adrenal medulla
Definition
The sympathetic preganglionic fibres innervate (acetylcholine is the neurotransmitter) and stimulate chromaffin cells (which are essentially a specialised forms of sympathetic postganglionic fibre) in the medulla to secrete catecholamines.
Term
List the catecholamines released from the medulla
Definition
Epinephrine (80%)
Norapinephrine (20%)
Dopamine (<1%

ALL DERIVED FROM THE AA TYROSINE
Term
How is dopamine formed?
Definition
Tyrosine is hydroxylated to dihydroxyphenylalanine (DOPA) which is then decarboxylated to form Dopamine
Term
How is norapinephrine formed?
Definition
Dopamine is further hydroxylated to form norepinephrine (noradrenaline)
Term
How is epinephrine formed?
Definition
norepinephrine (noradrenaline) with the addition of a methyl group forms epinephrine (adrenaline).
Term
How are catecholamines released?
Definition
The chromaffin cells contain secretory granules containing one or other catecholamine and a variety of opioid peptides (enkephalins). Release into the blood stream is via exocytosis in response to acetylcholine release from sympathetic pre-ganglionic fibres.
Term
What receptors do medullary catecholamines bind to?
Definition
GPCRs with secondary messenger systems
alpha and beta
Term
Which shows higher affinity for norepinephrine and which epinephrine?
Definition
alpha = norepinephrine
beta = epinephrine
Term
What causes overproduction of adrenal catecholamines?
Definition
chromaffin tumour (chromaffinoma) known as phaeochromocytoma
Term
What does overproduction of adrenal catecholamines lead to?
Definition
Leads to severe hypertension, hyperglycaemia
Term
Name the 4 bones that makes up the pelvis
Definition
Left innominate
Right innominate
Sacrum: 5 fused vertebrae
Coccyx: 4 fused vertebrae
Term
What is each innominate made up of?
Definition
Ilium
Pubis
Ischium
Term
What are the pelvic divisions and what separates them?
Definition
Greater pelvis and lesser pelvis, seperated by the pelvic brim/inlet
Term
Name and describe the 3 parts of the unterine/fallopian tubes
Definition
Laterally (infundibulum)
Ampulla (usual fertilisation site)
Isthmus (narrow part)
Term
What are the 3 layers of the uterus?
Definition
Perimetrium
Myometrium
Endometrium
(out to in)
Term
What are uterine fibroids?
Definition
non cancerous uterine growths (variable size and location)
Term
When is the uterus usually damaged? and why
Definition
When pregnant.
Uterus enlarges and rises out of pelvis
can obstruct the inferior vena cava
Term
How does a mother adapt to prevent injury?
Definition
increased blood volume to protect from hypovolemic shock
uterus is thick and muscular and distributes force of trauma uniformally to fetus
Term
What are the male glands and what do they produce?
Definition
seminal vescile -> seminal fluid
prostate -> produces prostatic fluid
bulbaretural -> produces pre-ejaculate
Term
What is the spermatic cord and what does it include?
Definition
Attaches scrotum to the body
-ductus deferens
- blood vessels
-nerves
(enclosed in a muscular sheath)
Term
Describe the ejaculatory pathway
Definition

testes -> ductus deferens (and seminal vesicles) -> ejaculatory ducts -> prostatic/membranous urethra -> penis

 

TRAV picks up DANA AND SAM and EATS DOMINOS, they PULL UP at the MEET UP and PARTY

Term
Describe the composition of semen
Definition
Sperm (2-5%)
Semen (65-75%)
Prostatic fluid (25-30%)
Term
What is a TURP?
Definition
Used to cut off bad prostate
Resectoscope enters urethra and electrical currents heats the hoop to cut parts off.
Water is flushed through to remove pieces.
Term
How is the uterus supported?
Definition
via the broad ligament: a double layer of peritoneum draped over uterus and uterine tubes
Term
What does the broad ligament contain?
Definition
1) round ligament (uterus to labia majorum)
2) ovarian ligament (ovary to uterus)
3) suspensory ligament (ovary to laeral pelvic wall, contains ovarian vessels)
Term
What causes prolapse?
