What is true? (AIIMS NOV 2008)
|A||Clearance of a substance which is freely filtered and actively secreted is greater than GFR|
|B||Clearance of a substance which is filtered and|
|C||reabsorbed is greater than the clearance of inulin|
|D||Descending loop of Henle has hypotonic fluid|
|E||Descending loop of Henle is permeable to solutes|
I. The explanation is based on the basic definition and the concept of clearance.
II. The clearance of a substance which is freely filtered and neither secreted nor reabsorbed (e.g. inulin clearance) gives the value of GFR.
III. Any substance which has a clearance greater than that of inulin must be getting secreted in addition to being freely filtered.
IV. One of the most important aspects of counter-current multiplier system is the differential permeability characteristic of descending thin segment (DTS) and the ascending thin segment of the loop of Henle (ATS):
a. DTS : is permeable to water but not sodium
b. ATS : is permeable to sodium but not water
V. Due to this, the tubular fluid in the descending loop gets hypertonic whereas in the ascending limb, the tubular fluid becomes dilute.