Adrenal Medulla and Cortex

Question 1

Adrenal glands are located where?

Answer 1

in the retroperitoneal cavity above each kidney

Question 2

The adrenal cortex produces what?

Answer 2

• mineralcorticoids
• glucocorticoids
• androgens

Question 3

The adrenal medulla produces what?

Answer 3

• epinephrine
• norepinephrine

Question 4

Where is the adrenal medulla located?

Answer 4

in the inner zone of the gland and surrounded by the cortex

Question 5

Chromaffin cells of the adrenal medulla secrete what?

Answer 5

catecholamines (epi and NE)

Question 6

Epi acts on which adrenergic receptors?

Answer 6

all alpha and beta adrenergic receptors

Question 7

NE acts on which adrenergic receptors?

Answer 7

alpha 1 and 2, beta 1

Question 8

How is the adrenal medulla considered a specialized sympathetic ganglion?

Answer 8

receives input from sympathetic nervous system via preganglionic fibers originating in the thoracic spinal cord

Question 9

What is the predominant catecholamine synthesized?

Answer 9

epinephrine

Question 10

Epi is stored in granules and released when activated by what?

Answer 10

SNS

Question 11

What enzyme converts NE to Epi under the influence of cortisol?

Answer 11

phenylethanolamine-N-methyltransferase (PNMT)

Question 12

All Epi originates from where?

Answer 12

adrenal medulla

Question 13

Most NE originates from where?

Answer 13

sympathetic nerve terminals and brain

Question 14

What are the target tissues of catecholamines?

Answer 14

• muscle cells
• liver

Question 15

Most metabolism of catecholamines occurs where?

Answer 15

• liver
• kidneys

Question 16

What are the effects of catecholamines?

Answer 16

• increased HR, cardiac output, BP
• redistribution of blood toward skeletal muscle
• increased respiration
• increased blood glucose

Question 17

What are the zones of the adrenal cortex?

Answer 17

• zona glomerulosa
• zona fasciculata
• zona reticularis

Question 18

What is the major hormone secreted by the zona glomerulosa?

Answer 18

aldosterone

Question 19

What are the major hormones secreted by the zona fasciculata?

Answer 19

• cortisol in humans, dogs, cats, sheep, cows, pigs, horses
• cortisterone in rats, mice, rabbits

Question 20

What are the major hormones secreted by the zona reticularis?

Answer 20

androgen precursors (dehydroepiandrosterone and androstendione)

Question 21

What is the precursor for all steroids?

Answer 21

cholesterol

Question 22

What is the rate limiting step of steroid hormone production?

Answer 22

conversion of cholesterol to pregnenolone (first step)

Question 23

Steroid hormone production is catalyzed by what system in mitochondria and endoplasmic reticulum?

Answer 23

cytochrome P450

Question 24

All layers of the adrenal cortex have what enzyme?

Answer 24

cholesterol desmolase

Question 25

The direction of steroid hormone production pathway depends on what?

Answer 25

presence/absence of enzymes to catalyze modifications

Question 26

What is the site of production for mineralcorticoids (aldosterone)?

Answer 26

zona glomerulosa

Question 27

The production of mineralcorticoids requires what?

Answer 27

- ACTH to stimulate cholesterol desmolase - aldosterone synthase

Question 28

Primary regulation of aldosterone occurs via what?

Answer 28

- changes in ECF volume via RAAS - changes in blood potassium

Question 29

Describe regulation of aldosterone secretion by RAAS.

Answer 29

- mediator is angiotensin II 1. decrease in ECF volume 2. decrease in renal blood perfusion pressure 3. increases renin secretion by kidney - ultimately, aldosterone stimulates Na reabsorption by kidney to restore ECF volume

Question 30

Describe regulation of aldosterone secretion by increases in blood K+ concentration.

Answer 30

depolarizes adrenal cells to open Ca channels to stimulate aldosterone secretion --> increase K+ excretion in kidneys

Question 31

What is the site of production for glucocorticoids (cortisol)?

Answer 31

Zona fasciculata

Question 32

What is the first step in producing glucocorticoids?

Answer 32

catalyzation by 17 alpha-hydroxylase

Question 33

What is the purpose of the final enzyme (11 beta-hydroxylase) in glucocorticoid production?

Answer 33

converts 11-deoxycortisol to cortisol

Question 34

The production of glucocorticoids requires ACTH to do what?

