Term
| what is the difference between the anterior and posterior sections of the pituitary? |
|
Definition
Posterior pituitary
(neurohypophysis) ‐Made up
of nervous tissue
– Anterior pituitary
(adenohypophysis) ‐
Composed of glandular
epithelial tissue |
|
|
Term
| how is the pituitary regulated? |
|
Definition
|
|
Term
| what are the two categories of hormones? |
|
Definition
hydrophilic or lipophilic.
examples of hydrophilics are: peptide hormones, catecholamines
examples of lipophilics are: steroid hormones and thyroid hormones. |
|
|
Term
| what are some examples of systems in your body that are under endocrine regulations? |
|
Definition
Regulate metabolism, H2O and
electrolyte balance
– Adaptation to stressful situations
– Promote growth and development
– Reproductive control
– Regulation of red blood cell
production
– Works in conjunction with
autonomic nervous system
• Circulation
• Food digestion and absorption |
|
|
Term
| how do we maintain an effective plasma hormone concentration? |
|
Definition
| we regulate the rate of secretion. it is also heavily influenced by its transport, metabolism, and excretion |
|
|
Term
| what are tropic hormones, and what are some examples? |
|
Definition
Regulates hormone secretion
by another endocrine gland
• Stimulates and maintains
integrity of target endocrine
tissues
• Examples:
–Thyroid‐stimulating
hormone (TSH) from
anterior pituitary
stimulates thyroid
hormone secretion
–TSH also necessary for
structural integrity of
thyroid gland |
|
|
Term
| what inputs influence the outputs of endocrine cells? |
|
Definition
Two types of inputs influence
output of endocrine cells
–Neural
–Hormonal
• Other influences on effective
plasma concentration:
–Rate of removal/excretion
–Rate of activation/extent of
binding to plasma proteins |
|
|
Term
| plasma concentration of free biologically active hormone depends on what 4 factors? |
|
Definition
1. Hormone’s rate of secretion by
endocrine gland (most important)
2. Rate of metabolic activation (few
hormones)
3. Extent of binding to plasma
proteins (lipophilic)
4. Rate of metabolic inactivation and
excretion (all) |
|
|
Term
| what happens when a lipophilic hormone encounters its target cell? |
|
Definition
Lipophilic hormone diffuses
through nuclear membranes of
target cells and binds to
nuclear receptor specific for it
2. Hormone receptor complex in
turn binds with hormone
response element, a DNA
segment specific for hormone
receptor complex
3. DNA binding activates specific
genes, producing
complementary messenger
RNA
4. mRNA leaves nucleus and
directs new protein synthesis.
5. New proteins accomplish
target cell’s ultimate
physiologic response to the
hormone |
|
|
Term
| what are some examples of hydrophilic hormones? how does their function differ from lipophilic hormones? |
|
Definition
hydrophilic hormones bind to receptors on the cell surface to activate some second messanger system and then you MODIFY an existing protein (phosphorylation and dephosphorylation)
examples are: ACTH, CRH, Calcitonin, FSH, Glucagon,
LH, Melanocyte Stimulating
Hormone, Parathyroid Hormone, Thyroid
Stimulating Hormone |
|
|
Term
| what are the two major regulatory factors of the pituitary? |
|
Definition
Hypothalamic hormones
– Feedback from target gland
hormones |
|
|
Term
| the hypothalamus + the posterior pituitary = the neuroendocrine system. what two small peptide hormones are stored and released in this system? |
|
Definition
Vasopressin(aka,
antidiuretic hormone, ADH):
conserves H2O during urine
formation by nephrons
• Oxytocin: stimulates uterine
contraction during birthing
and milk ejection during
breast feeding. |
|
|
Term
| what are the nuclei in the hypothalamus that produce the hormones? |
|
Definition
| paraventricular and supraoptic nuclei. |
|
|
Term
| the anterior pituitary releases 6 hormones. what are they, and what are their functions? |
|
Definition
Thyroid‐stimulating hormone (TSH) ‐stimulates secretion of thyroid hormone
– Adrenocorticotropic hormone (ACTH) ‐stimulates secretion of cortisol by
adrenal cortex
– Follicle‐stimulating hormone (FSH)
• In females, stimulates growth and development of ovarian follicles;
promotes secretion of estrogen by ovaries
• In males, required for sperm production
– Luteinizing hormone (LH)
• In females, responsible for ovulation and luteinization (formation of
postovulatory corpus luteum); regulates ovarian secretion of female
estrogen and progesterone
• In males, stimulates testosterone secretion
– Growth hormone (GH) ‐primary hormone responsible for regulating overall
body growth; extremely important metabolic actions
– Prolactin (PRL) –only non‐tropic; breast development and milk production in females |
|
|
Term
|
Definition
|
|
Term
| their is a neural link between the hypothalamus and the posterior pituitary. how are the hypothalamus and the ANTERIOR pituitary linked? |
|
Definition
they are linked vascularly. Hypophysiotropic hormones produced
by hypothalamic neurons enter
hypothalamic capillaries
2. Hypothalamic capillaries rejoin to form
hypothalamic‐hypophyseal portal
system. This vascular link passes to the
anterior pituitary.
