Question

Which one of the following statements is not correct?

	A.	Over a week-long period, if a healthy person were to ingest 35 g of NaCl, the total amount of NaCl excreted in the urine would be less than 35 g.
	B.	In the proximal tubule, large amounts of Na+ and water are reabsorbed but the concentration of Na+ in the proximal tubular fluid does not change.
	C.	A drug that inhibits active NaCl reabsorption in the ascending limb of the loop of Henle will likely increase the volume of urine production.
	D.	If a substance is present in the urine, that substance must necessarily be filtered out of the glomerulus into Bowman’s capsule.
	E.	Fluid in the proximal tubule does not normally contain protein.

Answer 1

Option D-

For a substance to be present in the urine it is not necessary that the substance must be filtered out of the Glomerulus in to Bowmans Capsule.This happens because some Substances are secreated into the Renal tubules after the process of filtration in the glomerulus.

Secretion , which occurs in the proximal tubule section of the nephron , is responsible for the transport of certain molecules out of the blood and into the urine. Secreted substances include potassium ions, hydrogen ions, creatinine, ions, and other types of waste products, such as drugs. Tubular secretion is the transfer of materials from peritubular capillaries to the renal tubular lumen and occurs mainly by active transport and passive diffusion.

All other options are true-

a)Amount of Nacl excreated will be less than ingested

b)In the PCT 65% of water, 100% of glucose, 100% amino acids, 65% of potassium, 65% chloride and 67% of sodium is reabsorbed.Hence concentration of Na almost remain Same.

c)if Nacl Reabsorption is inhibited---more nacl in the fluid---draws more water into it---increased urine ouput

E)Under physiological conditions, the large molecular weight proteins and blood cells do not pass through the capillary wall and hence do not appear in the luminal fluid.

(A Small amount of albumin may be filtered from the Glomerulus,that is usually reabsorbed from the PCT)