Endocrine 4 Flashcards by Matt Bresnahan

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

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What does PTH do? What is it made of?

Increases blood Ca++

Amino-acid based

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Where is PTH produced and released?

Parathyroid Glands, 3-4 tiny glands on the posterior side of thyroid

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What is the function of PTH?

increase plasma Ca2+, decreased plasma PO43-, stimulates Vitamin D

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How is PTH regulated?

blood (humoral): Ca2+ levels in blood, thyroid gland (calcitonin)

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What is the stimulus in the PTH pathway?

Low blood Ca++

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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)

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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

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What is hypoparathyroidism?

following gland removal (thyroid surgery), or magnesium deficiency – can cause muscle spasm, nervous system excitability, convulsions, paralysis, DEATH

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What is the outer and middle areas of the adrenal?

Outer- Cortex

Middle- Medulla

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What does the adrenal medulla produce?

Catecholamines- Epi, Norepi

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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

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Generally speaking, what does the adrenal cortex make?

Steroid hormones

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What three types of steroids are made by the adrenal cortex?

mineralocorticoids (aldosterone)
glucocorticoids (cortisol) 
sex hormones (androgens)

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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.

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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