3. Here it branches into anterior pituitary
capillaries
4. Hypophysiotropic hormones leave
blood across anterior pituitary
capillaries and control the release of
anterior pituitary hormones
5. On stimulation by appropriate
hypothalamic releasing hormone, a
given anterior pituitary hormone is
secreted into these capillaries
6. The anterior pituitary capillaries rejoin
to form a vein, through which the
anterior pituitary hormones leave for
distribution throughout body by
systemic circulation |
|
|
Term
| what hormones are important for pubertal growth in boys and girls, respectively? |
|
Definition
Testosterone extremely
important in adolescent boys
– Adrenal androgens from
adrenal gland are important in
female pubertal growth spurt
(DHEA) |
|
|
Term
| what is the primary effect of growth hormone? |
|
Definition
Promotes growth by stimulating liver’s production of
somatomedins (aka, insulin‐like growth factors)
• Primary somatomedin is insulin‐like growth factor 1 (IGF‐1)
–Acts directly on bone and soft tissues
–Stimulates protein synthesis, cell division, and
lengthening/thickening of bones
• Promotes metabolic effects not related to growth
–Increases fatty acid levels in blood by breakdown of
triglyceride fat in adipose tissue
–Increases blood glucose levels by decreasing glucose
uptake by muscles |
|
|
Term
| what are some growth hormone abnormalities? |
|
Definition
GH deficiency
– May be due to either pituitary defect or
hypothalamic dysfunction
– Hyposecretion of GH in child = dwarfism
– Hyposecretion in adult = relatively few
symptoms
• GH excess
– Most often due to tumor of GH‐producing
cells of anterior pituitary
– Symptoms depend on age:
• Hypersecretion in child before
epiphyseal plates close = gigantism
• Hypersecretion after adolescence =
acromegaly (acro = “extremity”;
megaly = “large” |
|
|
Term
| what are some important hormones for normal growth? |
|
Definition
Thyroid hormone (TH)
– Severely stunted growth in children with hypothyroidism
– Hyperthyroid does not cause excessive growth
• Insulin
– Deficiency blocks growth
– Hyperinsulinism can spur excessive growth
• Androgens (eg, testosterone, dehydroepiandosterone)
– Important for pubertal growth spurt; stimulates protein synthesis in
many organs
– Effects depend on presence of GH
• Estrogens –effects on growth prior to maturation not well
understood |
|
|
Term
| what is the suprachiasmatic nucleus? |
|
Definition
Cluster of neurons in hypothalamus:
Master biological clock
– Works with pineal gland to synchronize
circadian rhythms
– Set daily by external cues (“clock”
synchronized with environment)
– Self‐induced cyclic variations in clock
protein concentrations in SCN ‐ alter
SCN discharge
• Genes promote synthesis of clock
proteins; when levels high, inhibit
their own production
• Day long cycle
• Drives body’s circadian rhythms |
|
|
Term
| what is the pineal gland, and what does it do? |
|
Definition
Tiny, pinecone‐shaped gland located in
center of brain
• Secretes melatonin
– Hormone of darkness‐Secretion
falls to low levels during daylight
hours
– Helps keep body’s circadian rhythms
in synch with light‐dark cycle
– Promotes sleep
– Influences reproductive activity,
including onset of puberty
– Immune functions |
|
|
Term
| what are the peripheral endocrine glands? |
|
Definition
Thyroid
• Adrenal –cortex and medulla
• Endocrine pancreas
• Parathyroid
• Testes and Ovaries (discussed later) |
|
|
Term
