Physio L6 Adrenal Cortex

Question 1

Aldosterone binds to which plasma protein?

Answer 1

Steroid-binding protein (SBP)

Question 2

What are the target cells of Aldosterone?

Answer 2

Principal cells of DCT and CT

Question 3

Name of aldosterone receptor? What is the final response?

Answer 3

Mineralocorticoid receptor (MR), synthesis of Aldosterone-induced proteins (increase Na+ reabsorption)

Question 4

Effect of aldosterone on H+, which cells are involved?

Answer 4

Increase H+ excretion in intercalated cells of DCT & CT

Question 5

What are the secondary effects of aldosterone?

Answer 5

1) Exocrine glands (mammary, gastric, sweat, salivary): increase Na+ reabsorption and excretion of K+
2) Small intestine: increase Na+ absorption, decrease K+ absorption.

Question 6

What is the major regulator of Aldosterone secretion?

Answer 6

K+ concentration (1% increase increases Aldosterone by direct action on ZG)

Question 7

What are the secondary regulators of aldosterone secretion?

Answer 7

1) Na+ concentration (hyponatremia—> secretion); direct effect on ZG
2) RAAS (stimulates secretion)
3) ECF volume
4) ACTH (mild stimulation)

Question 8

What is Conn’s syndrome? What causes it?

Answer 8

Primary hyperaldosteronism: caused by adrenal adenoma or bilateral hyperplasia of ZG

Question 9

Clinical presentation of Conn’s?

Answer 9

1) Reduced K+ (muscle weakness, ECG abnormalities, nephropathy)
2) Excessive loss of H+ —> metabolic alkalosis
3) Less ionized Ca2+ —> Tetany
4) No LL edema

Question 10

Differentiate between primary and secondary hyperaldosteronism

Answer 10

Primary —> no LL edema due to “aldosterone escape phenomenon”
Secondary —> Edema present

Question 11

Explain the Aldosterone escape phenomenon and its causes

Answer 11

It is the escape of kidney tubules from Na+ retention in-spite of excess aldosterone.
It is due to expansion of ECF volume leading to release of ANP which will cause loss of Na+ and H2O while also inhibiting RAAS.

Question 12

General features of cortisol

Answer 12

1) only 10% is free (80% binds SBP & 10% binds Albumin)
2) Aligned with circadian rhythm
3) Its essential for life (since its part of cortex, only medulla is non-essential)

Question 13

What are the metabolic functions of Cortisol?

Answer 13

1) CHO: hyperglycemic (Increased liver gluconeogensis, decreased insulin sensitivity, inhibit glucose uptake)
2) Lipids: lipolytic (increase FFA)
3) Proteins: Catabolic except in Liver anabolic
4) Minerals: increase Na+ & H2O retention

Question 14

What are the actions of cortisol on body systems?

Answer 14

1) CNS: Decreases REM sleep (insomina), causes excitability
2) CVS: Permissive effect on catecholamines (vasoconstriction—>increases BP)
3) Renal: Na+ & H2O retention, however it inhibits Aldosterone (hence can be used to for H2O removal)
4) GIT: increase HCL secretion (Peptic Ulcer)

Question 15

What is the difference between cushing’s disease and syndrome?

Answer 15

Disease (secondary) is caused by Pituitary adenoma, while syndrome (primary) is caused by adenoma of ZF

Question 16

Define Addison’s disease and its cause

Answer 16

It is the hypofunction of all adrenal cortex hormones caused by bilateral destruction by Autoimmune condition, tumor or TB

Question 17

What is a characteristic presentation other than the effects of hormone deficiency occurs on Addison’s?

Answer 17

Dark skin pigmentation due to increase ACTH (which has MSH like action)