Question

There can be more than one correct answer!

12. Renin

A. increases Na+ reabsorption

B. is released by JG cells when macula densa cells detect slower

flow of NaCL thorough the distal convoluted tubule

C. is released by JG cells when the pressure in the afferent

arteriole increases

D. stimulates the release of aldosterone from the adrenal cortex

17. Reabsorption of H2O in the medullary collecting ducts is by

A. active transport B. simple diffusion C. facilitated diffusion D. endocytosis

32. Emulsification of fat globules involves both mechanical

disruption of globules into fat droplets and then the prevention of those

droplets from reforming into globules with the assistance of

A. bile salts

B. micelles

C. phospholipids

D. chylomicrons

21. Why does the renal clearance of creatinine slightly

overestimate the GFR?

A. no creatinine is reabsorbed

B. a small amount of creatinine is reabsorbed

C. no creatinine is secreted

D. a small amount of creatinine is secreted

E. more creatinine is filtered than other substances

Answer 1

12	A. increases Na+ reabsorption	Angiotensin (associated with renin) causes release of aldosterone which stimulate the activity of distal tubular cells and collecting tubes ok kidney and promote sodium reabsorption.
B. is released by JG cells when macula densa cells detect slower flow of NaCL thorough the distal convoluted tubule	The decrease in the load of sodium measured by macula densa promotes secretion of renin.
D. stimulates the release of aldosterone from the adrenal cortex	Renin cleaves a protein angiotensinogen and convert it into into angiotensin I. Angiotensin I is further transformed to angiotensin II, that promotes release of aldosterone from the adrenal cortex of adrenal glands.
17	B. Simple diffusion	In the medullary duct the reabsorption of urea occurs at thick ascending limb (impermeable to water). In the interstitum urea acts as osmol an permits water reabsorption (by diffusion).
32	A. Bile salts	Fats are emulsified by bile salts in the process of digestion of food. The digestion is promoted by lipase. Bile salts have detergent like properties that emulsify the fat globules and promote rapid fat digestion (lipolysis).
21	D. a small amount of creatinine is secreted	Inulin is filtered freely through glomerulus. It is not secreted or reabsorbed. As some creatine is secreted into renal tubules, the creatinine clearance overestimates glomerular filtration rate.