| what are the main effects of the thyroid gland? |
|
Definition
Effects of thyroid hormone:
– Main determinant of basal metabolic rate
• Influences synthesis and degradation of
carbohydrates, fats, and proteins
• Increases target cell responsiveness to
catecholamines
– Increases heart rate and force of contraction
– Essential for normal growth, CNS/PNS
development (stimulates GH and IGF‐1) |
|
|
Term
| what are the two main cells of the thyroid gland, and how do they work? |
|
Definition
Follicular cells
–Arranged into hollow spheres
–Forms functional unit = follicle
–Lumen filled with colloid
• Extracellular storage site for
thyroid hormone
–Produce 2 iodine‐containing
hormones derived from tyrosine
• Tetraiodothyronine (T
4
or
thyroxine)
• Tri‐iodothyronine (T
3
)
• C cells ‐ secrete peptide hormone
calcitonin |
|
|
Term
| how does the synthesis of thyroid hormone work? |
|
Definition
Basic ingredients:
– Tyrosine: synthesized in sufficient amounts by body
– Iodine: obtained from dietary intake
• Synthesis: all steps occur within colloid on thyroglobulin
molecules (large glycoproteins in which TH is incorporated)
– Tyrosine‐containing thyroglobulin is exported from follicular cells into
colloid by exocytosis
– Thyroid captures iodine from blood and transfers it into colloid by
iodine pump
– When in colloid, iodine attaches to tyrosine
– Coupling process between iodinated tyrosine molecules occurs to
form thyroid hormones |
|
|
Term
| how is thyroid hormone stored and secreted? |
|
Definition
Storage:
–Thyroid hormones remain in colloid until they are split off
and secreted
–Enough is typically stored to last body several months
• Secretion:
–Follicular cells phagocytize thyroglobulin‐laden colloid
–Process frees T
3 and T4 to diffuse across plasma membrane
and into blood |
|
|
Term
|
Definition
1. Tyrosine‐containing Tg produced within thyroid follicular cells is transported into colloid
by exocytosis
2. Iodine actively transported from blood into colloid by follicular cells
3. Attachment of one iodide to tyrosine within Tg molecule yields MIT (monoiodotyrosine),
attachment of two yields DIT (di‐iodotyrosine)
4. Coupling of one MIT and one DIT yields T
3;
coupling of two DITs yields T
4.
5. On appropriate stimulation, thyroid follicular cells engulf portion of Tg‐containing colloid
by phagocytosis
6. Lysosomes attack engulfed vesicle and split the iodinated products from Tg
7. T3 and T
4diffuse into blood (quickly attach to plasma protein –mostly thyroxine‐binding
globulin)
8. MIT and DIT are deiodinated, and freed iodine is recycled for synthesizing more hormone
90% of secretory product is T4,
but T3
is 10 x’s more
potent. Most T
4
gets converted to T
3outside thyroid
gland, predominantly by liver and kidneys |
|
|
Term
| what are the effects of thyroid hormone? |
|
Definition
Main determinant of basal metabolic rate (affects nearly
every tissue in the body): most important regulator of
body’s rate of O2consumption and energy use at rest
–Influences synthesis and degradation of carbohydrates,
fats, and proteins (depends on amount circulating)
–Increases target cell responsiveness to catecholamines
–Increases heart rate and force of contraction
–Essential for normal growth
–Plays crucial role in normal nervous system development
(stimulates GH secretion and IGF‐1 production) |
|
|
Term
| what affects thyroid hormone levels in the body? |
|
Definition
Hypothalamic‐Pituitary‐Thyroid Axis
stress and cold in infants.
