Phys - Adrenal Glands

Question 1

Adrenal glands

• location
• two main portions

Answer 1

• superior to kidney
• cortex (outside layer)
• medulla (inside layer)

Question 2

Adrenal medulla

• what percent of adrenal mass
• composed of what

Answer 2

• 28% of adrenal mass

- mass of sympathetic ganglia (SNS postgang. cell without axons)

Question 3

Cells related to adrenal medulla

Answer 3

• Chromaffin cells

- paraganglia cells

Question 4

Chromaffin cells

Answer 4

• granular secretory cells
• 90% secrete epinephrine
• 10% secrete NE
• modified postgang sympathetic neuron

Question 5

Paraganglia cells

Answer 5

• near adrenal gland, function like adrenal gland

- near thoracic and abdominal sympathetic ganglia

Question 6

What is secreted by the adrenal medulla?

Answer 6

catecholamines

• epinephrine
• norepinephrine
• dopamine

Question 7

How is catecholamine release stimulated?

Answer 7

• SNS pregang release ACh
• ACh received by medullary cells, opens ca channels, ca influx, exocytosis of granules
• E and NE released into circulation

Question 8

Catecholamine synthesis

- progression of molecules

Answer 8

Tyrosine - Dopa - Dopamine - NE - E

Question 9

Catecholamine synthesis

- steps

Answer 9

• PMNT converts NE to E
• PMNT activity increased by glucocorticoids (cortisol)
  = cortisol increases epinephrine synthesis

Question 10

what is the half life of epinephrine?

Answer 10

2 minutes

Question 11

Catecholamine receptors

• type
• what process do they use

Answer 11

• adrenergic transmembrane receptors (alphas and betas)

- use second messengers

Question 12

Alpha 1 receptor action

Answer 12

• vasoconstriction
• increased peripheral resistance
• increased blood pressure
• mydriasis
• increased closure of bladder’s internal sphincter

Question 13

alpha 2 receptor action

Answer 13

• inhibition of NE release
• inhibition of ACh release
• inhibition of insulin release

Question 14

beta 1 receptor action

Answer 14

• tachycardia
• increased lipolysis
• increased myocardial contractility
• increased renin release

Question 15

beta 2 receptor action

Answer 15

• vasodilation
• slightly decreased peripheral resistance
• bronchodilation
• increased muscle and liver glycogenolysis
• increased glucagon release
• relaxed uterine smooth muscle

Question 16

Dopamine

• how much released
• MoA
• action

Answer 16

• low amounts
• increases cAMP
• vasodilation, diuresis and naturesis

Question 17

catecholamine release

Answer 17

• low basal secretion
• diffuse SNS discharge as a result of stress
• works with SNS and adrenal cortex secretion for systemic readiness for stress

Question 18

Two other hormones released from adrenal medulla

Answer 18

• metenkephalin

- adrenomedullin

Question 19

Metenkephalin

Answer 19

• opioid peptide
• binds opioid receptors and opioid growth factor receptors
• important in tissue growth and repair
• most from adrenal medulla

Question 20

Adrenomedullin

Answer 20

• potent vasodilator

- unknown significance

Question 21

Adrenal cortex structure

• main cell type
• secretions

Answer 21

• adrenocortical cells: large, lipid laden cells
• Secretes steroid hormones:
• mineralocorticoids
• glucocorticoids
• androgens

Question 22

Adrenal cortex zones (3)

Answer 22

• zona glomerulosa (aldosterone, mineralocorticoid)
• zona fasciculata (cortisol and androgens)
• zona reticularis (cortisol and androgens)

Question 23

Steroid biosynthesis

Answer 23

• cholesterol is precursor

- taken up from LDL via LDL-receptor on adrenocortical cells

Question 24

Three steroid products of cholesterol

Answer 24

• aldosterone
• cortisol
• testosterone

Question 25

Cortisol - transport - half life - metabolism

Answer 25

- bound to corticosteroid binding globulin (CBG) - half life 60-90 min (long) - metabolized by liver

Question 26

Aldosterone - transport - half life

Answer 26

- some bound, mostly free | - 20 min half life

Question 27

Androgens - transport - half life

Answer 27

- sex hormone-binding globulin (SHBG) and albumin | - half life is days (want to maintain sexual characteristics)

Question 28

Glucocorticoids - stimulus - pattern of release

Answer 28

- ACTH due to hypothalamic CRH | - diurnal release and bursts dt eating and activity

Question 29

glucocorticoids receptor

Answer 29

- intracellular - alters transcription - present on most body cells

Question 30

glucocorticoid action

Answer 30

- metabolism of glucose - increases blood sugar levels for brain and heart (anti-insulin) - hepatic gluconeogenesis and glycogenolysis - fatty acid metabolism - protein catabolism

Question 31

What is the "permissive action" of glucocorticoids?

Answer 31

- enhances biological activity of glucagon and catecholamines - ex: vasoconstriction and elevation of blood pressure

Question 32

What do glucocorticoids do to the immune system

Answer 32

- nl levels promote nl function of immune system (also bone and cartilage formation) - excess levels = suppression - reduction of IL-2 decreases lymphocyte proliferation

Question 33

how is glucocorticoid release regulated?

Answer 33

negative feedback inhibition of cortisol on ACTH release

Question 34

Mineralocorticoids - primary form - release stimulus - receptor

Answer 34

- aldosterone - renin (senses low renal bp) and ACTH (minor role) - intracellular receptor, alters protein synthesis

Question 35

Mineralocorticoids | - Action

Answer 35

- Na reabsorption from filtrate by principle cells of CD - secretion of H+ and K+ - Na reabsorption from sweat, saliva, colon * *INCREASES Na in ECF, increase fluid volume, elevate bp, eliminate K

Question 36

Mineralocorticoids | - regulation

Answer 36

- renin reduction by ANP, BNP - increased Na, blood volume, bp - falling K - decreased ACTH

Question 37

Androgens - release from adrenal gland - timing of release

Answer 37

- adrenal release of androgens is minor and decreases with age - release peaks fatally and at puberty