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Flashcards in Adrenal Physiology Deck (41)
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1

The adrenal cortex is involved in ______ hormone synthesis

Steroid
- cortisol: gluconeogenesis, anti-inflammatory (regulated by HPA axis)
- aldosterone: blood volume regulation, secretion of K and resorption of Na from kidney (regulated by RAAS)

2

Adrenal medulla is responsible for synthesizing ________

Catecholamines
- regulation via SNS

3

The zona fasiculata produces _____

- cortisol
- corticosterone

4

The zona glomerulosa produces _______

Aldosterone

5

The zona reticularis produces ________

Androstenedione

6

Corticosteroids

Refers to all hormones made in the adrenal glands
- glucocorticoids (cortisol)
- mineralcorticoids (aldosterone)
- sex steroids (progestogens, androgens, estrogens)

7

Anabolic steroids

- increased protein synthesis
- increased muscle mass
- typically androgens

8

Catabolic steroids

- decreased protein synthesis
- decreased muscle mass
- usually glucocorticoids: cortisol, prednisone

9

Adrenal gland components

- adrenal cortex (80%) --> steroid hormones
- adrenal medulla (20%) --> catecholamine synthesis, SNS regulation

10

Catecholamine synthesis

- released into blood
- fight or flight
- norepinephrine (cat)
- epinephrine (dog, human)
- increase metabolic rate
- increase blood pressure, cardiac contractility, myocardial excitablity

11

Pheochromocytoma

Tumor of adrenal medulla with excess production of catecholamines

12

Cortex components

- glomerulosa (15%)
- fasiculata (75%)
- reticularis (10%)

13

Glomerulosa

- specific enzyme: aldosterone synthase
- product: mineralocorticoids

14

Fasiculata

- specific enzyme: 17alpha-hydroxylase
- product: glucocorticoids, sex hormones

15

Reticularis

- specific enzyme: 17alpha- hydroxylase
- products: glucocorticoids, sex hormones

16

Steroids are degraded in the ______

Liver
- free hormone
- conjugated to glucuronide
- excreted thru urine, bile
- inhibited if diseased

17

Steroids are bound to proteins 94%, but only the ________ is active

Free hormone

18

Cortisol metabolism

- corticosteroid-binding globulin (CBG)
- albumin
- T1/2 < 2 hrs

19

Aldosterone metabolism

- albumin
- slightly bound
- T1/2 is 20 minutes

20

Steroidal mechanism of action

Free hormone diffuses into cell (lipophilic) --> binds cytoplasmic receptor --> translocates to nucleus, binds DNA --> directs transcription (proteins)

21

What are the cellular functions of cortisol?

- catabolic: gluconeogenesis, anti-insulin, protein
- anti-inflammatory
- anti-stress
*receptors in most cells*

22

Catabolic effects of cortisol on carbohydrates

- stimulates hepatic gluconeogenesis
- inhibits effects of insulin
- fight or flight
- protects from hypoglycemia

23

Catabolic effects of cortisol on lipids

- mobilizes fatty acids
- redistribution

24

Catabolic effects of cortisol on proteins

- inhibits cellular uptake of amino acids
- stimulates gluconeogenesis
- muscle breakdown
- skin, CT, bone

25

Anti-inflammatory/immunosuppressive function of cortisol

- stabilization of lysosomes
- decreases: capillary permeability, margination of WBCs
- suppression of T lymphocytes
- decreases fever (IL-1)
- blocks allergies
*give glucocorticoids during anaphylactic shock*

26

3 functions of cortisol

- resistance to stress
- stimulation of erythropoiesis
- maintenance of vascular tone

27

Functions of cortisol: summary

- gluconeogenesis
- protein catabolism
- stress resistance
- anti inflammatory
- immunosuppressive

28

The hypothalamic-pituitary-adrenal axis

Hypothalamus
- corticotropin releasing hormone
- physical, emotional, chemical stress
Anterior pituitary
- adrenocorticotropic hormone
Adrenal gland
- cortisol

29

Adrenocorticotropic hormone

Episodic secretion (concentration varies)
- precursor: pro-opiomelanocortin (POMC)

30

ACTH mechanism of action

Increase free cholesterol --> conversion of cholesterol to pregnenolone --> major action of ACTH --> rate-limiting step in cortisol synthesis
- trophic effect