8. Adrenal gland and its hormones

Question 1

What are the 2 sections of the adrenal glands?

Answer 1

1. Inner - medulla
2. Outer - cortex

Question 2

What type of hormones does the medulla secrete?

Answer 2

Secretes catecholamines e.g. adrenaline, noradrenaline

Question 3

What type of hormones does the cortex secrete?

Answer 3

Secretes adrenocortical steroid hormones

Question 4

Describe the structure of the cortex of the adrenal glands.

Answer 4

1. Zona glomerulosa
2. Zona fasciculata
3. Zona reticularis

Question 5

State the hormones made by the different sections of the cortex.

Answer 5

1. Zona glomerulosa -> Mineralcorticoids e.g. Aldosterone
2. Zona fasciulata -> Glucocorticoids e.g. Cortisol, Cortisone
3. Zona reticularis -> Androgens (sex hormone precursors)

GFR – Makes Good Sex

Question 6

Mnemonic to remember the order of adrenal cortex sections and their respective released hormones.

Answer 6

GFR – Makes Good Sex

Glomerulosa, Fasciculata, Reticularis -> Mineralcorticoids, Glucocorticoids, Sex hormone precursors (androgens)

Question 7

What are adrenalcortical hormones synthesised from?

Answer 7

Cholesterol

Question 8

Describe the initial conversion of cholesterol.

Answer 8

Cholesterol converted to Pregnenolone via enzyme, Cholesterol desmolase:

Cholesterol
↓ Enzyme, cholesterol desmolase
Pregnenolone

Cholesterol desmolase - stimulated by ACTH

Question 9

What stimulates cholesterol desmolase secretion?

Answer 9

Cholesterol desmolase - stimulated by ACTH

Question 10

Describe aldosterone synthesis in the zona glomerulosa.

Answer 10

Question 11

What stimulates aldosterone synthase?

Answer 11

Angiotensin II

Question 12

State 3 functions of aldosterone.

Answer 12

1. Regulates extracellular fluid volume
2. Potassium homeostasis
3. Increase renal water + sodium reabsorption via RAAS

Question 13

Describe cortisol synthesis in the zona fasciculata.

Answer 13

Question 14

State 5 functions of cortisol.

Answer 14

1. Stress response
2. Metabolic effects
3. Immunosuppressive effects
4. Anti-inflammatory effects
5. Vascular effects

Question 15

Describe the metabolic effects of cortisol.

Answer 15

1. ↑ blood glucose by ↑ hepatic glycogenolysis
   (‘diabetogenic hormone’)
2. ↑ lipolysis
3. ↑ protein catabolism
4. ↓ cellular insulin sensitivity

Question 16

Describe the immune effects of cortisol.

Answer 16

↓↓ intensity of immune + inflammatory responses:

1. ↓ production of Arachidonic Acid metabolites e.g. prostaglandin, thromboxane, leukotrienes
2. ↓ production of interleukins,, interferons + TNF
3. ↓ T-cell proliferation
4. ↓ neutrophil phagocytosis

Question 17

Describe the vascular effects of cortisol.

Answer 17

Involved in normal vascular blood pressure maintenance.

Supports vascular smooth muscle responsiveness to catecholamine vasoconstrictive effects.

Question 18

Give 3 functions of cortisol in response to stress.

Answer 18

1. Mobilises energy sources -> lipolysis, gluconeogenesis and protein break down.
2. Vasoconstriction.
3. Suppresses inflammatory and immune repsonses.
4. Inhibits non-essential functions e.g. growth and reproduction.

Question 19

What is important about the androgens in the adrenal cortex for females?

Answer 19

Only source of androgens in biologically-female individuals

Question 20

Describe the mechanism of ACTH.

Answer 20

Hypothalamus -> CRH -> AP -> ACTH -> adrenal cortex (zona fasciculata) -> glucocorticoid synthesis e.g. cortisol.

Cortisol has a negative feedback effect on the hypothalamus and the anterior pituitary.

Question 21

What is the affect of cortisol on insulin and glucagon?

Answer 21

Cortisol inhibits insulin and activates glucagon.

Question 22

Describe the pattern of cortisol release.

Answer 22

Normal pulsatile secretion.
Approx. 10 surges in diurnal (daily) pattern.
Highest concentration in the morning; lowest in the evening.

Question 23

What regulates the secretion of ACTH and cortisol?

Answer 23

The suprachiasmatic nucleus (SCN) in the hypothalamus

Question 24

State 2 ways cortisol secretion is stimulated.

Answer 24

1. Stress
   e.g. infection, trauma, F/F response, psychological stressors
2. Negative feedback loop