Definition
weakening of pelvic floor muscles or damage during childbirth
Term
List the erectile bodies of the penis
Definition
- corpus cavernosa (x2 dorsally)
- corpus spongium (ventrally)
Term
What are the 3 layers of the uterus (out to in)?
Definition
perimetrium
myometrium
endometrium
Term
What are the 4 parts of the uterus?
Definition
fundus
body
isthmus
cervix
Term
Describe the anatomy of the uterine/fallopian tubes
Definition
1. run from near the ovaries to the uterus
2. on the lateral part is the infundibulum (funnel shaped with fimbrae)
3. the ampulla
4. the isthmus
Term
What is the usual site for fertilisation?
Definition
the ampulla
Term
In males, what is the vesico-rectal pouch?
Definition
formed from the peritoneum (thin serous membrane) drapes over both the bladder and rectum
Term
What are the four parts of the male urethra?
Definition
1. pre-prostatic urethra
2. prostatic urethra
3. membranous urethra
4. spongy urethra (or penile urethra)
Term
What is the male reproductive system made up of?
Definition
testes
ductus (vas deferens)
seminal vesicles
ejaculatory ducts
prostate
penis
Term
What are the testes and what do they produce?
Definition
the male gonads and the produce germ cells and the hormone testosterone
Term
What is each testes suspended within?
Definition
the scrotal sac by the spermatic cord which contains the ductus (vas) deferens, blood vessels and nerves
Term
Describe the outer layer of each testis
Definition
Each testis has a tough fibrous outer layer known as the tunica vaginalis
Term
What does the tunica vaginalis enclose?
Definition
both the seminiferous tubules and the epididymis
Term
What happens once sperm have gained full maturity within the epididymis?
Definition
they enter the ductus (vas) deferens
Term
What is the ductus (vas) deferens?
Definition
a muscular cord with a thin lumen extending from te epididymis at the inferior pole of the testis
Term
How does the ductus deferens enter the body?
Definition
1. ascend within the spermatic cord
2. enters through the inguinal canal
3.
Term
Describe the route of the ductus deferens once it pierced the anterior abdominal wall
Definition
1. travels across the pelvic brim
2. runs along the lateral wall of the pelvis to join the seminal vesicle behind the bladder
3. this forms the ejaculatory duct
Term
Does the ductus deferens run over or under the uterior?
Definition
over
Term
What are the ejaculatory ducts formed by?
Definition
the union of the ductus deferens and the seminal vesicles at the posterior bladder neck
Term
Where do the ejaculatory ducts run and empty?
Definition
they run through the posterior aspect of the prostate
they empty its contents into the prostatic part of the urethra
Term
What is the function of the seminal vesicles?
Definition
Contains seminal fluid
Term
What is the function of seminal fluid?
Definition
1. rich in sugars (especially fructose), which feeds the sperm.
2. The fluid also has clotting properties that make the semen sticky. This ensures that the semen clings inside the vagina long enough for the sperm to travel to the egg.
Term
Where is the prostate gland?
Definition
sits inferiorly to the bladder with the prostatic urethra descending through it
Term
What do the prostatic ducts open into?
Definition
prostatic sinuses, either side of the seminal colliculus, which contain the openings of the ejaculatory ducts
Term
What is the function of the prostate?
Definition
The prostate secretes a milky substance that makes up around 20 to 30 percent of semen. It also has muscles that help to expel the semen during ejaculation.
Term
What would be the consequence of an enlarged prostate?
Definition
a doctor will schedule a manual rectal prostate exam if one of these disorders is suspected. The doctor will place his or her finger into your rectum and examine the prostate for unusual swelling.
Term
What procedure could reduce the size of a prostate?
Definition
TURP
Term
What happens to the erectile bodies during sexual arousal?
Definition
erectile tissues dilate and fill with blood causing the penis to become erect
Term
What does the female pelvis include?
Definition
the reproductive organs: vagina, uterus, uterine tubes and ovaries
Term
Describe the positioning of the vagina, uterus, bladder and rectum
Definition
the vagina and uterus are positioned between the bladder and rectum
Term
Describe the pouches in the female
Definition
a thin serous sheet, the peritoneum, drapes down from the abdomen and covers these organs forming two pouches: vesico-uterine and utero-rectal
Term
What is the vagina?
