L5 - Adrenal Medulla

Question 1

Hypo function:

Hyper function

Answer 1

Hypo function: destruction or insuffienct stimualtino

Hyper function: excessive production of hormone or stimulation

Question 2

Location of adrenal glands

Answer 2

• 2 on top of kidneys; 3-5cm high, 2-3cm width and <1cm thick; Capsule: connective tissues + allows vessels to bind to gland; Highly vascularised; Richly innervated (sympathetic system)

Question 3

Function of Cortex:

Answer 3

• Synthesis + release of corticosteroids
• Cortisol and coricosteroids (glucocorticoids)
• Aldosterone
• Synthesis + release of androgen precursors

Question 4

Function of Medulla:

Answer 4

• Synthesis + release of catecholamines

* Adrenaline and noradrenaline

Question 5

Blood supply to glands

Answer 5

• Suprerenal arteries

1. Branching – in cortex and empty into the central vein of medulla
2. Direct – to medulla; supplying chromaffin cell with oxygenated blood

Question 6

Endocrinilogy of Catecholamines

Answer 6

• Adrenaline:Noradrenaline 4;1 (most chromatin cells are A – N cells or Nor)
• Circulaing levels: A 0.1/0.5nmol/L; N 1 – 2.5
• T1/2 (2-3mins)
• Cells lose all granules during fight or flight
• Released due to stressors
• Innervation by cholinergic preganglionic fibres of SNS (stimulation releases both A+N)
• Agonist = ACh (on nicotinic receptors), histamine and serotonin

Question 7

Biosynthesis

Answer 7

• L-Tyrosine > L-DOPA > Dopamine > Noradrenaline > Adrenaline
• Negative feedback and enzymatic

Question 8

Principals of catecholamines

Answer 8

• Not essential
• Intensify sympathetic responses
• Circulate bound to plasma albumin
• Inactivation by uptake and breakdown by enzymes (COMT AND MOA)

Question 9

General actions of catecholamines

Answer 9

•	Glycogenolysis
•	Lipolysis FFA ↑, glycerol ↑
•	Glucagon Release
•	↑ Metabolic Rate
	Insulin release

Question 10

Specific actions (8)

Answer 10

• Increase cardiac output
• Vasoconstriction
• Vasodilation
• Increase blood pressure
• Airway dilation
• CNS increase excitatbility and alertness
• Sweat production
• Contraction of radial and relaxation of ciliary muscles of eye = broadening and brighter fields of vision

Question 11

Pheochromocytomas

Answer 11

• Tumour of adrenal medulla = produce excess adrenaline (generally benign)
• Headaches; eecess sweating; racing heart; anxiety; tremor;
• Treatment: adrenalectomy