Cheat sheet · Class 11 · CBSE · Science Biology
Excretory Products and their Elimination cheat sheet
The whole chapter on one page: key formulas, facts and the points to remember, for quick revision before a test.
CBSE Class 11 · Biology
Cheat sheet
Chapter 16Excretory Products and their Elimination
Urine formation: Filtration, Reabsorption, Secretion.
1. Nitrogenous Wastes
| Type | Waste | Example |
|---|---|---|
| Ammonotelic | ammonia | bony fish |
| Ureotelic | urea | mammals, frogs |
| Uricotelic | uric acid | birds, reptiles |
2. Nephron
- Malpighian body = glomerulus + Bowman's capsule.
- PCT reabsorbs most nutrients and ~70–80% electrolytes and water.
- Henle's loop: counter-current mechanism concentrates urine.
- DCT and collecting duct: conditional reabsorption.
GFR ≈ 125 mL/min (180 L/day); urine ≈ 1.5 L/day.
3. Regulation
ADH (vasopressin)
Increases water reabsorption; prevents diuresis.
RAAS
Low BP → renin → angiotensin II → aldosterone → Na⁺ and water reabsorption.
ANF
From atria; vasodilation, checks RAAS.
4. Disorders
- Uremia: urea build-up → haemodialysis.
- Renal calculi; glomerulonephritis.
- Diabetes insipidus: low ADH.
5. Key Points
- Micturition reflex.
- Skin, lungs and liver also excrete.
- Vasa recta helps the counter-current system.
- Juxtaglomerular apparatus releases renin.
Remember: 3 waste types | nephron parts | ADH, RAAS, ANF
Excretory Products and their Elimination: questions and notes
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