During selective reabsorption in the mammalian nephron, glucose and amino acids are completely reabsorbed back into the bloodstream from the glomerular filtrate. In which specific region of the nephron does this process primarily take place, and what structural feature enables it?
- Proximal convoluted tubule, supported by a dense brush border of microvilli and abundant mitochondriaAnswer
- BBowman's capsule, supported by podocytes forming specialized filtration slits
- CDescending limb of the Loop of Henle, supported by thick impermeable chitinous walls
- DDistal convoluted tubule, supported by ciliated epithelial cells that sweep filtrate along
Answer
Proximal convoluted tubule, supported by a dense brush border of microvilli and abundant mitochondria
Selective reabsorption of glucose, amino acids, and essential ions occurs predominantly in the proximal convoluted tubule (PCT). The epithelial cells lining the PCT are structurally adapted for intensive active transport: they possess a microvillar brush border that vastly increases the absorptive surface area and contain numerous mitochondria to generate the ATP required for active carrier-mediated transport back into the peritubular capillaries.
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Key Concept
Nephron Physiology and Selective Reabsorption