Answer 34

stimulate cholesterol desmolase

Question 35

Cortisol is regulated by what?

Answer 35

hypothalamic-pituitary-adrenal axis

Question 36

Cortisol is transported in blood by what?

Answer 36

transcortin

Question 37

Cortisol is metabolized by ____, and excreted in urine using _____ (kidney).

Answer 37

liver, glucuronides

Question 38

What are the stimulators of ACTH secretion?

Answer 38

- stress (hypoglycemia, infections/fevers) - low cortisol - ADH

Question 39

What are the inhibitors of ACTH secretion?

Answer 39

- high cortisol - exogenous steroids - somatostatin - dopamine

Question 40

Does cortisol have long or short loop feedback to inhibit ACTH release?

Answer 40

long loop feedback

Question 41

What type of feedback does cortisol have to inhibit ACTH synthesis?

Answer 41

slow feedback

Question 42

Does cortisol have long or short loop feedback to block CRH release from hypothalamus?

Answer 42

long loop feed back

Question 43

What type of feedback does ACTH have to inhibit CRH release?

Answer 43

short loop feedback

Question 44

What is the mechanism of action of cortisol at tissue level?

Answer 44

- cortisol binds type II glucocorticoid receptor in cytosol - receptor hormone complex moves into nucleus and binds another receptor on DNA (DNA response element) - activate gene transcription and translation

Question 45

Why are the effects of cortisol described as "permissive"?

Answer 45

- does not directly initiate actions but allows critical processes to occue - amplifies actions of other hormones

Question 46

Which type of cortisol is biologically active?

Answer 46

only free cortisol

Question 47

Are the net effects of cortisol anabolic or catabolic?

Answer 47

catabolic

Question 48

What are the effects of cortisol on energy metabolism?

Answer 48

- increases blood glucose - increases glycogenesis - increases lipolysis and protein catabolism - increases appetite, visceral obesity

Question 49

What are the effects of cortisol on musculoskeletal system?

Answer 49

- increases protein catabolism - inhibits bone formation - increases bone resorption - causes osteoporosis - inhibits collagen synthesis - causes thin skin and fragile capillaries

Question 50

What are the effects of cortisol on kidneys and cardiovascular system?

Answer 50

- increases glomerular filtration rate in kidney and decreases ADH for water balance - helps maintain normal blood pressure and volume - up regulates alpha 1 adrenergic receptors which is necessary for vasoconstrictive response of arterioles to NE and Epi

Question 51

What are the effects of cortisol on the immune system?

Answer 51

- suppresses immune system by suppressing prostaglandins, thromboxanes, leukotrienes - decreases neutrophil activity, formation of cytokines, T-lymphocytes, and antibody formation - specific anti-inflammatory effects including: induces lipocortin, inhibits production of interleukin-2, and inhibits release of histamine

Question 52

What is the innermost cortical layer?

Answer 52

zona reticularis

Question 53

The zona reticularis produces what?

Answer 53

weak androgens: DHEA, DHEA sulfate, androstenedione

Question 54

What enzyme is needed for the androgen pathway?

Answer 54

17, 20-lyase

Question 55

What are some adrenal cortex dysfunctions?

Answer 55

- cushings syndrome (hyperadrenocorticism) - addision's disease (hypoadrenocorticisim) - hyperaldosteronism - alopecia X (atypical hyperadrenocorticism)

Question 56

What are causes of cushings syndrome (hyperadrenocorticism)?

Answer 56

- pituitary dependent hyperadrenocorticism (PDH) with bilalteral adrenal hyperplasia - pars intermedia dysfunction - adrenal tumors - iatrogenic hyperadrenocorticism resulting from chronic excessive exogenous steroid administration

Question 57

What are causes of addisons disease (hypoadrenocorticism)?

Answer 57

- autoimmune - infiltrative disease (cancers) - idiopathic - iatrogenic steroids

Question 58

Addisions disease results in losses of what?

Answer 58

- aldosterone - cortisol

Question 59

Alopecia X is characterized by what?

Answer 59

elevation in androgens and/or sex hormones

Question 60

What are causes of primary hyperaldosteronism?

Answer 60

- idiopathic adrenal hyperplasia (bilateral) - tumor (unilateral or bilateral)

Question 61

What are causes of secondary hyperaldosteronism?

Answer 61

- liver disease - kidney disease (activating RAAS)