Adrenal gland

Question 1

What acts on the adrenal gland

Answer 1

Renin-angiotensin system and autonomic nervous system

Question 2

Medulla function

Answer 2

secretes catecholamines eg adrenaline (noradrenaline)

Acts on alpha and beta adrenergic receptors to incr HR and RR
Acute stress response

Question 3

Cortex function

Answer 3

Releases aldosterone (mineralcorticoid): Na+ reabsorption (NA+ leads, H2O follows), incr BV as a result

Releases Glucocorticoids eg cortisol: via glucocorticoid receptors- regulate gene transcription, mobilize glucose into the blood

Question 4

adrenal glands overall function

Answer 4

mediating response to acute and chronic stress

Question 5

What is acting on glucocorticoids

Answer 5

Hypo (CRH) –> Pituitary (ACTH)

Question 6

Medulla structure

Answer 6

modified sympathetic ganglion

Question 7

Outer cortex 3 zones

Answer 7

ZG- mineralocorticoid- aldosterone

ZF- glucorticoid or corticosteroid- cortisol

ZR- androgen precursors

Question 8

Mineralcorticoids effects

Answer 8

blood volume/sodium effects

Question 9

Glucocorticoids effects

Answer 9

metabolic effects

Question 10

Catecholamines effects

Answer 10

bodily symptoms

Question 11

Regulation of secretion in the adrenal medulla

Answer 11

adrenal medulla is part of the sympathetic division of the autonomic nervous system
Considered as specialised group of postganglionic neurones
Secretion of hormones controlled by sympathetic preganglionic nerve fibres

Question 12

Effects of medullary catecholamines

Answer 12

same as direct activation of symp nerves but:

• lasts longer
• effects generalised to all cells with alpha and/or beta receptors (GPCRs)

Major effect is on CO and cellular metabolism due to greater effect of adrenaline than NA at beta receptors

Question 13

action of adrenaline vs noradrenaline

Answer 13

Noradrenaline has a more specific action working mainly on alpha receptors to increase and maintain blood pressure whereas epinephrine has more wide-ranging effects. Norepinephrine is continuously released into circulation at low levels while epinephrine is only released during times of stress.

Question 14

Specific effects of catecholamines

Answer 14

• incr release of glucose from liver
• incr release of fatty acids from fat stores
• incr HR
• incr constriction of visceral BVs
• incr BP
• Incr metabolic rate in skeletal muscles

Question 15

Precursor of aldosterone

Answer 15

Cholesterol

Corticosterone

Question 16

Actions of aldosterone

Answer 16

Stimulates reabsorption of Na+/excretion of K+ in cortical collecting ducts
Decr ratio of Na+ to K+ in sweat and saliva
Increases reabsorption of Na+ in the colon and excretion of K+ in the faeces

Overall retain Na+ and lose K+
Net effect incr in plasma vol and hence cardiovascular pressure

Question 17

How does incr aldosterones increase NA+ reabsoprtion in the cortical collecting ducts

Answer 17

Increased synthesis of Na+ channels which move Na+ from tubular lumen into ccd cells (ATPase pump moves Na+ into ISF)

Question 18

Renin-Angiotensin system

—-vanders

Answer 18

see kidney/CV lectures

BP drop- renin produced from kidney, travels in blood to the liver.

Angiotensinogen is produced by the liver, and is then broken up by renin, an enzyme produced in the kidney, to form angiotensin I.
This travels to the lungs, where the angiotensin converting enzyme converts Angiotensin I to to II

Angiotensin II acts on the adrenal cortex to produce aldosterone, leading to more Na+ reabsorption , incr BV etc which incr BP

Incr BP feeds back -vely to reduce renin secretion

Question 19

Aldosterone anatgonist

Answer 19

Spironolactone: potassium-sparing diuretic hyperaldosteronism (Conn’s disease)

Question 20

ACE inhibitors

Answer 20

Captopril, enalapril
Anti-hypertensive
Cardiac failure

Question 21

ATII antagonist

Answer 21

Losartan

Similar to ACE inhibitors, used in hypertension

Question 22

Common structure in all steroids

Answer 22

tetraplanar ring

Question 23

Glucorticoids precursor

Answer 23

cholesterol

Question 24

How are most glucorticoids transported

Answer 24

Bound to binding proteins

Question 25

Regulation of glucorticoid secretion

Answer 25

Hypo, in response to stress releases CRH which acts on pituitary gland to produce ACTH, which acts on adrenal glands to produce cortisol, circulates and acts on tissues

Negative feedback - cortisol switches off pituitary production of ACTH and hypo production of CRH

Question 26

CRH

Answer 26

corticotrophin releasing hormone

Question 27

ACTH

Answer 27

adreno cortico Trophic hormone

Question 28

Fluctuations in cortisol are caused by

Answer 28

fluctuations in ACTH secretion from the pituitary gland

Leads to circadian rhythm

Question 29

Metabolic actions of glucorticoids

Answer 29

Stimulate gluconeogenesis in the liver- incr plasma glucose
Incr proteolysis in the muscle- creates AA’s which act as substrates for generation of glucose in the liver
Lipolysis of fat- incr glycerol production - alternative substrate for glucose so incr plasma glucose. Incr FFA production acts as fuel source for muscle and liver

Question 30

Addison’s disease- cortisol deficiency

Answer 30

cellular metabolism: hypoglycaemaia, weight loss
CV: vasodilation, hypotension, reduced BV, anaemia and lymphocytosis
CNS: fatigue and anorexia
Salt balance: reduced Na, incr K (mineralcortocoid loss)
Inflammatory and immune system: tendency towards autoimmune disease

Question 31

Corticosteroids

Answer 31

Cause rise in plasma glucose levels (release from liver and incr gluconeogenesis)

Causes incr in proteolysis, which can bring about muscle wasting skin thinning
Cause fat redistribution eg moon face (Cushings)
Cause incr breakdown of triglycerides, leading to rise in plasma Fatty acid levels

SUppress inflammation and immune responses

Question 32

Cushing’s disease- cortisol excess

Answer 32

cellular metabolism: hyperglycaemia, fat redistribution, truncal obesity. Weak muscles, skin and bone and poor wound healing
CV: hypertension, incr BV, leukocytosis, erthyrocytosis
CNS: depression,euphoria
Salt balance: incr NA, decr K (more mineralocorticoid)
Inflammatory and immune response: decr inflam response, incr infection and decr fibrous tissue formation