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NPB 130 M1 > HPA axis, the adrenal cortex and steroid hormone synthesis > Flashcards

HPA axis, the adrenal cortex and steroid hormone synthesis Flashcards

1
Q

suprarenal glands aka adrenal glands are located …

A

on top of the kidney

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2
Q

what two hormones are necessary for a full response in PC

A

CRH & AVP

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3
Q

Cortisol has two negative feedbacks in…

A

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

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4
Q

HPA

A
  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
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5
Q

Circadian rhythm

A

Daily rhythm

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6
Q

Adrenal anatomy

A

zona Glomerulosa
zona Fasciculata
Zona Reticularis

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7
Q

Cortex

A

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

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8
Q

Medulla

A

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

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9
Q

zona glomerulosa

A

mineralocorticoids (aldosterone)

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10
Q

zona fasciculata

A

glucocorticoids (cortisol)

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11
Q

zona reticularis

A

DHEA

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12
Q

Adrenal regions have different sensitivity to ACTH

A

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

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13
Q

Where are MC2R expressed?

A

zona Fasciculata and reticularis
NOT MEEDULLA

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14
Q

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

A

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

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15
Q

Hypertrophy

A

increase cell growth

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16
Q

Hyperplasia

A

increase cell number

17
Q

Cholesterol

A

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

18
Q

CHO is synthesized by

A

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

18
Q

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

A

without CHO ion pumps are deactivated

19
Q

Steroidogenesis

A

synthesis of steroid hormones
main sites» adrenal cortex and gonads

20
Q

Steroids hormones are products of …

A

a series of enzymatic rxns from a common precursor cholesterol

21
Q

Cytochrome P450 Enzymes

A

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

22
Q

P450scc

A

Located in Mito
CHO side chain is cleaved

23
Q

p450c17
and p450c21

A

located in ER
adds -OH groups

24
Q

P450aldo

A

located in Mito
biosynthesis of aldosterone

25
Q

3beta-HSD

A

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

26
Q

Sulfokinase

A

DHEA to DHEAS

27
Q

Cortisol very widespread actions in the body… such as

A
  • regulates a lot of different processes to maintain homeostasis
  • a lot of different tissues express glucocorticoid receptors &laquo_space;receptor for cortisol
28
Q

What happens in response to Hypoglycemia

A

PVN&raquo_space; 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

29
Q

effects of cortisol

A

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

30
Q

effects of insulin

A

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

31
Q

how do cortisol keep glucose in the blood

A

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

NPB 130 M1 (6 decks)

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