Anatomy

Question 1

name the zones of the cortex outside to inside

Answer 1

glomerulosa
fasiculata
reticularis

Question 2

what is produced in the ZG?

Answer 2

MC (aldo)

Question 3

how is the ZG regulated?

Answer 3

by K and angiotensin II; ACTH acutely but not chronically (thus, does not atrophy when ACTH axis fails)

Question 4

what is produced in the ZF and ZR?

Answer 4

GCs (cortisol) and androgens resp.

Question 5

how are the ZF and ZR regulated

Answer 5

ACTH (thus atrophies when the ACTH axis fails)

Question 6

how is production/release regulated

Answer 6

at the level of production, b/c once produced they are released

Question 7

what is the rate limiting step (RLS?) in the synthesis of steroids?

Answer 7

formation of pregnenolone

Question 8

how is steroid synthesis regulated?

Answer 8

ACTH acts on cAMP which controls StAR to allow cholesterol into the mitochondria

Question 9

what are the features of the HPA regulatory axis

Answer 9

diurnal rhythm (highest 0800) 
negative feedbac
stress response (10x)

Question 10

what is the ACTH receptor?

Answer 10

MC2R (Gs coupled) GPCR

Question 11

what is the major clinical use of ACTH

Answer 11

to test the HPA axis for ACTH; additionally for seizures and infantile spasms

Question 12

synthetic version of ACTH is called?

Answer 12

cosyntropin; AA 1-24 of the ACTH;

Question 13

dosage of cosyntropin

Answer 13

rapid IV push, measurement of cortisol levels at 30-60 minutes

Question 14

low does cosyntropin good for diagnosing what? why?

Answer 14

secondary insufficiency; without chronic low level ACTH the cortex atrophies

Question 15

high dose cosyntropin good for what?

Answer 15

differentiating enzymatic problems (eg CAH vs. 21-hydroxylase deficiency)

Question 16

feedback is mediated how?

Answer 16

through GCs (not MCs or androgens)

Question 17

where does renin come from?

Answer 17

JG cells of the macula densa

Question 18

what does renin do? when is it release?

Answer 18

conversion of angiotensinogen to angiotensin I; hypovolemia, symp stim; low flow through kidneys

Question 19

what does ATII bind to in order to stim aldo release? where?

Answer 19

AT1R; ZG cells

Question 20

aldo synth increased by

Answer 20

K and ATII; via Ca

Question 21

what do GCs ride in the plasma?

Answer 21

CBG (corticosteroid binding globulin) - 90%; albumin - 10%

Question 22

what does aldo ride?

Answer 22

nothing

Question 23

what is inactivated by the liver?

Answer 23

GCs