Regulated by negative feedback
system between hypothalamic
TRH, anterior pituitary TSH, and
thyroid gland T
3and T
4
– Feedback loop keeps relatively
constant level of thyroid hormones
Stimulation of TH production by cold
temperatures is highly adaptive – need
more endogenous heat production
after going from womb to outside
world. Possibly a factor in long term
adaptation to colder climates in
children and adults |
|
|
Term
| what are some hypothyroid abnormalities? |
|
Definition
Causes
• Primary failure of thyroid gland
• Secondary to a deficiency of TRH, TSH, or both
• Iodine deficiency in diet
– Cretinism
• Results from hypothyroidism from birth
• Characterized by dwarfism and mental
retardation
• Mental retardation is irreversible if not treated
within months after birth
– Myxedema
• Hypothyroidism in adults (later onset)
• Edematous condition caused by infiltration of
skin with complex, water‐retaining
carbohydrate molecules
– Treatment
• Replacement therapy
• Dietary iodine
Goiter |
|
|
Term
| what are the possible causes of hypothyroidism |
|
Definition
1.failure of thyroid gland results in decrease in T3 and T4, but INCREASE in TSH from hypothal - Goiter
2. secondary to hypothalamic or anterior pituitary failure, you will see decrease T3 and T4, decrease in TRH and TSH, so no goiter
3.lack of dietary iodine results in decreased t3 and t4, plus increase in tsh, so we get a goiter |
|
|
Term
| what is graves disease and how is it treated? |
|
Definition
–Autoimmune disease
–Body overproduces thyroid‐
stimulating immunoglobulins
(TSI)
–Characterized by exophthalmos
• Treatment
–Surgical removal of part of gland
–Administration of radioactive
iodine: oversecreting cells are
destroyed, then patient goes on
hormone replacement therapy
–Antithyroid drugs |
|
|
Term
| what are the 3 layers of the adrenal glands? |
|
Definition
3 layers of adrenal cortex
– Zona glomerulosa – (aldosterone here)outermost layer
– Zona fasciculata – middle portion (largest)
– Zona reticularis – innermost layer |
|
|
Term
| What are the 2 endocrine glands that comprise the adrenal glands? |
|
Definition
Adrenal cortex
• Outer portion
• Secretes steroid
hormones
–Adrenal medulla
• Inner portion
• Secretes
catecholamines |
|
|
Term
| what are the 3 types of adrenal steroids? |
|
Definition
Mineralocorticoids (glomerulosa)
• Aldosterone – influences mineral balance,
Na+
and K
+
– Glucocorticoids (fasc. and reticularis)
• Cortisol – major role in glucose
metabolism; also protein and lipid
metabolism
– Sex hormones (fasc. and reticularis)
• Identical to ones produced by gonads
• Most abundant and physiologically
important is dehydroepiandosterone (male
“sex” hormone) |
|
|
Term
| how does aldosterone function? |
|
Definition
Principal site of action is on distal and collecting tubules of the
kidney
• Secretion is increased by:
–Activation of renin‐angiotensin‐aldosterone system due to
reduction in Na+
and/or fall in blood pressure
–Direct stimulation of adrenal cortex by rise in plasma K
+
concentration
• Regulation of aldosterone secretion is largely independent of
anterior pituitary control |
|
|
Term
| what are some causes and symptoms of aldosterone hypersecretion? |
|
Definition
–Causes:
• Hypersecreting adrenal tumor made up of aldosterone‐
secreting cells
–Primary hyperaldosteronism or Conn’s syndrome
• Inappropriately high activity of the renin‐angiotensin
system – secondary hyperaldosteronism
–Symptoms:
• Excessive Na+
retention and K+ depletion
• High blood pressure |
|
|
Term
| what are the functions of cortisol? |
|
Definition
Cortisol
– Stimulates hepatic
gluconeogenesis
– Stimulates protein
degradation
– Facilitates lipolysis
– Secretion is regulated by
negative‐feedback loop
involving hypothalamic CRH
and pituitary ACTH
Metabolic fuels
and building blocks
available to help
resist stress (i.e., help with
repair of damaged tissue or
synthesis of new cellular
structure |
|
|
Term
| at pharmacological levels, what does cortisol do? |
|
Definition
can have
anti‐inflammatory and
immunosuppressive effects (many bad
side effects with long‐term use
Blocks production of
prostaglandins and leukotrienes
– Suppresses migration of
neutrophils
– Inhibits proliferation of fibroblasts
in wound repair |
|
|
Term
| what are the causes, signs, and symptoms of cortisol hypersecretion? |
|
Definition
Aka, Cushing’s syndrome
• Causes
– Overstimulation of adrenal cortex
by excessive amounts of CRH and
ACTH
– Adrenal tumors that
uncontrollably secrete cortisol
independent of ACTH
– ACTH‐secreting tumors located in
places other than pituitary
• Signs and symptoms:
– Hyperglycemia and glucosuria
(adrenal diabetes)
– Abnormal fat distribution –
“buffalo hump” and “moon face”
– Weakness, fatigue
– Overstretched abdominal skin
– Poor wound healing |
|
|
Term
| what is dehydroepiandosterone |
|
Definition
Dehydroepiandosterone (DHEA)
• Only adrenal sex hormone that has any biological
importance
• Overpowered by testicular testosterone in males
• Physiologically significant in females:
–Enhancement of pubertal growth spurt
–Development and maintenance of female sex drive
–Growth of pubic and axillary hair |
|
|
Term
| what are some symptoms of adrenal androgen hypersecretion in females and males? |
|
Definition
Symptoms:
– Adult females
• Hirsutism
• Deepening of voice, larger
muscles
• Smaller breasts, amenorrhea
– Newborn females ‐Have male‐
type external genitalia
– Prepubertal males ‐Precocious
pseudopuberty (testes are still in
non‐functional state)
– No apparent effect on adult
males |
|
|
Term
| know the pathway for adrenogenital syndrome. |
|
Definition
|
|
Term
| what is addisons disease? |
|
Definition
Primary Adrenocortical Insufficiency.