Definition
a musculo-membranous channel that extends from the vestibule, a cleft between the labia minora and the cervix
Term
How is the vagina normally?
Definition
collapsed
both the anterior and posterior walls are in contact except ath the superior limit of the vaginal canal where the cervix holds the walls apart
Term
What is the cervix?
Definition
a narrowing of the uterus that extends into the superior limit of the vagina, creating the fornix, a gutter around the protruding cervix.
Term
What is the posterior fornix?
Definition
the deepest of the fornices and is in close contact with the utero-rectal pouch
Term
How can the uterus be divided?
Definition
into a fundus, body and cervix
Term
What are the uterine walls composed of?
Definition
three layers (deep to superficial): endometrium, myometrium and perimetrium
Term
What does the uterus house?
Definition
the development of the embryo and foetus and provides muscular force during childbirth
Term
What orientation does the uterus assume?
Definition
anterverted - anteflexed so that the body lies over the superior aspect of the bladder
Term
What is a hysterectomy?
Definition
a surgical operation to remove all or part of the womb.
Term
Via which two surgical procedures can a womb be removed?
Definition
1. stomach sruger
2. vaginally
Term
Describe the ovaries
Definition
almond shaped structures that are responsible for the production and release of the female germ cells, the ova.
Term
How are ovaries suspended?
Definition
Each ovary sits in the lateral part of the pelvis and is suspended within the broad ligament by the suspensory and ovarian ligaments
Term
Describe the blood supply of the pelvis
Definition
by aorta which splits into external and internal iliac arteries
Term
Where are the female hormones secreted from?
Definition
Hypothalamus
Pituitary gland
Ovaries
Term
What is the first stage of the menstrual cycle?
Definition
mentruation - shedding of the uterine lining
Term
How many eggs are released per cycle?
Definition
1 egg at around the 14th day
Term
Define ovulation
Definition
the release of the egg from the ovaries
Term
Define atresia
Definition
the periodic process in which immature ovarian follicles degenerate and are subsequently re-absorbed during the follicular phase of the menstrual cycle.
Term
What is found within the ovaries?
Definition
follicles that are embedded within the connective tissue
Term
What is a primordial follicle?
Definition
- contains an oocyte in the middle
- contains a layer of epithelial cells around the outside known as follicle cells (which develop into granulosa cells)
Term
Define oocyte
Definition
a cell in an ovary which may undergo meiotic division to form an ovum.
Term
When does an epithelial layer become a granulosa layer?
Definition
when there is more than one epithelial layer
Term
What does a primordial cell become?
Definition
a theca cell (more mature and developed)
Term
List the stages of the ovarian cycle
Definition
1. follicular phase (first 14 days)
2. luteal phase (last 14 days)
Term
Describe the events of the follicular phase
Definition
1. begins with menstruation
2. ends with ovulation (release of egg into uterine tubes)
Term
Most follicles within the ovary are in the ____ phase
Definition
primordial phase
Term
What happens to the small remaining fraction of follicles?
Definition
they begin to develop independently of each other
Term
What do they develop into?
Definition
A preantral follicle
-granulosa cells surrounded by a layer of theca cells
Term
What does a preantral follicle develop into and how does this differ?
Definition
an early antral follicle
this contains a fluid filled cavity (antrum)
Term
What does an early antral follicle develop into and how does this differ?
Definition
the dominant follicle (the later antral follicle)
- the antrum has grown much bigger and is surrounding the oocyte
Term
Describe ovulation explicitly
Definition
The dominant follicle (at around 2cm diameter) bursts and releases the egg into the uterine tube
this is the beginning of the luteal phase
Term
What structure is left in the ovary after ovulation?
Definition
corpus leteum
Term
What causes the dominant follicle to burst?
Definition
- leutinising hormone (LH) increases
- releases proteolytic enzymes which ruptures the wall
Term
What is the fate of the oocyte if there is no fertillisation?
Definition
the corpus luteum structure lasts for about 10 days and causes the secretion of estrogen and progresterone
Term
What does the corpus luteum become if no fertillisation?
