adrenal gland (10)

Question 1

is the total loss of the adrenal cortex life threatening? what about of the adrenal medulla?

Answer 1

life threatening for the loosing cortex, not medulla

Question 2

what 2 zones produce glucocorticoids & androgen?

Answer 2

zona fasciculata & zona reticularis

Question 3

what 4 hormones are secreted from the adrenal medulla?

Answer 3

epi, norepi, dopa and domapine

Question 4

what is the precursor for all the adrenal cortex hormones?

Answer 4

cholesterol

Question 5

what step is the rate limiter hormone synthesis?

Answer 5

cholesterol–> pregnenolone

Question 6

what enzyme is needed for the synethesis of DHEA and androgen?

Answer 6

17,20 desmolase

Question 7

why can’t the zona glomerulsa layer only make aldosterone?

Answer 7

because it lacks the 17-a-hydroxylase enzyme but still has aldosterone synthase

Question 8

what limits the secretion of aldosterone by the adrenal gland?

Answer 8

it is limited by the rate at which the glomerulosa cells can synthesis the hormone

Question 9

what are the 3 ways that aldosterone can be found in the serum>

Answer 9

free in plasma 37%
bound to CBG
bound to albumin

Question 10

what is the function of aldosterone?

Answer 10

stimulate kidney to reabsorb sodium & water and enhance K secretion
Does this by increasing the transcription of sodium-potassium pump and expression of apical sodium channels

Question 11

describe the form of cortisol in the plasma?

Answer 11

90% bound to cortisol binding protein (CBP)
7% bound to albumin
3% circulates “free”

Question 12

what is cortisol’s effect on ACTH and CRH?

Answer 12

downregulates them

Question 13

what is cortisol’s effect on POMC gene transcription?

Answer 13

cortisol inhibits it

Question 14

what 3 tissue types in the body respond the most to cortisol?

Answer 14

liver
skeletal muscle
adipose tissue

Question 15

list the metabolic effects of cortisol

Answer 15

• Stimulates gluconeogenesis
• Enhance protein breakdown in muscle cells to
• Stimulates lipolysis in adipose tissue
• Decreases osteoblastic activity in trabecular bone and interferes with Ca++ absorption in the gut

Question 16

describe the anti-inflammatory effects of cortisol

Answer 16

• Inhibits production of cytokines
• Inhibits production of chemo-attractant molecules
• Stabilize lysosomal enzymes
• Contributes to vasoconstriction & decrease capillary permeability
• Inhibits histamine release from mast cells

Question 17

describe the immunosuppressive effects of cortisol

Answer 17

• COX1 and COX2 are inhibited
• Inhibits histamine release from mast cells
• IL2 and its receptors are inhibited by cortisol
• Inhibits both cellular & humoral cell immunity
• Inhibits hypersensitivity reactions (esp. cell mediated)
• Decrease lymphocyte proliferation

Question 18

what is considered the most important regulator of cortisol synthesis?

Answer 18

ACTH

Question 19

what type of receptor does ACTH bind to in the adrenal gland?

Answer 19

a melanocortin-2-receptor

Question 20

where is ACTH released from?

Answer 20

anterior pituitary

Question 21

describe the mechanism of how CRH stimulates the release of ACTH

Answer 21

CRH binds to CRH receptor on a coricotroph cell→activates camp→PKA→ causes calcium influx→results in exocytosis of presynthesized ACTH

Question 22

in the anterior pituitary, what does the processing of POMC give rise to?

Answer 22

ACTH and b-lipotrophin

Question 23

what is the effect of cortisol on CRH secretion?

Answer 23

cortisol decreases the mRNA and peptide levels of CRH and inhibits the release of presynthezied CRH

Question 24

when are cortisol levels in the blood the highest? the lowest?

Answer 24

highest in the early morning. lowest in the evening

Question 25

what does major stress do to cortisol levels?

Answer 25

enhance CRH secretion→enhanced ACTH secretion→increase cortisol

Question 26

what does depression do to cortisol levels? hypoglycemia?

Answer 26

both increase cortisol levels

Question 27

what is the most common form of a congenital adrenal hyperplasia

Answer 27

21-a-hydroxylase deficiency

Question 28

what are the effects of 21-a-hydroxylase deficiency?

Answer 28

- “salt loosing” & dehydration & hypotension from decreased Aldosterone synthesis - hypoglycemia & increased size of adrenal gland from decreased cortisol feedback - increased androgen production so ambiguous genitalia in females and males go through early puberty

Question 29

how do you diagnose 21-a-hydroxylase deficiency?

Answer 29

there will be elevation of 17-hydroxyprogesterone before & after ACTH stimulating test -also diagnosis should be confirmed with molecular genetic analysis of CYP21 gene

Question 30

what hormones are affected in a 17-a-hydroxylase?

Answer 30

reduced cortisol and androgen levels | aldosterone levels will be normal or increased

Question 31

how come in a 17-a-hydroxylase deficiency you dont get hyperglycemia?

Answer 31

you still have activecorticosterone | it has a much weaker effect than cortisol, but still some effect

Question 32

what is the name of the syndrome caused by too much cortisol activity?

Answer 32

cushing syndrome

Question 33

list 3 things that could cause cushing's syndrome

Answer 33

1. This can occur if patient uses too much exogenous glucocorticoids (Prolonged use of immunosuppresants- ex prednisone) 2. ACTH producing hormones 3. Adrenal tumors

Question 34

what is the difference between cushing syndrome and cushings disease?

Answer 34

disease- only caused by ACTH producing tumors | syndrome- multitude of causes

Question 35

in cushing syndrome, what is the affect on androgens?

Answer 35

there is too much androgen

Question 36

why is "moonface" seen in patients with cushing's syndrome?

Answer 36

because cortisol promotes fat deposition in the face

Question 37

what is dexamthesone?

Answer 37

it is a potent synthetic form of glucocorticoid that is used in a diagnostic test for cushings?

Question 38

if a patient has high cortisol and low ATCH after a dexamethaone test, what does this mean?

Answer 38

adrenal tumor

Question 39

if a patient has high cortisol and high ATCH after a dexamethaone test, what does this mean?

Answer 39

ACTH producing hormone

Question 40

what is addison's disease?

Answer 40

hypoadrenal function

Question 41

what are the two most commons of addison's disease?

Answer 41

autoimmune disease or TB infection

Question 42

what does the lack of aldosterone in addison's disease lead to?

Answer 42

hypotension and hyperkalemia