Jun 10, 2025
Q17. Normal range of urine osmolality (mosm/l):
Q18. The prime driving force for counter current multiplier system is:
Q19. Maximum osmotic gradient is found in:
Q20. Which of the following is not a component of the counter current multiplier mechanism?
Ans. The ratio between O2 consumption and supply is known as the oxygen extraction ratio. In the case of cortical nephron, oxygen consumption and supply both are higher but O2 supply is
more than that of oxygen consumption.
Ans. It is present in juxta-medullary nephrons and consists of two parts: countercurrent multiplier and
Exchanger. Countercurrent multiplication occurs at the level of the loop of Henle of juxta-medullary nephrons. Counter-current exchange occurs at the level of the peritubular capillary loop of the juxtamedullary loop. It is also called the vasa recta.
Ans. There are 2 mechanisms
Myogenic mechanism: It is mediated through calcium. It occurs at the level of smooth muscles of afferent arterioles. ↑BP causes the individual smooth muscle present on afferent arteriole to stretch. Smooth muscle membrane contains stretch-sensitive Ca++ channels that open because of mechanical stretch. When calcium reaches the cytoplasm of cells, there is contraction of smooth muscles leading to constriction of afferent arterioles.
Ans. The site of the mechanism of action is TAL. Because it is the TAL segment of the Nephron which has the NKCC transporter.
Ans. Macula densa cell is a part of the TAL segment of the Nephron.
Ans. The universal transporter is sodium and potassium ATPase on the cell's basolateral membrane.
Ans. TAL through passive paracellular reabsorption.
Ans. PCT
Ans. Paracellular pathway.
Ans. TRPM 6/7 channel that uses a transcellular route.
Ans. Source is secretion. It is important to remember that potassium is the only electrolyte that can be secreted as well as reabsorbed into the body. The portion from which it is getting secreted is the latter part of the DCT and the cortical collecting duct. The same part can also be reabsorbed.
Ans. 50-60% of tonicity is contributed by sodium chloride and urea contributes 40-50% of tonicity.
Ans. The maximum tonicity that can develop upon medullary interstitium taken in general is 1200-1400 mOsm/L. Therefore, it can be assumed that sodium chloride provides 600 mOsm and urea gives another 600 mOsm. Sodium provides 300 mOsm and chloride gives another 300 mOsm. Hence, urea is the single most important substance responsible for medullary hypertonicity.
A. NaCl
B. Urea
Ans. As NaCl contributes 50-60% tonicity, it is the most important substance for medullary hypertonicity.
A. Na
B. Cl
C. Urea
Ans. Urea is the most important substance for medullary hypertonicity.
Ans. ATS
A. 50-1400
B. 100-1400
C. 200-1000
D. 300-1200
Ans. 50-1400
A. Reabsorption of Na+ in thick ascending limb
B. Action of ADH via aquaporin channels
C. Urea recycling
D. Medullary hyperosmolarity
Ans. Reabsorption of Na+ in thick ascending limb
A. Outer medulla
B. Inner medulla
C. Outer cortex
D. Inner cortex
Ans. Inner medulla
A. Thick ascending loop of Henle
B. Collecting duct
C. Vasa recta
D. Thin descending loop of Henle
Ans. Vasa recta
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