Definition
corpus albicans which causes a decrease om the secretion of estrogen and progresterone and hence stimulation of menstruation
Term
What is the fate of the corpus luteum if there is fertillisation?
Definition
The corpus luteum will persist as astructure and continue to stimulate the secretion of estrogen and progresterone
Term
What are the phases of the uterine cycle?
Definition
Menstrual phase (day 1-5)
Proliferative phase (day 5-14)
Secretory phase (day 14-28)
Term
What happens in the menstrual phase of the uterine cycle?
Definition
the shedding of the uterine lining
endometrial thickness decreases
caused by reduced levels of estrogen and progresterone
Term
What happens in the proliferative phase of the uterine cycle?
Definition
uterus renews itself in preparation for a potential pregnancy
Term
What causes the proliferative phase of the uterine cycle?
Definition
promoted by increase in estrogen caused by the development of the dominant follicle
- causes the development of blood vessels and nutrients in the uterus
Term
What happens in the secretory phase?
Definition
uterus is transformed in transformed into favourable place for implantation and potentially housing an embryo
Term
Name the 4 important hormones involed in the female reproductive cycle
Definition
LH
FSH
estrogen
progesterone
Term
Describe the changes in oestrogen levels over the female cycle
Definition
starts to peak just before ovulation then declines until just after and then raises again then drops (then starts to peak...)
Term
Describe the changes in progesterone levels over the female cycle
Definition
stays very low until the secretory phase where it peaks mid phase then declines again
Term
Describe the changes in LH and FSH levels over the female cycle
Definition
huge surge at period of ovulation (LH more)
Term
What events happen early to mid follicular phase?
Definition
1. FSH binds to receptors on granulosa cells (which causes growth and proliferation of the follicle)
2. Outer layer theca cells develop and gain more LH receptors
3. Dominant follicle secretes andorgens (specifically oestrogen)
Term
Describe the FSH feedback system
Definition
FSH binds to granulosa cells which release inhibin. Inhibin reduces FSH levels so that ovulation does not occur before the follicle is ready
Term
Describe the oestrogen feedback system
Definition
Affects the hypothalamus and anterior pituitary to control the levels of LH and FSH
Term
How is FSH released and what effect does it have?
Definition
1. Hypothalamus secrets GnRH
2. Anterior Pituitary secretes FSH
3. FSH binds to receptors on granulosa cells (which causes growth and proliferation of the follicle)
4. Controlled by negative feedback system of inhibin with the anterior pituitary
Term
How is LH released?
Definition
1. Hypothalamus secrets GnRH
2. Anterior Pituitary secretes LH
3. Acts on theca cells to cause oestrogen secretion
4. controlled by negative feedback with the anterior pituitary and hypothalamus to maintain oestrogen and LH levels
Term
Describe the hormonal changes in the late follicular phase
Definition
1. oestrogen acts on hypothalamus and AP (changes from negative feedback to positive feedback)
2. increases LH (mainly) and FSH levels
Term
What does oestrogen stimulate?
Definition
stimulates granulosa cells to express more LH receptors
Term
When is the LH peak?
Definition
a few hours before ovulation
Term
What secretes more oestrogen, the dominant follicle or corpus luteum?
Definition
dominant follicle
Term
Why does LH hormone decrease?
Definition
there is far less oestrogen and therefore no longer a stimulus for LH secretion
Term
What does the corpus luteum secrete?
Definition
1. inhibin (reduces FSH levels)
2. oestrogen (not much)
3. progesterone (uterus and breasts)
Term
How does preogesterone affect the uterus?
Definition
1. secretory phase changes
2. stops contractile activity (allows it to be a favourable place for implantation)
Term
How does preogesterone affect the breasts?
Definition
1. growth of glandular tissue
2. supression of lactation
Term
Describe the negative feedback system of progresterone
Definition
affects AP and hypothalamus
limits the growth of a new follicle as we don't known if the just released oocyte will be fertillised or not
Term
How does the uterus change during mensturation?
Definition
- endometrium thickens
- follicles secrete oestrogen
- increased number of glands and blood vessels
Term
How thick is the endometrium during ovulation?
