HPA axis, the adrenal cortex and steroid hormone synthesis

Question 1

suprarenal glands aka adrenal glands are located …

Answer 1

on top of the kidney

Question 2

what two hormones are necessary for a full response in PC

Answer 2

CRH & AVP

Question 3

Cortisol has two negative feedbacks in…

Answer 3

hypothalamic >. CRH & AVP
and AP (release of ACTH) cortcotropes

Question 4

HPA

Answer 4

1. CRH & AVP send neurons into Portal system
2. Portal system sends secondary hormones into AP stimulating corticotropes to release ACTH
3. ACTH is released and binds to ACTHR located in the cortex of the Adrenal gland
4. releasing an increase of cortisol and adrenal androgens
5. when you have enough cortisol it will start inhibiting CRH and AVP signaling and production of ACTH

Question 5

Circadian rhythm

Answer 5

Daily rhythm

Question 6

Adrenal anatomy

Answer 6

zona Glomerulosa
zona Fasciculata
Zona Reticularis

Question 7

Cortex

Answer 7

80-90% derived from mesoderm (synthesis of steroid hormones) of abdominal wall

Question 8

Medulla

Answer 8

10-20% derived from neuroectoderm (nervous system)
epinephrine & norepinephrine

Question 9

zona glomerulosa

Answer 9

mineralocorticoids (aldosterone)

Question 10

zona fasciculata

Answer 10

glucocorticoids (cortisol)

Question 11

zona reticularis

Answer 11

DHEA

Question 12

Adrenal regions have different sensitivity to ACTH

Answer 12

Zona fasciculata = hypertrophy and hyperplasia
zone reticularis = hypertrophy & hyperplasia
zona gomerulosa= no change

Question 13

Where are MC2R expressed?

Answer 13

zona Fasciculata and reticularis
NOT MEEDULLA

Question 14

When a stress activates CRH and AVP stimulating corticotropes in AP to release ACTH that binds to MC2R in the adrenal cortex …
What happens ??

Answer 14

increase of glucocorticoids (cortisol)
increase of DHEA
increase of adrenal weight (hypertrophy/hyperplasia)
increase in medullary hyperplasia (due to cortisol stimulation)

Question 15

Hypertrophy

Answer 15

increase cell growth

Question 16

Hyperplasia

Answer 16

increase cell number

Question 17

Cholesterol

Answer 17

component of lipid bilayer
biosynthesis of acetyl CoA and acetoacetyl-CoA
Liver is main source of making cholesterol itself
brain contains the most&raquo_space; myelin sheaths
Transports in blood (LDL - low density lipoprotein) – FA + hydroxyl group

Question 18

CHO is synthesized by

Answer 18

cells &laquo_space;can not supply all CHO for steroid production

Question 18

CHO interacts with GPCR and ion pumps
BUT what if you don’t have any CHO??

Answer 18

without CHO ion pumps are deactivated

Question 19

Steroidogenesis

Answer 19

synthesis of steroid hormones
main sites» adrenal cortex and gonads

Question 20

Steroids hormones are products of …

Answer 20

a series of enzymatic rxns from a common precursor cholesterol

Question 21

Cytochrome P450 Enzymes

Answer 21

oxidases with different functions + steroidogenesis
human genome 57 P450 enzyme genes
7 Mitochondrial
50 located in ER

Question 22

P450scc

Answer 22

Located in Mito
CHO side chain is cleaved

Question 23

p450c17
and p450c21

Answer 23

located in ER
adds -OH groups

Question 24

P450aldo

Answer 24

located in Mito biosynthesis of aldosterone

Question 25

3beta-HSD

Answer 25

Dehydrogenase Preg to Prog 17alphapreg-17 alpha prog DHEA to Androstenedione

Question 26

Sulfokinase

Answer 26

DHEA to DHEAS

Question 27

Cortisol very widespread actions in the body... such as

Answer 27

- regulates a lot of different processes to maintain homeostasis - a lot of different tissues express glucocorticoid receptors << receptor for cortisol

Question 28

What happens in response to Hypoglycemia

Answer 28

PVN >> CRH & AVP release into portal system - stimulates corticotropes to release ACTH - ACTH binds to MC2R in cortex of Adrenal gland - increases cortisol which stimulates liver gluconeogenesis - bring in more glucose into the blood

Question 29

effects of cortisol

Answer 29

increases blood glucose by inhibiting uptake by tissues and by gluconeogenesis - want to keep it in blood by

Question 30

effects of insulin

Answer 30

decrease blood glucose increasing uptake by tissues - want to remove it

Question 31

how do cortisol keep glucose in the blood

Answer 31

muscle: stimulates catabolism to release AA myostatin (breaks down muscle cells) Adipose tissues: stimulates lipolysis to release FA and glycerol >> activating HSL (hormone sensitive lipase) peripheral tissues inhibits glucose uptake SAVE GLUCOSE Liver stimulates gluconeogenic enzymes PEPCK >> increasing blood glucose