Cue Column | Notes Column

Order of segments | Bowman's capsule → PCT → Descending Limb (Loop of Henle) → Ascending Limb (Loop of Henle) → DCT → Collecting Duct. Mnemonic: "Bring Pure Lemonade Daily, Come!"

Bowman's Capsule | Enclosing glomerulus. Site of ultrafiltration (size-selective). Together = Malpighian body/renal corpuscle.

PCT | 65–70% reabsorption. Glucose, amino acids, Na+, K+, Cl−, HCO3−, water (obligatory osmosis). Secretion: H+, NH3, K+, uric acid. Brush border (microvilli). No hormonal regulation — constitutive.

Descending Limb | Permeable to WATER only. Water exits into hypertonic medulla by osmosis. Tubular fluid becomes progressively concentrated.

Ascending Limb | Permeable to SOLUTES (NaCl) only. NaCl actively pumped out (thick segment via NKCC2) or passively diffuses out (thin segment). Water CANNOT leave. Tubular fluid becomes progressively dilute.

DCT | Conditional (facultative) reabsorption. ADH → water. Aldosterone → Na+ in, K+ out. PTH → Ca2+ reabsorption. Secretion: H+, K+, NH3.

Collecting Duct | Water reabsorption under ADH. Urea recycles into medullary interstitium. Final urine composition determined here.

Summary

Each nephron segment has distinct transport properties. PCT handles bulk reabsorption (65–70%), the loop of Henle creates the osmotic gradient, the DCT allows hormonal fine-tuning, and the collecting duct delivers the final concentrated or dilute urine.