Definition
2-3mm thick
Term
How does the uterus change during secretory phase?
Definition
- increased cellular proliferation
- secretion of hormones and cytokines
- increased lipids and glycogens (nutrients)
- increased blood supply
- corpus luteum secretes P and Oe
Term
How thick is the endometrium during the secretory phase?
Definition
it's thickest
4-6mm
Term
What causes menstruation?
Definition
decreased levels of oestrogen and progesterone
Term
Describe the events of menstruation
Definition
1. vasodilation (prostaglandin 2 alpha)
2. necrotic outer layers of the endometrium separate from the uterus
3. seperated tissue and blood initiate contractions
4. contents expelled
Term
The surge of LH mid ovarian cycle triggers...
Definition
..ovulation
Term
What events occur during the secretory phase, overall?
Definition
- fertillised ovum implants
- progesterone levels are high
- corpus luteum is formed
- endometrial glands enlarge
Term
How long does the sperm have to meet the ovum, post ovulation?
Definition
12-24 hours
Term
How long can the sperm live within the uterine tube for?
Definition
3-4 days
Term
Describe fertillisation
Definition
1. sperm and ovum meet in ampulla
2. sperm binds to receptors on membrane
3. oocyte will transport sperm into cyotplasm
4. sperm disintergrates and releases chromosones into cytoplasm
5. chromosomes combine
6. zygote formed
Term
What happens to the zygote?
Definition
1. undergoes mitotic division
2. becomes a blastomere and then a morula
Term
Describe a morula
Definition
3-4 days post fertillisation
contains about 16 blastomeres
Term
Describe a blastocyst
Definition
4-5 days post fertillisation
contains a fluid filled cavity
this moved down the uterus and implants 6 days post fertilisation
Term
When is the term embryo used?
Definition
between 2 and 7-8 weeks post fertillisation
Term
What forms the placenta?
Definition
trophoblastic cells invading the endometrium
Term
How long is the average pregnancy?
Definition
279 days is the peak
Term
How does the embryo receives its nutrients in the early stages of pregnancy?
Definition
the endometrium (later on it receives it from the placenta)
Term
How can a baby and a mother have different blood types?
Definition
Their blood never mixes.
The maternal vessels run very close to the placenta and the fetal blood vessels run into the placenta.
Term
Describe the changes in hCG secretion
Definition
- begins at implantation and increases for the first 3 months of pregnancy
- similar structure to LH
Term
Where is hCG produced?
Definition
- produced by trophoblast cells
- autonomous (not hypothalamus or AP)
Term
Describe the changes in oestroegn and progesterone secretion
Definition
continue rising until parturition
Term
Describe Human Placental Lactogen
Definition
polypeptide hormone secreted in increasing concentrations during pregnancy
Term
What are the effects of Human Placental Lactogen
Definition
1. stimulates lipolysis in the mother
2. inhibits glucose uptake in the mother
3. promotes the growth and differentiation of the breasts
Term
What forms does oestrogen come in in pregnancy and where are they produced?
Definition
- oestradiol produced by the corpus luteum and the placenta
- oestriol produced by the foetus and the placenta
Term
What are the effects of oestrogen in early pregnancy?
Definition
1. growth/strength of the myometrium
2. increases contractile proteins to accomodate the growing fetus in the female
Term
What are the effects of oestrogen in mid pregnancy?
Definition
to increase the blood flow to the placenta to help exchange nutrients/waste products
Term
What are the effects of oestrogen in late pregnancy?
Definition
1. part of the multi-hormonal increase
2. preparation of breasts for lactation
3. increases sensitivity of the uterus to contractile proteins (for labour)
Term
What is the role of progesterone during pregnancy?
Definition
- inhibits uterine smooth muscle contractility (oestrogen is the antagonist)
- keep uterus quiescent during pregnancy
- inhibits production of contractile proteins so labour doesn't occur early
Term
How does progesterone affect immunity?
Definition
inhibits T cell mediated responses (as foetus is 'foreign'
Term
When is prolactin released?
