Urology>>>>>Renal Pathophysiology
Question 1#

Which of the following is CORRECT regarding the nephron?

A. The glomerulus is about 20 μm in diameter and is formed by the invagination of a tuft of capillaries into the dilated, open end of the nephron (Bowman’s capsule)
B. Functionally, the glomerular basement membrane permits the free passage of neutral substances upto 4 nm in diameter and totally excludes those with diameters greater than 8 nm
C. In the distal convoluted tubule, while the predominant principle cells (P) are involved in acid secretion and HCO3 − transport, the intercalated cells (I) are associated with Na+ reabsorption and vasopressin-stimulated water reabsorption
D. The renin-secreting juxtaglomerular cells are situated in that part of the thick ascending limb of the loop of Henle, which traverses close to the afferent arteriole from which the tubule arose
E. In a resting adult, the kidneys receive about 450 mL of blood per minute

Correct Answer is B

Comment:

Answer B

The glomerulus, which is about 200 μm in diameter, is formed by the invagination of a tuft of capillaries into the dilated, blind end of the nephron. In the distal convoluted tubule, while the predominant principle cells (P) are involved in Na+ reabsorption and vasopressin-stimulated water reabsorption, the intercalated cells (I) are associated with acid secretion and HCO3 − transport. It is the wall of the afferent arteriole that contains renin-secreting juxtaglomerular cells. At this point the wall of the tubular epithelium is modified histologically to become the macula densa. The juxtaglomerular cells, the macula densa and the lacis cells near them are collectively known as juxtaglomerular apparatus. The kidney receives 25% of cardiac output.