Autoimmune disorder –erroneous production of
adrenal cortex‐attacking antibodies
–Aldosterone deficiency
• Hyperkalemia and hyponatremia lead to
cardiac arrhythmia and low BP
–Cortisol deficiency
• Poor response to stress
• Hypoglycemia
• Lack of permissive action for many metabolic
activities
• Secondary adrenocortical insufficiency
–Occurs because of pituitary or hypothalamic
abnormality
–Only cortisol is deficient |
|
|
Term
| what is the adrenal medulla, and what are its functions? |
|
Definition
Modified part of sympathetic nervous system
• Activation of sympathetic nervous system by stress is primary
stimulus for increased adrenomedullary secretion
• Releases epinephrine and norepinephrine
–Secreted into blood by exocytosis of chromaffin granules
–Vary in their affinities for the different adrenergic receptor types
• Epinephrine:
–Reinforces sympathetic system in mounting general systemic
“fight‐or‐flight” responses
–Maintenance of arterial blood pressure
–Increases blood glucose and blood fatty acids
–Release facilitates exercise performance; however, chronic
release in face of psychosocial stressors has harmful effects |
|
|
Term
| what is the stress response? |
|
Definition
Pattern of reactions to a
situation that threatens
homeostasis
• Stress: generalized nonspecific
response of body to any factor
that overwhelms or threatens
to overwhelm the body’s
ability to maintain homeostasis
• Stressor: any noxious stimulus
that brings about the stress
response |
|
|
Term
| what are the endocrine parts of the stress response? |
|
Definition
Generalized stress response:
–Activation of sympathetic nervous system
accompanied by epinephrine secretion
• Prepares body for fight‐or‐flight response
–Activation of CRH‐ACTH‐cortisol system
• Helps body cope by mobilizing metabolic resources
–Elevation of blood glucose and fatty acids
• Less insulin, more glucagon secretion
–Maintenance of blood volume and blood pressure
• Increased renin‐angiotensin‐aldosterone activity and more
vasopressin secretion |
|
|
Term
| define anabolism and catabolism. |
|
Definition
Anabolism
–Synthesis of larger organic macromolecules from small organic
subunits
–Reactions usually require ATP energy
–Reactions needed for energy result in:
• Manufacture of materials needed by cell
• Storage of excess ingested nutrients not immediately needed for
energy production or needed as cellular building blocks
• Catabolism
–Breakdown or degradation of large, energy‐rich organic
molecules within cells
–2 levels of breakdown:
• Hydrolysis of large cellular molecules into smaller subunits
• Oxidation of smaller subunits to yield energy for ATP production |
|
|
Term
| what are the pancreatic cells, and what are their functions? |
|
Definition
Endocrine cells –Islets of Langerhans
– βcells ‐insulin synthesis,
secretion
– αcells ‐Produce glucagon
– δcells ‐somatostatin
– F cells
• Least common islet cells
• Secrete pancreatic
polypeptide
• |
|
|
Term
| what does somatostatin do? |
|
Definition
Released from pancreatic δ cells in response to
increase in blood sugar and blood amino acids
during absorption of a meal
–Puts brakes on rate at which meal is digested and
absorbed ‐ prevents excessive plasma levels of
nutrients
–Local presence of somatostatin decreases
secretion of insulin, glucagon, and somatostatin
itself (paracrine) = negative feedback |
|
|
Term
| how is insulin secreted by the beta cells in the pancrease? |
|
Definition
1. Glucose enters βcell by facilitated diffusion via GLUT‐2
2. Glucose phosphorylated to glucose‐6‐phosphate
3. Oxidation of glucose‐6‐phosphate generates ATP
4. ATP acts on ATP‐sensitive K
+
channel, closing it
5. Reduced exit of K
+
depolarizes membrane
6. Depolarization opens voltage‐gated Ca
2+
channels
7. Ca
2+
enters βcell
8. Ca
2+
triggers exocytosis of insulin vesicles
9. Insulin secreted |
|
|
Term
| insulins normal receptor is of what type? |
|
Definition
|
|
Term
| normally insulin is the only way to get glut 4 receptors to the surface. But what happens when you exercise? |
|
Definition