Definition
after birth to stimulate lactation
spiked
Term
Name the 4 parts of the male reproductive system
Definition
Testes
External genitalia
reporductive tract
accessory glands
Term
Name the male external genitalia
Definition
penis and scrotum
Term
Name the male accessory glands
Definition
seminal vesicles
prostate gland
bulbourethral gland
Term
What is the role of the penis?
Definition
Penetrates vagina and deposits sperm
Term
What does the penis undergo during sexual arousal?
Definition
Erection:
- Blood flow to penis increases
- Engorges erectile tissue
- Penis swells and elongates
Term
What is the role of the scrotum and where is it?
Definition
Suspended beneath penis
Houses testes
Sperm cannot develop at body temperature
Allows a cooler environment for sperm development
Term
How many compartments do the testes have?
Definition
250-300
Term
What are the testes encapsulated in?
Definition
a layer of fibrous connective tissue
Term
What is found in each compartment?
Definition
highly coiled thin tubules (seminiferous tubules)
this is where sperm is produced
Term
What cells are there in the testes?
Definition
Leydig cells (secrete hormones eg testosterone)
Term
What cells make up the seminiferous tubules?
Definition
there is an outer layer of smooth muscle then sertoli cells then lumen
Term
Where would you find the more mature sperm?
Definition
the lumen of the tubules
this is filled with fluid
Term
What is the role of the smooth muscle cell layer?
Definition
exhibit peristaltic contractions will help propel sperm and fluid along this highly coiled tubes
Term
Where are tight junctions found and why?
Definition
between the epithelial (sertoli) cells
they form the blood testes barrier
Term
What does the blood testes barrier separate?
Definition
this isolates the lumenal fluid from the spermatagoa
as sperm only contains 23 chromosomes the body would attack it if the barrier didn;t protect it
Term
What are the functions of Sertoli cells?
Definition
- support sperm development
- secrete several important things
- target cells
Term
What do Sertoli cells secrete?
Definition
- luminal fluid in which sperm develop
- androgen-binding protein
- inhibin
- Mullerian inhibiting substance (MIS)
Term
What is the significance of inhibin secretion?
Definition
hormone of negative feedback loop for FSH
Term
What are Sertoli cells targets for?
Definition
testosterone and FSH
they secrete chemicals that stimulate spermatogenesis
Term
Describe the reproductive tract
Definition
1. sperm develops in the seminiferous tubules
2. Rete testis
3. Efferent ductules (exits testis)
4. Epidiymis (larger tube with thicker walls)
5. Vas deferens (into pelvic cavity)
6. two vas deferens near the seminal vesicles
7. ejaculatory duct (converge)
8. passes through the prostate gland
8. urethra (via bulbourethral glands)
Term
What do the seminal vesicles secrete?
Definition
alkaline fluid with fructose, enzymes and PGs
Term
What does the prostate gland secrete?
Definition
secrete citrate (energy) and enzymes and prostate specific antigen (PSA)
Term
What does the bulbourethral gland secrete?
Definition
viscous fluid with mucus
Term
What can prostate specific antigen be monitored for?
Definition
prostate cancer
Term
Which male sex hormones are released from the AP and how?
Definition
1. hypothalamus
2. GnRH secretion
3. Anterior pituitary
4. FSH and LH secretion
Term
Where does FSH have an affect?
Definition
Sertoli cells. Causes:
- inhibin secretion
- spermatogenesis
Term
How are FSH levels controlled?
Definition
Inhibin controls via negative feedback to the AP
Term
Where does LH have an affect?
Definition
Leydig cells. Causes testosterone secretion which affects Sertoli cells
Term
How are LH levels controlled?
Definition
Negative feedback for AP and hypothalamus
Term
What are the effects that androgens (testosterone) has on various tissue targets?
Definition
1. maintenance of accessory reproductive organs
2. maintenance of secondary sex characteristic
3. increase sex drive
4. increased protein synthesis in skeletal muscle
5. increased bone growth in adolescence
Term
What are the 3 parts of the sperm?
Definition
Head
Midpiece
Tail
Term
What does the head of the sperm contain?
Definition
Chromosomes
Acrosome (which contains enzymes necessary for fertilisation)
Term
What does the midpiece contain?
