HPA Axis and Adrenal Gland Flashcards Preview

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Flashcards in HPA Axis and Adrenal Gland Deck (80)
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1

What are the components of the HPA axis?

Hypothalamus
Pituitary
Adrenal Gland

2

What are the main functions of the HPA axis?

-Adaptive response to stress
-Regulation of immune function

3

What are the hormones of the HPA axis?

Catecholamines – epinephrine and norepinephrine

Glucocorticoids – cortisol

4

What enacts short loop inhibition on CRH?

ACTH

5

What enacts long loop inhibition on CRH?

Cortisol

6

Where is CRH made?

Parvocellular Neurons of the PVN

7

What is the release pattern of CRH?

Pulsatile so it results in periodic release of ACTH

8

What receptor does CRH use for the release of ACTH?

GPCR

9

What are the main receptors that bind CRH and what is the binding affinity?

CRH R1 - Binds with highest affinity to CRH R1 in anterior pituitary.

CRH R2 - Binds with higher affinity to urocortin.

10

What is the synergistic effect of CRH and AVP?

ACTH release is amplified in the presence of AVP and CRH together

11

What is POMC?

Pro-opiomelanocortin and it is the precursor of ACTH

12

Where is ACTH made?

Anterior PItuitary

13

What receptors does ACTH bind to and with what affinity?

Binds with high affinity to MC2R

Binds with low affinity to MC1R (skin)

14

How do high levels of ACTH causes hyper pigmentation of the skin?

It will increase MC1R binding in the skin

15

What are the 3 layers of the adrenal gland?

Capsule
Cortex
Medulla

16

What hormones does the cortex secrete??

Steroids

17

What hormones does the medulla secrete?

Catecholamines

18

What is the cell type of cortex and the medulla?

Cortex - glandular
Medulla - neural

19

What are the 3 layers of the adrenal cortex and the hormones that they produce?

Zona Glomerulosa - Mineralcorticoids
Zona Fascilculata - Glucocorticoids
Zona Reticularis - Weak Androgens (DHEA)

20

What is the blood supply of the adrenal cortex?

Suprarenal arteries break into subcapsular plexus of capillaries (fenestrated).

21

What is the blood supply of the adrenal medulla?

It has a dual blood supply.

•Bathes the medullary cells with blood carrying corticosteriods from the cortex – important for conversion of NE to E.

•Arterioles break into fenestrated capillaries.

22

What is cortisol released in response to?

Acute/chronic stress

23

Where is cortisol released from?

Zona Fasciculata

24

How is cortisol transported in the blood?

90% is bound to corticosteroid binding globulin (CBG)

25

What converts cortisone into cortisol?

11beta-HSD1

26

What is pleiotropy in cortisol?

It has different effects on different tissues.

27

What is the effect of cortisol on bone?

Increases bone resorption and decreases bone formation by decreasing IGF-I receptors.

28

What is the effect of cortisol on muscle?

Decreases muscle mass

29

What is the effect of cortisol on the immune system?

Suppresses immune and inflammatory responses

30

What are the metabolic actions of cortisol?

It is a potent counter-regulatory hormone to insulin.

-Increase gluconeogenesis and plasma glucose levels
-Increase lipolysis
-Increases proteolysis
-Redistributes fat to the abdominal area

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