| muscle contraction can trigger GLUT4 receptor insertion into the membrane, independent of insulin. |
|
|
Term
| what is the function of glucagon? |
|
Definition
Mobilizes energy‐rich molecules from storage sites
during postabsorptive state
–Secreted in response to fall in blood glucose
sensed by pancreatic α cells
–Opposes actions of insulin
–No known clinical abnormalities caused by
glucagon deficiency or excess, but excess of glucose can aggravate hyperglycemia of diabetes mellitus |
|
|
Term
| if you had a glucagon deficiency, what other hormones may compensate? |
|
Definition
| coritsol, growth hormone, and thyroid hormone may help compensate |
|
|
Term
| why is plasma calcium so closely regulated by the body? |
|
Definition
to prevent changes in neuromuscular excitability
–Also plays vital role in a number of essential activities
• Excitation‐contraction coupling in cardiac and smooth muscle
• Stimulus‐secretion coupling
• Maintenance of tight junctions between cells
• Blood clotting
–Hypercalcemia reduces excitability
–Hypocalcemia causes overexcitability of nerves and muscles
• Can cause fatal spastic contractions of respiratory muscles
• Increases Na+ permeability moving resting potential closer to threshold |
|
|
Term
| what 3 hormones regulate plasma Ca+2 concentration? |
|
Definition
–Parathyroid hormone (PTH)
–Calcitonin (made in thyroid T cells)
–Vitamin D |
|
|
Term
| what is the function of parathyroid hormone, and how does it work? |
|
Definition
Secreted by parathyroid glands
–Primary regulator of Ca
2+
: raises free plasma Ca
2+
levels by its effects on bone, kidneys, and
intestines
–Essential for life: prevents fatal consequences of
hypocalcemia
–Facilitates activation of Vitamin D
–Stimulates osteoblastic upregulation of RANK
ligand: RANKL binds to RANK on osteoclast
precursors and promotes osteoclast
differentiation and survival |
|
|
Term
| What is the RANK ligand. how does it function to increase or decrease calcium levels? |
|
Definition
|
|
Term
| what is vitamin D's function, and what is its cascade of action? |
|
Definition
Stimulates Ca
2+
and PO4
3‐
absorption from
intestine
–Can be synthesized from cholesterol derivative
when exposed to sunlight (usually inadequate
source)
–Amount supplemented by dietary intake
–Must be activated first by liver and then by
kidneys before it can exert its effect on intestines
–Increases responsiveness of bone to PTH
active vitamin D3, either through diet or sunlight, gets....ADD THIS TO SLIDE (SLIDE 31) |
|
|
Term
| what is calcitonin, and how does it work? |
|
Definition
Hormone produced by C cells of thyroid gland
–Acts to lower plasma Ca
2+
levels by inhibiting
activity of bone osteoclasts
–Negative‐feedback: secreted in response to
increases in plasma Ca
2+ concentration
–Important during hypercalcemia |
|
|
Term
| how doe negative feedback loops control parathyroid hormone and calcitonin secretion (these hormones have opposing actions) |
|
Definition
|
|
Term
| what are some calcium disorders, and what are their symptoms? |
|
Definition
PTH hypersecretion (hyperparathyroidism)
• Characterized by hypercalcemia and hypophosphatemia
• Reduced excitability of muscle and nervous tissue
• Cognitive deficits
• Cardiac problems
PTH hyposecretion (hypoparathyroidism)
• Characterized by hypocalcemia and
hyperphosphatemia
• Increased excitability of muscle and nerve
• Fatal if no production of PTH
Vitamin D deficiency
• PTH maintains plasma Ca
2+
at expense of bones
• Children –rickets; Adults ‐osteomalacia |
|
|
Term
| what cells in the testes secret testosterone? |
|
Definition
|
|
Term
| what two hormones are essential for testosterone regulation? |
|
Definition
| follicle stimulating hormone, and leutinizing hormone. |
|
|
Term
| what are some of the functions of testosterone? |
|
Definition
Steroid hormone derived from
cholesterol precursor molecule
• Masculinizes reproductive tract and
external genitalia
• Promotes growth and maturation
of reproductive system at puberty
• Essential for spermatogenesis
• Develops sex drive at puberty
