Physio L6 Adrenal Cortex Flashcards
Aldosterone binds to which plasma protein?
Steroid-binding protein (SBP)
What are the target cells of Aldosterone?
Principal cells of DCT and CT
Name of aldosterone receptor? What is the final response?
Mineralocorticoid receptor (MR), synthesis of Aldosterone-induced proteins (increase Na+ reabsorption)
Effect of aldosterone on H+, which cells are involved?
Increase H+ excretion in intercalated cells of DCT & CT
What are the secondary effects of aldosterone?
1) Exocrine glands (mammary, gastric, sweat, salivary): increase Na+ reabsorption and excretion of K+
2) Small intestine: increase Na+ absorption, decrease K+ absorption.
What is the major regulator of Aldosterone secretion?
K+ concentration (1% increase increases Aldosterone by direct action on ZG)
What are the secondary regulators of aldosterone secretion?
1) Na+ concentration (hyponatremia—> secretion); direct effect on ZG
2) RAAS (stimulates secretion)
3) ECF volume
4) ACTH (mild stimulation)
What is Conn’s syndrome? What causes it?
Primary hyperaldosteronism: caused by adrenal adenoma or bilateral hyperplasia of ZG
Clinical presentation of Conn’s?
1) Reduced K+ (muscle weakness, ECG abnormalities, nephropathy)
2) Excessive loss of H+ —> metabolic alkalosis
3) Less ionized Ca2+ —> Tetany
4) No LL edema
Differentiate between primary and secondary hyperaldosteronism
Primary —> no LL edema due to “aldosterone escape phenomenon”
Secondary —> Edema present
Explain the Aldosterone escape phenomenon and its causes
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.
General features of cortisol
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)
What are the metabolic functions of Cortisol?
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
What are the actions of cortisol on body systems?
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)
What is the difference between cushing’s disease and syndrome?
Disease (secondary) is caused by Pituitary adenoma, while syndrome (primary) is caused by adenoma of ZF