Endocrine 4

Question 1

What is the production, function, and regulation of calcitonin?

Answer 1

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

Question 2

What does PTH do? What is it made of?

Answer 2

Increases blood Ca++

Amino-acid based

Question 3

Where is PTH produced and released?

Answer 3

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

Question 4

What is the function of PTH?

Answer 4

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

Question 5

How is PTH regulated?

Answer 5

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

Question 6

What is the stimulus in the PTH pathway?

Answer 6

Low blood Ca++

Question 7

What are the targets of PTH?

Answer 7

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)

Question 8

What is hyperparathyroidism?

Answer 8

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

Question 9

What is hypoparathyroidism?

Answer 9

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

Question 10

What is the outer and middle areas of the adrenal?

Answer 10

Outer- Cortex

Middle- Medulla

Question 11

What does the adrenal medulla produce?

Answer 11

Catecholamines- Epi, Norepi

Question 12

What is the target, function, and regulation of catecholamines?

Answer 12

Target: SNS organ targets
Functions: enhance sympathetic effects, stress regulation, blood pressure
Regulation: sympathetic nervous system

Question 13

Generally speaking, what does the adrenal cortex make?

Answer 13

Steroid hormones

Question 14

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

Answer 14

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

Question 15

What does aldosterone do?

Answer 15

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.

Question 16

What sex hormone is created in the adrenal cortex?

Answer 16

Mainly DHEA- a weak precursor to testosterone, involved in secondary sex characteristics in puberty

Question 17

What is the main glucocorticoid?

Answer 17

Cortisol

Question 18

What is the function of cortisol?

Answer 18

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

Question 19

How are glucocorticoids used clinically?

Answer 19

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

Question 20

How is cortisol regulated?

Answer 20

hormonal: CRH by hypothalamus and ACTH by anterior pituitary
neural: stress, diurnal Rhythms- highest cortisol in morning, lowest at night

Question 21

What happens with hypo secretion of cortisol?

Answer 21

usually both mineral and glucocorticoids involved

Addison’s disease: weight loss, low blood glucose, low blood ions, dehydration, hypotension

Question 22

What happens with excess cortisol?

Answer 22

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

Question 23

What is the neural response to stress?

Answer 23

SNS activation

Question 24

What is the endocrine response to stress?

Answer 24

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)

Question 25

What are the physiologic functions of short-term stress?

Answer 25

increased heart rate, increased blood pressure, increased blood glucose, increased metabolism, inhibits digestion, inhibits urine output
SNS Epinephrine/Norepinephrine
Adrenal Medulla  Epinephrine/Norepinephrine

Question 26

What are endocrine functions of long-term stress?

Answer 26

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

Question 27

What is the function, production site, target, and regulation of melatonin?

Answer 27

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

Question 28

How does insulin function?

Answer 28

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

Question 29

How is insulin regulated?

Answer 29

blood (humoral): levels of nutrients in blood

neural: PSNS post-eating (inhibited by SNS)
hormonal: increased by glucagon, epinephrine, thyroxine, glucocorticoids, decreased by somatostatin

Question 30

What are the endocrine cells of the pancreas?

Answer 30

alpha (α) cells - glucagon
Beta cells (β) - insulin
delta cells (D) - somatostatin
F cells – pancreatic polypeptide

Question 31

What are the exocrine cells of the pancreas?

Answer 31

acinar cells - digestive enzymes

duct cells – NaHCO3 solution

Question 32

How does insulin lower blood glucose?

Answer 32

production and storage of glycogen in liver and muscle
increase glucose transport into cells
inhibit glycogen breakdown and gluconeogenesis in liver

Question 33

How does insulin lead to the storage of fat?

Answer 33

production and storage of triglycerides
increase transport fatty acids into adipose tissue
inhibit triglyceride breakdown

Question 34

How does insulin lead to the storage of protein?

Answer 34

production and storage of protein
increase transport of amino acids into cells
inhibit protein breakdown

Question 35

What is the function of glucagon? Where is it produced?

Answer 35

Produced and released by: pancreas

Functions: glucose synthesis, glucose release, glycogen breakdown

Question 36

How is glucagon regulated?

Answer 36

blood (humoral): low levels of blood glucose

neural: stimulated by SNS
hormonal: inhibited by insulin and somatostatin