Endocrine 4 Flashcards
What is the production, function, and regulation of calcitonin?
Produced and released: by thyroid gland parafollicular cells
Function: inhibits bone breakdown, stimulates calcium storage in bones, reduces blood calcium
Regulation:
blood (humoral): increased blood calcium
What does PTH do? What is it made of?
Increases blood Ca++
Amino-acid based
Where is PTH produced and released?
Parathyroid Glands, 3-4 tiny glands on the posterior side of thyroid
What is the function of PTH?
increase plasma Ca2+, decreased plasma PO43-, stimulates Vitamin D
How is PTH regulated?
blood (humoral): Ca2+ levels in blood, thyroid gland (calcitonin)
What is the stimulus in the PTH pathway?
Low blood Ca++
What are the targets of PTH?
Bone:
increase in Ca2+ release from bone fluid to ECF via calcium pumps in osteocytes and osteoblasts
increase in bone breakdown, Ca2+ and PO4 release via stimulation of osteoclasts
Kidneys:
increase in blood calcium retention via kidneys
decrease in blood phosphate via kidney elimination
increase in Vitamin D activation by kidneys
Small intestine (Vitamin D needed for calcium absorption in diet)
What is hyperparathyroidism?
usually by tumors -can cause bone loss, nervous system depression, muscle weakness, weak reflexes, kidney stones
can be secondary response to low blood calcium due to kidney failure
What is hypoparathyroidism?
following gland removal (thyroid surgery), or magnesium deficiency – can cause muscle spasm, nervous system excitability, convulsions, paralysis, DEATH
What is the outer and middle areas of the adrenal?
Outer- Cortex
Middle- Medulla
What does the adrenal medulla produce?
Catecholamines- Epi, Norepi
What is the target, function, and regulation of catecholamines?
Target: SNS organ targets
Functions: enhance sympathetic effects, stress regulation, blood pressure
Regulation: sympathetic nervous system
Generally speaking, what does the adrenal cortex make?
Steroid hormones
What three types of steroids are made by the adrenal cortex?
mineralocorticoids (aldosterone) glucocorticoids (cortisol) sex hormones (androgens)
What does aldosterone do?
Fluid Balance:
increases Na+ in the blood, retained from urine
decreases K+ in the blood, eliminated in urine
Water balance follows Na+ increase, blood volume increases, blood pressure increases
Aldosterone deficiency is FATAL, due to loss of blood volume.
What sex hormone is created in the adrenal cortex?
Mainly DHEA- a weak precursor to testosterone, involved in secondary sex characteristics in puberty
What is the main glucocorticoid?
Cortisol
What is the function of cortisol?
Metabolism: increase blood glucose sequester blood glucose for the brain increase protein breakdown increase fat breakdown Stress Response: permissive vasoconstriction via epinephrine/norepinephrine other effects? Immune Suppression: blocks inflammation pathways blocks antibody production
How are glucocorticoids used clinically?
Used clinically for immune suppression eg prednisone, blocks inflammation pathways and antibody production
Glucocorticoids rx to decrease overactive immune response, not effective in a pt with high-levels of glucocorticoids because may immune suppress too much
Enhances epinepherine response
How is cortisol regulated?
hormonal: CRH by hypothalamus and ACTH by anterior pituitary
neural: stress, diurnal Rhythms- highest cortisol in morning, lowest at night
What happens with hypo secretion of cortisol?
usually both mineral and glucocorticoids involved
Addison’s disease: weight loss, low blood glucose, low blood ions, dehydration, hypotension
What happens with excess cortisol?
anterior pituitary tumors, other tumors, glucocorticoid treatment for immune diseases – can mimic diabetes with persistent elevation in blood glucose, muscle and bone loss, water and salt retention, edema, high blood pressure
Cushing’s syndrome: “moon face”, increased abdominal and back of the neck fat, chronic infections, muscle and bone weakening
What is the neural response to stress?
SNS activation
What is the endocrine response to stress?
support brain, provide building blocks for tissue repair, increase blood glucose, breakdown fat, breakdown protein increase blood volume, blood pressure enhance learning and memory circuits Epinephrine (adrenal medulla) Cortisol (adrenal cortex) ACTH (anterior pituitary) Vasopressin (posterior pituitary) Angiotensin (kidneys) inhibition of Insulin (pancreas) stimulation of Glucagon (pancreas)
What are the physiologic functions of short-term stress?
increased heart rate, increased blood pressure, increased blood glucose, increased metabolism, inhibits digestion, inhibits urine output
SNS Epinephrine/Norepinephrine
Adrenal Medulla Epinephrine/Norepinephrine
What are endocrine functions of long-term stress?
water and salt retention, long term increase in blood pressure and blood volume, long-term suppression of the immune system, increased protein and fat breakdown, long-term increase if blood glucose
CRH ACTH Adrenal Cortex: aldosterone and cortisol
What is the function, production site, target, and regulation of melatonin?
melatonin: induces sleep at night (or in the dark)
Produced and released by: The Pineal Gland
Function: induces sleep
Other Proposed functions: inhibits reproduction, seasonal changes in behavior, antioxidant defenses, anti-aging, increased immune function
Regulated
neural: light/dark input from the retina produces melanopsin, cells signal to hypothalamus
How does insulin function?
lowers blood glucose by allowing cells to transport glucose in
amino-acid based
glucose uptake in muscle and fat cells, glycogen storage, inhibit glucose production
How is insulin regulated?
blood (humoral): levels of nutrients in blood
neural: PSNS post-eating (inhibited by SNS)
hormonal: increased by glucagon, epinephrine, thyroxine, glucocorticoids, decreased by somatostatin
What are the endocrine cells of the pancreas?
alpha (α) cells - glucagon
Beta cells (β) - insulin
delta cells (D) - somatostatin
F cells – pancreatic polypeptide
What are the exocrine cells of the pancreas?
acinar cells - digestive enzymes
duct cells – NaHCO3 solution
How does insulin lower blood glucose?
production and storage of glycogen in liver and muscle
increase glucose transport into cells
inhibit glycogen breakdown and gluconeogenesis in liver
How does insulin lead to the storage of fat?
production and storage of triglycerides
increase transport fatty acids into adipose tissue
inhibit triglyceride breakdown
How does insulin lead to the storage of protein?
production and storage of protein
increase transport of amino acids into cells
inhibit protein breakdown
What is the function of glucagon? Where is it produced?
Produced and released by: pancreas
Functions: glucose synthesis, glucose release, glycogen breakdown
How is glucagon regulated?
blood (humoral): low levels of blood glucose
neural: stimulated by SNS
hormonal: inhibited by insulin and somatostatin
