A substance is present in concentration of 2 mg% in the afferent arteriole and zero mg% in the efferent. Which of the following statement is true about this substance?
A. It is freely filtered at the glomerulus
B. Secreted in cortical nephron
C. Absorbed in PCT
D. Impermeable in loop of Henle
Ans. A. It is freely filtered at the
glomerulus.
Explanation: Afferent arteriole leads to the glomerulus; at the glomerulus the filtration of substances occurs. The blood then leaves the glomerulus via efferent arteriole. If the substance was present in the afferent arteriole in some concentration, and is not present in the efferent arteriole, it means it has been freely filtered at the glomerulus. It is completely removed from the blood by glomerular filtration.
If the same concentrations are applied to renal artery and renal vein respectively, it means the substance is completely removed from blood in a single pass. That is, it enters the kidney, filtered at the glomerulus and secreted by the tubules. It is completely removed by these two processes in a single pass. , so that it is not present at all in the renal vein.
Explanation: Afferent arteriole leads to the glomerulus; at the glomerulus the filtration of substances occurs. The blood then leaves the glomerulus via efferent arteriole. If the substance was present in the afferent arteriole in some concentration, and is not present in the efferent arteriole, it means it has been freely filtered at the glomerulus. It is completely removed from the blood by glomerular filtration.
If the same concentrations are applied to renal artery and renal vein respectively, it means the substance is completely removed from blood in a single pass. That is, it enters the kidney, filtered at the glomerulus and secreted by the tubules. It is completely removed by these two processes in a single pass. , so that it is not present at all in the renal vein.
