Kidney function 4 Flashcards
What controls the thirst reflex?
Osmoreceptors in the lateral preoptic area
How does GFR effect blood pressure?
Decreased GFR means less Na+ and water are filtered so blood volume increases, increasing blood pressure
Describe the baroreceptor response in the kidney
When afferent arterioles detect low blood pressure the sympathetic nervous system causes constriction of the AA and therefore reduces GFR, increasing blood pressure
What sensors are involved in controlling Na+ reabsorption in the kidney?
[NaCl] receptor in macula densa
pressure sensors in arterial tree
intrarenal baroreceptors
volume receptors in cardia atria and intrathoracic veins
What effectors exist to control Na+ reabsorption in the kidney?
Renal sympathetic nerves stimulate the release of renin, which increases Na+ absorption
Atrial natriuretic peptide decreases Na+ absorption
What juxtaglomerular cells contain renin + what stimulates its release?
Granular cells, released by sympathetic stimulation
How does [NaCl] in the macula densa effect renin release?
Increased NaCl in md inhibits renin release.
NaCl causes the production of adenosine which binds to A1 receptors to cause the release of Ca which causes contraction of the afferent arteriole, inhibits renin release
What causes renin release
decrease in macula densa nacl
decreased wall tension in afferent arteriole
What effects does angiotensin II have?
Stimulates PCT Na+ reabsorption by binding to AT1 receptors
Stimulates ADH release by binding to osmoreceptors
Stimulates aldosterone secretion, leads to increased Na+ reabsorption in DCT and CD
Where is aldosterone released from?
Zona glomerulosa of adrenal cortex
What does aldosterone do?
Increases Na+ reabsorption in DCT and CD
It also causes K+ secretion from principle cells of CD (released in response to hyperkalaemia)
Where are the natriuretic peptides released from?
Type A from the atrial myocardium
Type B from ventricular myocardium
What effects do natriuretic peptides do?
Inhibits Na+ reabsorption
Diuretic (inhibits ADH)
increases GFR (dilates afferent arterioles) + causes systemic vasodilation, so is hypotensive.
How does the macula densa affect renin release
Inhibits renin release
NaCl measured by MD
Increased NaCl stimulates adenosine, acting on the A1 receptors which lead to an increased Ca causing contraction of the afferent arteriole - less renin
How does ATII stimulate proximal tubule Na reabsorption
Binds to AT1 (Angiotensin II type 1) receptor
