Adrenal cortex

Question 1

outline the anatomy and function of the adrenal cortex

Answer 1

inner adrenal medulla secretes catecholamines, concerned with stress response,sodium + glucose homeostasis.
outer adrenal cortex secretes adrenal sex steroids -progesterone, testosterone + oestrogens.

Question 2

what are the functions of the three distinct layers of the adrenal cortex?

Answer 2

Outer zona glomerulosa (mineralocorticoid e.g. aldosterone synthesis).
Middle zona fasciculata (glucocorticoids e.g. hydrocortisone/cortisol).
Innermost zona reticularis (produces androgen precursors).

Question 3

what are the major secretions of the adrenal cortex and what are their functions?

Answer 3

Glucocorticoids (e.g. hydrocortisone/cortisol)affect carbohydrate and protein metabolism and regulate host defence mechanisms.
Mineralocorticoids (e.g. aldosterone) regulate water and electrolyte balance.

Question 4

how does mineralocorticoid sensitive tissues (e.g. kidney) prevent responding to hydrocortisone?

Answer 4

11-β-hydroxysteroid dehydrogenase converts hydrocortisone to the inactive metabolite cortisone

Question 5

what are the effects of glucocorticoids on the cardiovascular system?

Answer 5

reduced vasodilation and decreased fluid exudation

Question 6

what are the negative effects of glucocorticoids on the musculoskeletal system?

Answer 6

decreased osteoblast and increased osteoclast activity

Question 7

what is the effect of glucocorticoids on inflammation and immunity?

Answer 7

anti-inflammatory. allows infection to continue whilst masked.

Question 8

how are glucocorticoids synthesised and released?

Answer 8

synthesised under the influence of ACTH from anterior pituitary, released in a pulsatile fashion. ACTH secretion is regulated by CRH release from hypothalamus and by ADH release from posterior pituitary. high glucocorticoid concentration in blood prevents release of ACTH and CRH.

Question 9

how can hyperglycaemia arise due to the metabolic actions of glucocorticoids?

Answer 9

carbohydrates: decreased uptake and utilisation of glucose accompanied by increased gluconeogenesis

Question 10

how can muscle wastage arise due to the metabolic actions of glucocorticoids?

Answer 10

increased catabolism; reduced anabolism

Question 11

When are the effects of cortisol rapid?

Answer 11

feedback inhibition of ACTH secretion

Question 12

Cortisol opposes which hormone?

Answer 12

Insulin. antagonises effect of insulin on cellular uptake of glucose. stimulates glycogenolysis and hepatic gluconeogenesis.

Question 13

How does cortisol effect lipolysis?

Answer 13

stimulates lipolysis and mobilisation of fatty acids, partially by potentiating the effects of growth hormone and catecholamines.

Question 14

How does cortisol effect the periphery?

Answer 14

inhibits aminoacid uptake and protein synthesis,resulting in a net loss of skeletalprotein.

Question 15

What leads to a rapid secretion of ACTH and corticosteroids?

Answer 15

psychological and physiological stress e.g. trauma, infection, hypoglycaemia

Question 16

What are the unwanted effects of glucocorticoids?

Answer 16

suppression of response to infection or injury, Cushing’s syndrome, osteoporosis, hyperglycaemia can precipitate diabetes, muscle wasting and weakness, inhibition of growth in children.

Question 17

What are the causes of Cushing’s syndrome?

Answer 17

excessive exposure to glucocorticoids: ACTH secreting tumour or prolonged administration of glucocorticoid drugs (iatrogenic).

Question 18

What are the most adverse effects of excess glucocorticoids?

Answer 18

suppression of HPA axis and ACTH secretion leading to atrophy of the adrenal cortex.

Question 19

What is the most important role of glucocorticoids?

Answer 19

responding to stress. at times of prolonged stress glucocorticoidsmaintain enhanced supply of glucosebut they also suppress theinflammatory response.

Question 20

How does the adrenocortical stress response influence the inflammatory response?

Answer 20

removes pain and decreases the immobilisation induced by oedema.
steroid-induced sedation causes a lower perceived severity of the situation.
so individual can perform despite presence of injury or infection.

Question 21

What is Addison’s disease and what is it characterised by?

Answer 21

low cortisol production.

muscular weakness, low blood pressure, depression, anorexia, loss of weight and hypoglycaemia.

Question 22

What are the causes of Addison’s disease?

Answer 22

stopping steroid therapy abruptly (Addisonian crisis), autoimmune, or destruction of the gland by chronic inflammatory conditions e.g. tuberculosis.

Question 23

What are the pharmacological uses of glucocorticoids?

Answer 23

replacement therapy and for their immunosuppressive or anti-inflammatory effects e.g. in arthritis, asthma or allergies, or for the treatment of proliferative conditions e.g. leukaemia. ​

Question 24

What directly stimulates and inhibits the secretion of aldosterone?

Answer 24

trauma,anxiety, hyperkalaemia andhyponatraemia.

inhibited byANP

Question 25

What is the action of aldosterone?

Answer 25

sodium reabsorption in distal tubule of kidney. influences plasma sodium concentration, which in turn influences water reabsorption in collecting duct via an effect on ADH secretion.

Question 26

What are mineralocorticoids only used for?

Answer 26

replacement therapy

Question 27

What is the use, action and adverse effects of hydrocortisone?

Answer 27

hormone replacement therapy as anti-inflammatory agents and immunosuppressants.
acts via specific intracellular glucocorticoid receptors to influence gene expression.
hyperglycaemia, osteoporosis, Cushing’s syndrome