Counter current mechanismप्रतिधारा क्रियाविधि

NCERT Fig 16.6 · interactive diagram

Parts and their functions

• Descending limb (अवरोही भुजा) — Water leaves into the hyperosmotic interstitium.
• Ascending limb (आरोही भुजा) — NaCl transported out; no water follows.
• Henle’s loop (हेनले लूप) — Counter current flow builds the gradient.
• Vasa recta (वासा रेक्टा) — Exchanges NaCl and returns it to the interstitium — keeps the gradient.
• Collecting duct (संग्राहक नलिका) — Water reabsorbed (ADH) → concentrated urine; some urea leaks out.
• Water out (जल बाहर) — From descending limb and collecting duct.
• NaCl out (NaCl बाहर) — Pumped from the ascending limb.
• Urea recycling (यूरिया) — Urea from the collecting duct adds to medullary osmolarity.
• Osmotic gradient (परासरणी प्रवणता) — 300 (cortex) → 1200 mOsmol L⁻¹ (inner medulla).

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 16.6. Report a mistake