Definition
mitochondria (produces ATP)
Term
What is the role of the tail for the sperm?
Definition
whip like movements propel the sperm
Term
Where does sperm develop?
Definition
between the two epithelial sertoli cells (from the basement membrane down to the lumen)

there is a tight junction between the two cells (blood testis barrier)
Term
Describe the start of spermatogenesis
Definition
at the basement membrane
in the seminiferous tubules from undifferentiated germ cells (spermatogenia)
Term
What happens to the spermatogenia
Definition
they migrate towards the lumen through the sertoli cells
mitosis (splits)
one goes back to the germ cell pool
the other undergoes another meiosis
then meiosis again
then becomes spermatoza
Term
What happens to the spermatoza
Definition
they remain immotile for 20 days in luminal fluid
they move down epididymas and persistalsis moves them down vas deferens when aroused
Term
What is male reproduction mainly under the control of?
Definition
GnRH, Testosterone, FSH, LH and (negative feedback) inhibins.
Term
What are the different types of oral contraceptive pills?
Definition
Combined pill (Oestrogens and progestins) or Mini pill (progestin only)
Term
What are the main effects of the oral contraceptive pill?
Definition
prevent ovulation (production of the egg)
Term
What are the secondary effects of the oral contraceptive pill?
Definition
discourage fertilisation eg:
implantation
Term
Name the synthetic oestrogens
Definition
Ethinylestradiol and mestranol (similar potency)
Term
Name the synthetic progestins
Definition
Northisterone, levonorgestrel – first generation
Desogestrel, gestodene- newer agents

Different potencies
Term
What causes the side effects of progestins?
Definition
Northisterone -> adrogenic (increase levels of oestrogens and stimulate male sexual characteristics)

Gestodene and desogestrel -> antiandrogenic (lower levels of oestrogen) and stimulate SHBG (produced when pregnant therefore stops pregnant)
Term
What is the most popular (and cheapest) type of combined oral contraceptive?
Definition
monophasic
identical 21 pills
contain oestrogen plus progesterone
Term
What are the more complex bi/triphasic combined pills like?
Definition
Designed to mimic cycle more closely Both oestrogen and progestin dose varied once or twice
Often need higher oestrogen dose to inhibit ovulation
Progestin overall intake reduced – less side effects
Term
What are the side effects of the combined pill?
Definition
Breakthrough bleeding
Weight gain
Effect sexuality
Depression
Term
Describe the mechanism of the combined pill?
Definition
Based on the fact that ovulation is suppressed in pregnancy
Progesterone increases (when pregnant)
S
Term
Which hormones are suppressed by negative feedback at hypothalamus and pituitary?
Definition
Suppressed secretion of FSH and LH
Low FSH suppressed by oestrogen
Low LH, Progestin effects LH surge
Term
What are the specific effects of the combined pill?
Definition
Cervical mucus thickens, viscous and scanty
Impairs motility of uterus and oviduct
Endometrial changes not conducive to implantation
Decreased production of glycogen- decreased energy for blastocyst to survive in uterus
Term
How does the mini pill differ?
Definition
progestin only
everyday (no 7 day break)
Term
Who is the mini pill recommended for?
Definition
Breast-feeding mothers
Women who cannot take oestrogens
Diabetics-though younger ones may take the combined pill
Older women
Heavy smokers
Anyone who wants to take a break from the combined pill
Term
What are the side effects of the mini pill?
Definition
irregular bleeding,
amenorrhoea,
ectopic pregnancy
unpredictable bleeding
mastalgia
weight gain but less than combined
small risk of breast cancer but less than combined
Term
What are the benefits of oral contraceptives?
Definition
Can reduce period pains
Periods shorter and lighter - because of this, you are less likely to become anaemic
Acne, the Pill should improve it
Delay menstruation
Can decrease chances of getting certain cancers (though it increases the risk of others)
Term
What are the risks of oral contraceptives?
Definition
DVT, clotting
Heart attacks, strokes
More common if smoke, overweight, diabetic, high blood pressure, high cholesterol
Term
What are the other hormone based contraceptions?
