Endocrine Glands

pituitary (hypophysis)

thyroid

parathyroid

adrenal

pineal

thymus

Hormones

chemical substances created by cells into the extracellular fluids

regulate metabolic function of other cells

have lag times ranging from seconds to hours

tend to have prolonged effects

Eicosanoids

biologically active lipids with local hormone

Humoral Stimuli

secretion of hormones in direct response to changing blood levels of ions and nutrients

declining blood Ca2+ concentration stimulate the parathyroid glands to secret PTH

PTH causes Ca2+ concentrations to rise and the stimulus is removed

Neural Stimuli

nerve fibers stimulate hormone release

preganglionic sympathetic nervous system fibers stimulate the adrenal medulla to secrete catecholamines

Hormonal Stimuli

release of hormones in response to hormones produced by other endocrine organs

the hypothalamic hormones stiumlate the anterior pituitary

pituitary hormones then stimulate targets to secrete still more hormones

Pituitary Gland

two-lobed organ that secretes nine major hormones`

Neurohypophysis

posterior lobe (neural tissue) and the infundibulum

Adenohypophysis

anterior lobe, made up of glandular tissue

hormones - GH, TSH, ACTH, FSH, LH, PRL

regulate activity of other endocrine glands

Thyroid Gland

largest endocrine gland lovated in anterior neck

consists of tow lateral lobes connected by a median tissue mass called isthmus

composed of follicles that produce the glycoprotein thyroglobulin

Thyroid Hormones

T4 - thyroxine; has two tyrosine molecules plus four bound iodine atoms

T3 - tiiodothyronine; has two tyrosines with three bound iodine atoms

Parathyroid Glands

tiny glands embedded in posterior aspect of thyroid

cells are arranged in cords containing oxyphil and cheif cells

cheif (principal) cells secrete PTH

PTH regulates calcium balance in the blood

Adrenal (Suprarenal) Glands

paired, pyramid shaped organs atop the kidneys

structurally/functionally two glands in one

adrenal medulla

adrenal cortex

Adrenal medulla

neural tissue that acts as part of the SNS

made up of chromadffin cells that secrete epinephrine/norepinephrine

causes blood glucose levels to rise

blood vessels to constrict

heart to beat faster

blood to be diverted to brain, heart, skeletal muscle

Adrenal Cortex

glandular tissue derived from embryonic mesoderm

synthesizes and releases steroid hormones called corticosteroids

different corticosteroids are produced in each of the three layers

zona glomerulosa

zona fasciculata

zona reticularis

Pancreas

both exocrine/endocrine cells

located behind stomach

acinar cells produce digestive enzymes

pancreatic islets (islets of Langerhans) produce hormones

islets contain:

alpha cells - glucagon

beta cells - produce insulin

delta cells - secrete somatatosin

Zona Glomerulosa

mineralocorticoids

chiefly aldosterone

Zona Fasciculata

glucocorticoids

chiefly cortisol

Zona Reticularis

gonadocorticoids

cheifly androgens

(sex hormones)

Diabetes Mellitus

pancreas does not secrete enough insulin

cells cannot absorb glucose

low energy levels

polyuria

polydypsia

polyphagia

Diabetes Insipidus

posterior pituitary does not make enough ADH or its effects are blocked

ADH helps absorb water in the kidneys

low ADH causes large volumes of urine

Hyperthyroidism (Graves Disease)

hypersecretion of thyroxine by thyroid gland

thyroid may be malfunctioning too much TSH from pituitary

increased metabolic rate, increased HR, weight loss, sweating, high BP, protruding eyeballs

Hypothyroidism (Goiter)

iodine deficiency causes less thyroxine to be released by thyroid gland

causes low metabolic rate, weight gain, cold, slow pulse, puffy, low thyroxine

breaks negative feedback loop thus pituitary keeps releasing TSH

causes thyroid to swell

Hypothyroidism (Cretenism)

in babies

normal thyroxine levels at birth via mother

low thyroxine after birth

abnormal bone development, mental retardation, low body temp, lethargy, stunted growth

Hypothyroidism (Myxedema)

in adults

low thyroxine

low metabolic rate

lethargy, weight gain, edema, hair loss

Dwarfism

the anterior pituitary does not release enough growth hormones

reduced muscle and bone growth

stunted

Gigantism

anterior pituitary releases too much growth hormone

bones and muscles grow to abnormally large sizes

SADS

(season affective disorder)

pineal gland behind eye releases too much melatonin

cells prepare for winter

sleepy, sad, tired, weight gain, depressed

Acromegaly

anterior pituitary releases too much growth hormone after the growth plates have fused together

bones can no longer grow in length but instead widen and thicken