• Controls gonadotropin hormone
secretion
• Promotes muscle growth
• Exerts protein anabolic effect
• Promotes bone growth at puberty
and then closure of epiphyseal
plates
• May induce aggressive behavior |
|
|
Term
| what are the actions of estrogen and progesterone? |
|
Definition
Estrogen
–Essential for ova
maturation and release
–Establishment of female
secondary sexual
characteristics
–Essential for transport of
sperm from vagina to
fertilization site in
oviduct
–Contributes to breast
development in
anticipation of lactation
• Progesterone
–Important in preparing
environment for
developing
embryo/fetus
–Milk production |
|
|
Term
| What are the main points of the ovarian cycle, and what are its two phases? |
|
Definition
Average ovarian cycle lasts 28 days
• Normally interrupted only by pregnancy
• Finally terminated by menopause
• Consists of two alternating phases
–Follicular phase: dominated by presence of maturing
follicles
–Luteal phase: characterized by presence of corpus luteum |
|
|
Term
| describe the follicular phase of the ovarian cycle. |
|
Definition
Follicular phase
– Operates first half of cycle
– Granulosa cells of some primary
follicles proliferate
– Oocyte inside each follicle enlarges
– Thecal cells in follicle secrete
increased amounts of estrogen
– Rapid follicular growth continues
during follicular phase
– One follicle usually grows more
rapidly and matures about 14 days
after onset of follicular development
• Follicle ruptures to release
oocyte from ovary
• Event is called ovulation
• Released oocyte enters oviduct
where it may or may not be
fertilized |
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Term
| describe the luteal phase of the ovarian cycle. |
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Definition
Last 14 days of ovarian cycle
• Old follicular cells transform into corpus
luteum: function is to secrete lots of
progesterone, some estrogen
• Becomes highly vascularized
• Becomes fully functional within four days
after ovulation
• Continues to increase in size for another
four or five days
• If released ovum is not fertilized and does
not implant, corpus luteum degenerates
within about 14 days after its formation
• If fertilization occurs, corpus luteum
continues growing and producing more
progesterone and estrogen instead of
degenerating: provides hormones
essential for maintaining pregnancy until developing placenta can take over |
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|
Term
| please describe the cycling of hormones in the female ovarian cycle. |
|
Definition
Hormonal interactions
– During follicular phase, rise in FSH
signals ovarian follicle to secrete more
estrogen
– Rise in estrogen feeds back to inhibit
FSH secretion which declines as
follicular phase proceeds
– LH rises in follicular phase
• As it peaks in mid‐cycle, it triggers
ovulation
– Estrogen output decreases and mature
follicle is converted to a corpus luteum
– Corpus luteum secretes progesterone
and estrogen during luteal phase
– Progesterone output inhibits release of
FSH and LH
• Low LH – corpus luteum
degenerates
• Progesterone levels decline
– FSH can start to rise again, initiatingnew cycle |
|
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Term
| what is the uterine cycle? |
|
Definition
Menstrual cycle –1st
day of menstruation is considered start
of new cycle
• Coincides with end of luteal phase and onset of new follicular
phase
• Reflects hormonal changes during ovarian cycle
• Averages 28 days
• Outward manifestation of cyclic changes in uterus is
menstrual bleeding once during each cycle |
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Term
|
Definition
Cessation of woman’s menstrual cycle
• Usually occurs between ages of 45 and 55
• Midlife hypothalamic change may trigger onset of menopause
• Preceded by period of progressive ovarian failure
–Increasingly irregular cycles
–Dwindling estrogen levels: primarily affects skeleton and
cardiovascular system
• Period of transition called the climacteric |
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