ECOLOGY
EXCRETORY PRODUCTS AND THEIR ELIMINATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Ions like Na+ and Cl-
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Nutrients like glucose and amino acids
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Substances like drug metabolites and waste
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Water
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Detailed explanation-1: -Water reabsorption takes place in the cortical collecting duct (CCD) cells, induced by the peptide hormone vasopressin. An increase in 3’5’-cyclic adenosine monophosphate (cAMP) levels in these cells leads to an increasing permeability of the CCD apical membrane to water.
Detailed explanation-2: -Glucose, amino acids, NaCl and other essential salts are reabsorbed in the second step of urine formation i.e Tubular Reabsorption. These essential substances are filtered from blood in the first step called glomerular filtration and are reabsorbed as they are vital for body function.
Detailed explanation-3: -The bulk of filtered water is reabsorbed in the proximal tubule through the activity of AQP1. The process is regulated, however, primarily through the interaction of vasopressin with principal cells of the collecting duct and its effects on AQP2 and AQP3. Changes in AQP2 or the vasopressin V2 receptor lead to disease.
Detailed explanation-4: -As more sodium is reabsorbed by the cell, even more water travels into the interstitium. At times of extreme dehydration, the collecting duct can absorb about 20% of the total amount of water found in the filtrate from the collecting duct.