Lecture 7-BP And The Kidney Flashcards
Where is renin released from?
Granular cells of juxtaglomerular apparatus
What stimulates renin release?
- decreased NaCl detected by macula densa
- reduced perfusion pressure in kidney
- sympathetic stimulation to JGA (beta 1 receptors)
What are the actions of Ang II?
- increased sympathetic stimulation
- increased tubular NaCl reabsorption, water retention and K+ excretion
- increased aldosterone release
- increased arteriolar vasoconstriction
- increased ADH secretion
Which arteriole is more constricted as a result of AngII on the kidney?
Efferent
What is the action of aldosterone on the kidney?
Acts on principle cells of CD to stimulate Na+ and water reabsorption by activating ENaC and increasing basolateral extrusion of Na+ via Na/K ATPase
What effect does sympathetic stimulation have on the kidney?
Activates apical NHE and basolateral Na/K ATPase in PCT and stimulates renin release from JGA
What effect do prostaglandins have on the kidney?
Vasodilation of afferent arteriole and enhances renin release when released locally
What effect do RAAS and prostaglandins have together?
- systemic vasoconstriction
- Ang II: vasoconstriction of efferent and prostaglandins: vasodilation of afferent
What effect does ADH have on the kidney?
Forms concentrated urine by retaining water in the distal nephron (via AQP 2)
What is the effect of ANP on the kidney?
Causes vasodilation systemically and of the afferent arteriole to increase GFR
Inhibits Na+ reabsorption in CD -> natriuresis
How does stenosis in the kidney cause hypertension?
Stenosis -> increased renin -> increased AngII -> vasoconstriction -> hypertension OR
Stenosis -> increased renin -> increased AngII -> increased aldosterone -> increased blood volume -> hypertension
What is the difference between unilateral and bilateral renal artery stenosis?
- unilateral: no fluid overload because the other kidney gets rid of fluid
- bilateral: fluid overload
How can primary hyperaldosteronism cause hypertension?
Increased aldosterone -> NaCl and water reabsorption and K+ secretion -> hypertension
How can CKD cause hypertension?
Can’t excrete excess salt and water due to decreased GFR -> hypertension
