18.9 Secondary endocrine organs Flashcards
kidneys release..
calcitrol, erythropoietin, and renin
calcitrol
stimulation, effects
steroid hormone secreted in response to PTH
- stimulates calcium and phosphate ion absorption along digestive tract
- stimulates formation of osteoprogenitor cells and osteoclasts
- stimulates Ca2+ reabsorption by kidneys
- suppresses PTH production
EPO
stimulation, effects
erythropoietin
- released in response to low oxygen levels in kidney
- stimulates bone marrow to produce RBCs
Renin
stimulation, effects
enzyme released in response to sympathetic stimulation or a decline in renal blood flow
-starts cascade: renin-angiotensin system (renin converts angiotensinogen to angiotensin I, which is modified to angiotensin II)
angiotensin II
effects
stimulates secretion of aldosterone by adrenal cortex, and of ADH at posterior pituitary
- this restricts salt and water loss at kidneys
- stimulates thirst, elevates blood pressure
natriuretic peptides (ANP & BNP) stimulation, effects
- stimulated by large blood volume
- effects oppose angiotensin II (promote salt and water loss at kidneys
- inhibit secretion of renin, ADH and aldosterone, suppress thirst
- reduction in blood volume and blood pressure
thymus
thymosin: promotes development of lymphocytes (WBCs responsible for immunity)
interstitial cells of the testes
produce androgens
nurse cells in the testes
support differentiation and maturation of sperm
inhibin
secreted in response to FSH
-inhibits secretion of FSH & possible GnRH
estrogens
produced in ovaries under FSH and LH stimulation
principle progestin
progesterone
GH malfunctions
underproduction: pituitary growth failure
overproduction: gigantism, acromegaly
ADH/VP malfunctions
underproduction: diabetes insipidus
overproduction: SIADH (syndrome of inappropriate ADH secretion) - inc body weight & water content
T4, T3 malfunctions
underproduction: myxedemia, cretinism (low metabolic rate, low body temp, impaired phys and mental development)
overproduction: hyperthyroidism, graves disease (high metabolic rate and body temp)
PTH malfunctions
underproduction: hypoparathyroidism (muscle weakness, neurological problems, dense bones, tetany)
overproduction: hyperparathyroidism (neuro, mental, muscular problems due to high Ca2+, weak & brittle bones
insulin malfunctions
underproduction: diabetes mellitus (type 1)
overproduction: excess insulin (low glucose, possibly causing coma)
mineralcorticoids (MCs) malfunctions
underproduction: hypoaldosteronism (polyuria, low blood volume, high K+, low Na+
overproduction: aldosteronism (inc body weight due to high Na+ water retention, low K+)
glucocorticoids (GCs) malfunctions
underproduction: Addison’s disease (inability to tolerate stress, mobilize energy reserves, or maintain normal glucose concentrations)
overproduction: Cushing’s disease (excessive breakdown of tissue proteins and lipid reserves, impaired glucose metabolism)
E, NE malfunctions
overproduction: pheochromocytoma (high metabolic rate, body temp, and heart rate; elevated glucose levels)
estrogens malfunctions
underproduction: hypogonadism (sterility, lack of secondary sex characteristics)
overproduction: adrenogenital syndrome (overproduction of androgens by zona reticularis of adrenal cortex, leads to masculinization), Precocious puberty (premature sexual maturation
androgens malfunctions
underproduction: hypogonadism (sterility, lack of secondary sex characteristics)
overproduction: adrenogenital syndrome (abnormal production of estrogen due to adrenal or interstitial cell tumors, leads to breast enlargement), Precocious puberty (premature sexual maturation
adipose tissue
produces leptin (feedback control of appetite) -leptin must be present for normal levels of GnRH and gonadotropin synthesis
growth requires which hormones?
GH, thyroid hormones (nervous system development before & after birth), insulin, PTH and calcitrol (for strong bones), and reproductive hormones
general adaptation syndrome (GAS)
AKA: stress response.. 3 phases: alarm phase, resistance phase, and exhaustion phase
Alarm phase
immediate response to stress.
- fight or flight..
- Epinephrine is dominant hormone
- inc alertness, energy usage, heart & respiratory rate, sweat secretion
- dec digestive activity and urine production
- circulation changes, mobilization of glycogen & lipid reserves
Resistance phase
- long term stress response.. stress that lasts > a few hours
- conserve glucose
- conserve salts & water
- mobilize remaining energy reserves
exhaustion phase
- begins after weeks or months of resistance phase
- exhaustion of lipid reserves
- structural or functional damage to vital organs
- inability to produce glucocorticoids
- failure of electrolyte imbalance
- fatal unless corrected immediately