PCT Reabsorption of Electrolytes & Water — NEET Biology
✅ Asked in NEET 2016Proximal Convoluted Tubule (PCT): PCT is lined by simple cuboidal brush border epithelium which increases the surface area for reabsorption. Nearly all of the essential nutrients, and 70-80 per cent of electrolytes and water are reabsorbed by this segment. PCT also helps to maintain the pH and ionic balance of the body fluids by selective secretion of hydrogen ions and ammonia into the filtrate and by absorption of HCO3- from it.
The Proximal Convoluted Tubule reabsorbs 70-80% of electrolytes (especially Na+) and water through its brush border epithelium, making it the primary site of selective reabsorption. Students often confuse PCT with Loop of Henle or mistake the percentage reabsorbed—many think the Loop reabsorbs most water instead of recognizing PCT's role. Remember: PCT = selective reabsorption of useful substances and majority of water/electrolytes; Loop = water reabsorption only in descending limb. Since NEET 2015-2016 tested this concept twice, understand that PCT's high reabsorption capacity is linked to its increased surface area (brush border), not just its length.
This paragraph was tested 2 times in NEET.
[NEET 2016 Phase 2] The part of the nephron involved in the active reabsorption of sodium is:
[NEET 2015 / AIPMT 2015] Human urine is usually acidic because:
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