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Physiology

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Kidney

Question
20 out of 26
 

ANP acts at which site?



A Collecting duct
B Ascending Loop

C Descending Loop
D PCT

Ans. A Collecting duct

ANP binds to a specific set of receptors - ANP receptors. Receptor-agonist binding causes a reduction in blood volume and therefore a reduction in cardiac output and systemic blood pressure.Lipolysis is increased and renal sodium reabsorption is decreased. The overall effect of ANP on the body is to counter increases in blood pressure and volume caused by the renin-angiotensin system.

Renal

a. Dilates the afferent glomerular arteriole, constricts the efferent glomerular arteriole, and relaxes the mesangial cells. This increases pressure in the glomerular capillaries, thus increasing the rate (GFR), resulting in greater excretion of sodium and water.

b. Increases blood flow through the vasa recta which will wash the solutes (NaCl and urea) out of the medullary interstitium.[8] The lower osmolarity of the medullary interstitium leads to less reabsorption of tubular fluid and increased excretion.

c. Decreases sodium reabsorption in the distal convoluted tubule (interaction with NCC) and cortical collecting duct of the nephron via guanosine 3',5'-cyclic monophosphate (cGMP) dependent phosphorylation of ENaC

d. Inhibits renin secretion, thereby inhibiting the renin-angiotensin-aldosterone system.

e. Reduces aldosterone secretion by the adrenal cortex.

Vascular

Relaxes vascular smooth muscle in arterioles and venules by:

a. Membrane Receptor-mediated elevation of vascular smooth muscle cGMP

b. Inhibition of the effects of catecholamines

Kidney Flashcard List

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