The Adrenal Gland

Question 1

Are the kidneys situated in the intra or retroperitoneal space?

Answer 1

Retroperitoneal

Question 2

Into where does the right adrenal drain?

Answer 2

Right adrenal vein drains direct into the IVC

Question 3

Into where does the left adrenal drain?

Answer 3

The left adrenal vein drains into the left renal vein

Question 4

Which hormones are synthesised by the adrenal medulla?

Answer 4

Catecholamines - epinephrine (adrenaline), norepinephrine, dopamine

Question 5

What hormones are synthesised by the adrenal cortex?

Answer 5

3 classes of steroid hormone;

1. Mineralocorticoids e.g. ALDOSTERONE - involved in Na and K regulation
2. Glucocorticoids e.g. CORTISOL: involved in maintaining plasma glucose
3. Sex steroids e.g. testosterone

Question 6

Is it the adrenal medulla or cortex that is the true endocrine gland?

Answer 6

The cortex

Question 7

What are the three zones of the adrenal medulla, form innermost to outermost? What hormones are produced by each layer?

Answer 7

Zona glomerulosa - Aldosterone

Zona fasiculata - Glucocorticoids

Zona reticularis - Sex hormones

Adrenal Medulla - Catecholamines

Question 8

From what are al steroid hormones derived?

Answer 8

Cholesterol

Question 9

What are the tow main products of he adrenal cortex? In which two layers are they produced?

Answer 9

Cortisol - in the zona fasiculata

and aldosterone - in the zona glomerulosa

Question 10

Defects in which enzyme can often cause congenital adrenal hyperplasia? What is the result of this abnormality?

Answer 10

21-hydroxylase

Results in a deficiency pf aldosterone and cortisol and resulting dysfunction of salt and glucose balance

Question 11

How is adrenal cortex activity modulated?

Answer 11

Via a long feedback loop on the hypothalamus which regulates CRH release and consequently ACTH release

Question 12

Why would a 21-hydroxylase deficiency cause adrenal hyperplasia if it is causing hormones not to be produced?

Answer 12

The lack of 21-hydroxylase reduces the cortisol release and therefore removes this link from the negative feedback loop that is necessary for regulating the hypothalamus’ release of CRH. When this inhibition is not present, the hypothalamus increases CRH production which then causes increase ACTH release from the pituitary and activation of the adrenal cortex, causing hyperplasia even though the correct hormones are deficient

Question 13

What type of hormone is cortisol?

Answer 13

A glucocorticoid hormone (influences glucose metabolism)

Question 14

Is cortisol soluble in the plasma? Why?

Answer 14

No, it is a steroid hormone

Question 15

What is relevant about glucocorticoid receptors?

Answer 15

They are found in EVERY nucleated cell

Question 16

What is the effect of cortisol in terms of the cell function?

Answer 16

It either switches on or off the synthesis of new proteins

Question 17

Describe the classical pattern of cortisol release

Answer 17

There is a marked circadian rhythm, preceded by a similar release of ACTH. The cortisol burst persists longer than the ACTH because it has a much longer half life - peptide hormones not bound to plasma proteins and therefore easier to remove. It peaks 6-9am and is lowest at midnight.

Question 18

What is the result of a loss of cortisol?

Answer 18

An inability to deal with stress, particularly in terms of maintaining BG. Complete loss of cortisol results in death

Cortisol is crucial to protect the brain from hypoglycaemia

Question 19

What is the relationship between glucagon and cortisol?

Answer 19

Cortisol has a permissive effect on glucagon, which alone is not enough to deal with hypoglycaemic challenge and cannot protect the brain from damage

Question 20

What are the three glucocorticoid actions of cortisol?

Answer 20

Gluconeogenesis - enhances glucose production

Proteolysis - stimulates muscle breakdown = creates gluconeogenic substrates for the liver

Lipolysis - stimulates fat breakdown = FFA in the plasma to provide alternative food source so that BG can be preserved

Question 21

What are the four non-glucocorticoid actions of cortisol?

Answer 21

1. Negative effect on Ca2+ balance - less reabsorption in gut, more excretion at kidney
2. Impairment of mood and function - hypercortisolaemia = depression and impaired cognitive function
3. Permissive effect on norepinephrine - particularly vascular smooth muscle = HTN
4. Suppression of the immune system - reduces circulating lymphocyte count, antibody formation and inhibits inflammatory response

Question 22

What effect of high cortisol can be seen in the skin and muscle?

Answer 22

Cortisol will protect the brain from hypoglycaemia at all costs, and therefore its actions of lipolysis and proteolysis may result in muscle wastage and skin thinning and becoming more fragile

Question 23

What type of hormone is aldosterone? Where is it produced?

Answer 23

Mineralocorticoid

The zona glomerulosa of the adrenal cortex

Question 24

What is its main action?

Answer 24

On the distal tubule of the kidney determining the levels of minerals reabsorbed/excreted. It promotes Na in and K out

Question 25

What controls the release of aldosterone?

Answer 25

Secretion from the adrenal cortex is primarily controlled by a complex reflex pathway originating in the kidney - the renin-angiotensin-aldosterone system (RAAS)

Question 26

What is the effect of increased aldosterone?

Answer 26

Simulates Na and H20 retention and K depletion, resulting in increased BP

Question 27

What is the result of decreased aldosterone?

Answer 27

Leads to Na and H20 loss, and K retention, which = decreased BP

Question 28

What is a significant disease which is associated with hypersecretion of cortisol? How else can hypercortisolism be caused?

Answer 28

Cushing’s syndrome/disease

Too much cortisol administered therapeutically

Question 29

What significant disease is associated with hypo secretion of cortisol?

Answer 29

Addison’s disease - hypo secretion of all adrenal steroid hormones due to autoimmune destruction of the adrenal cortex

Question 30

Describe the adrenal medulla

Answer 30

A modified sympathetic ganglion that is not true endocrine tissue, it is similar to the posterior pituitary in having a neuroendocrine function

Question 31

What is pheochromocytoma?

Answer 31

A rare endocrine tumour found in the adrenal medulla with results in excess catecholamines = increased HR , increased CO and increased BP

Responds well to surgery