CSR Renal Physiology & Pathophysiology 2

Question 1

Which segment of the nephron is primarily responsible for the reabsorption of approximately 65% of filtered sodium?

Accepted Answer

Proximal convoluted tubule

Answer

The proximal convoluted tubule reabsorbs roughly 65% of filtered sodium via sodium-hydrogen exchangers and sodium-coupled transporters, making it the nephron's primary sodium reabsorption site.

Question 2

In chronic kidney disease, decreased production of which hormone by the peritubular cells leads to anemia?

Accepted Answer

Erythropoietin

Answer

Erythropoietin (EPO) is produced by peritubular interstitial cells in the renal cortex. CKD leads to fibrosis and loss of these cells, reducing EPO production and causing normocytic normochromic anemia.

Question 3

The renin-angiotensin-aldosterone system (RAAS) is activated when renal perfusion pressure falls. Which renal cells are responsible for renin secretion?

Accepted Answer

Juxtaglomerular cells

Answer

Juxtaglomerular (JG) cells in the afferent arteriole wall are specialized smooth muscle cells that synthesize, store, and secrete renin in response to reduced perfusion pressure.

Question 4

Which pathophysiological mechanism primarily explains the metabolic acidosis commonly seen in advanced CKD (GFR < 30 mL/min)?

Accepted Answer

Reduced ammoniagenesis and net acid excretion by the failing kidney

Answer

Advanced CKD impairs ammoniagenesis in the proximal tubule and reduces functioning nephrons, resulting in decreased net acid excretion and retention of fixed acids, causing metabolic acidosis.

Question 5

In nephrotic syndrome, massive proteinuria leads to hypoalbuminemia and edema. What is the primary mechanism of edema formation?

Accepted Answer

Reduced plasma oncotic pressure leading to fluid shift into interstitium

Answer

Loss of albumin reduces plasma oncotic pressure (colloid osmotic pressure), allowing hydrostatic pressure to push fluid into the interstitial space, causing edema.

(CSR) Board Certified Specialist in Renal Nutrition Practice Test

(CSR) Board Certified Specialist in Renal Nutrition Practice Test

CSR Renal Physiology & Pathophysiology 2