Adrenal gland

Question 1

From which embryological tissues are the adrenal cortex and medulla derived?

Answer 1

Cortex: mesoderm

Medulla: neural crest

Question 2

How many weeks in to gestation until adrenal gland can be distinguished as a discrete organ?

Answer 2

8 weeks in

Question 3

What are the fetal and definitive zones relating to the adrenal cortex?

Answer 3

Fetal zone is the time frame between 2 months into gestation and birth where the adrenal cortex grows to a maximum weight. The zona reticularis is particularly prominent as the androgens it secretes are aromatized to oestrogens in the placenta, which are vital for a successful pregnancy

Definitive zone is just the time frame during which the adult cortex develops, after birth until adulthood

Question 4

Microscopic structure of adrenal medulla

Answer 4

Chromaffin cells packed with granules (containing catecholamines)

Question 5

Zones of adrenal cortex

Answer 5

Outer - zona glomerulosa (aldosterone)
Middle - zona fasciculata (cortisol)
Inner - zona reticularis (androgens)

Question 6

Blood supply and drainage of adrenal gland

Answer 6

Receives branches from inferior phrenic artery, renal arteries and aorta

These collect at an arterial plexus beneath the adrenal capsule and enter a sinusoidal capillary system that richly perfuses the whole organ, from cortex to medulla

All blood drains into a central adrenal vein (one per gland) found in the medulla

Left adrenal vein drains into the left renal vein and the right adrenal vein drains into the inferior vena cava

Question 7

Innervation of adrenal gland

Answer 7

Mostly to medulla, and stimulatory

Thoracic preganglionic sympathetic nerves (bypass sympathetic chain) which release ACh - medulla has nAChRs

Question 8

catecholamines receptors and actions image

Answer 8

Notability || Revision || Anatomy || Catecholamines

Question 9

What group of hormones are synthesised by the adrenal cortex? From which precursor molecule are they all synthesised?

Answer 9

Various steroid hormones, all synthesised from cholesterol

Corticosteroids such as:

• Glucocorticoids (cortisol)
• Mineralocorticoids (aldosterone)

Some sex steroids (adrenal androgens)

Question 10

By what mechanism do these hormones act?

Answer 10

Nuclear receptors (hormone response elements within gene promoters) - binding affects gene transcription

Question 11

How are cortex hormones transported in the plasma?

Answer 11

Cortisol - cortisol-binding globulin (high affinity) and albumin (low affinity)
Aldosterone and androgens - only albumin (low affinity)

Question 12

Define stress

Answer 12

A stimulus that threatens to disturb homeostasis

Question 13

Overarching action of cortisol

Answer 13

Protection of body against stress, primarily by preserving glucose for the brain

Question 14

Affects of cortisol on metabolism

Answer 14

Carbs - stimulates gluconeogenesis, opposing insulin
Fats - stimulates lipolysis and ketogenesis to make more ketones for the brain
Proteins - stimulates gluconeogenesis

Question 15

What does adrenal insufficiency lead to?

Answer 15

Addison’s disease

Question 16

What does adrenal excess lead to?

Answer 16

Cushing’s disease