Adrenal Gland

Question 1

How do catcholamines affect beta-2 receptors and what are their functions?

Answer 1

Found: Salivary glands, adipose, kidney vascular smooth muscle of heart, GIT walls + bladder, bronchioles

Activation: Activates G-Pot. -> Activates Adenyl-cyclase -> Activates cAMP

Function = relax, dilation

Question 2

How do catcholamines affect beta-1 receptors and what are their functions?

Answer 2

Found: Heart

Activation: Activates G-Pot. -> Activates Adenyl-cyclase -> Activates cAMP

Function = Increases Heart rate and contractility

Question 3

How do catcholamines affect alpha-2 receptors and what are their functions?

Answer 3

Found: GIT walls, pre-synaptic adrenergic nerve terminals (inhibits NA), liver platelets, blood vessels smooth muscle

Activation: Activates G-Pot. -> Inactivates Adenyl-cyclase -> inactivates cAMP

Function = Platelet aggregation + blood vessel constriction

Question 4

How do catcholamines affect alpha-1 receptors and what are their functions?

Answer 4

Found: vascular smooth muscle of skin + gut, GIT sphincters, bldder, iris radial muscle.

Activation: Activates G-Pot. -> Phospholipase C -> Increase intracellular Ca2+

Function = Contraction

Question 5

Describe the processes which control the release of mineralocorticoids from the adrenal cortex.

Answer 5

Aldosterone:

• Decreased [Na+]/Increased [K+] or Decreased BP
• Aldosteron increases sodium reabsortion and potassium excetion
• Increases BP and ECF volume.
• RAA system: Renin released -> angiotensinogen released.
• Antiotensin I -> Angiotensin II
• = Aldosterone Released.

Question 6

Where is Aldosterone synthesised?

Answer 6

Zona glomerulosa

Question 7

Where is cortisol synthesised?

Answer 7

Zona fasiculata (mostly) and Zona reticularis

Question 8

Is aldosterone essential for life?

Answer 8

Yes, without, a person rapidly dies from circulatory shock

Question 9

Describe the processes which control the release of glucocorticoids from the adrenal cortex.

Answer 9

• Inputs of Circadian rhythms or stress ->
• Corticotropin releasing hormone (CRH) from hypothalamus
• Adrenocortico releasing hormone from anterior pituitary
• Releases cortisol from adrenal medulla

1. Immune system = Suppressed
2. Liver = Gluconeogenesis
3. Muscle = Protein catabolism
4. Adipose Tissue = Lipolysis

Question 10

Describe in detail the mode of action of aldosterone at its target cell.

Answer 10

• Aldosterone = Lipid soluble hormone = Diffuses past membrane into cell.
• Binds to intracellular receptor -> Stimulates gene expression
• New protein channels + pumps are made
• Aldosterone-induced proteins modify the existing proteins
• Increases Na+K+-ATPase pumps in basolateral membrane of DCT
• Increases Na+ channels in luminal membrae of DCT