Definition
Injectable progestin (Depo Provera)
Subcutaneous implants (Norplant)
Hormone impregnated IUD (Mirena)
Term
Describe Injectable progestin (Depo Provera)
Definition
Intramuscular injection of medroxy-progesterone acetate (DMPA)
prevents surge LH
Term
Describe Subcutaneous implants (Norplant)
Definition
Progestin e.g. levonorgestral released from implanted silicone capsules/tubes
Term
Describe Hormone impregnated IUD (Mirena)
Definition
IUD – made from inert plastic (not copper coil)
Progestin impregnated
Prevent sperm reaching fallopian tube
Term
Describe post-sexual intercourse preparations
Definition
Morning after pills
Effective if first dose taken within 24-72 hours.
Taking first dose ASAP increases efficacy. Lessens the later you leave it.
Term
What does morning after pill do?
Definition
Delays ovulation
Interfere with transport and implantation
Interferes with endometrial development
Failure rate 10%
Nausea
Term
Describe the abortion pill
Definition
Anti progesterone (abortion pill)
For pregnancies up to 63 days (9 weeks)
Binds to progesterone receptors
Gestation up to 63 days
36-48 hours after taking mifepristone – insert prostaglandins in vagina and causes uterine contractions leading to miscarriage
Term
What is a natural contraception method?
Definition
1. not having sex between day 10 and day 17 of the cycle
2. monitor temp (Temp increase by 0.4 -0.8°F between 1 and 3 days after ovulation)
3. Assessment of cervical mucus – Billings method
4. Kits predicting ovulation
Term
What causes infertility?
Definition
35% female
24% male
28% unexplained
13% other
Term
what is inversely proportional to percent of max fertility for females?
Definition
miscarriage rate
Term
What factors cause female infertility?
Definition
ovulatory failure
impared gamete/zygote transport
implantation defects
developmental abnormalities of internal genitalia
Term
What is the favourable sperm count?
Definition
Count: approx. 40 million
Concentration: 20 million/ml
Term
Define oligozoospermia
Definition
low sperm count
Term
Define asthenozoospermia
Definition
Poor sperm motility
Term
Define teratozoospermia
Definition
Sperm morphology is wrong
Term
Define oligoasthenoteratozoospermia
Definition
Everything is wrong
Term
Define azoospermia
Definition
No sperm
Term
What can be done to help a female ovulate?
Definition
The use of medication to stimulate the ovaries into producing oocytes
Clomiphene citrate: orally active increased FSH and LH
Injectable gonadotrophins
GnRH pump
Bromocriptine
Term
Describe clomiphene citrate
Definition
“Selective Estrogen Receptor Modulators” (SERMs)
A non-steroidal compound with close structural similarity to oestradiol
Term
What does clomiphene citrate act as?
Definition
Clomiphene is a partial agonist in the ovaries and oestrogen receptor antagonist in the hypothalamus.
Term
Describe the mechanism of action of clomiphene citrate
Definition
inhibits the negative feedback of oestrogen
in turn promotes gonadotrophin release
promotes release of FSH and LH
stimulates ovulation
Term
How effective is clomiphene?
Definition
ovulation is induced in about 70% of cases
pregnancy occurs in only 10-15% of cases
Term
Why does clomiphene citrate have low pregnancy rates?
Definition
1.anti-oestrogenic effects on cervix
- makes hostile to sperm penetration
- affects embryo implantation
2.can cause premature luteinisation
3.decrease in quality of ova produced
Term
What injectable Gonadotrophins are there?
Definition
Follitropin
FSH
Started early in cycle 8-14 days
Induces production of follicles
Term
What injectable menotrophin are there?
Definition
Menotrophin
HCG
Induces ovulation approx 36 hours later
Risk of overstimulation
90% anovulatory women ovulate
Pregnancy rate 15%
Term
What methods of assisted contraception are there?
Definition
Intrauterine insemination (IUI)
Artificial insemination (AI)
IVF-ET: in vitro fertilisation and embryo transfer
Term
Describe IVF-ET
Definition
Fertilisation occurs outside the body
Embryo transferred afterwards
Most useful where the women has absent or blocked fallopian tubes
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