Excretory System
Biology · उत्सर्जन तंत्र · 12 facts
Excretion: removal of metabolic waste from body
Kidneys: pair of bean-shaped organs; main excretory organs
Nephron: structural and functional unit of kidney; ~1 million per kidney
Kidney functions: filters blood, removes urea, regulates water/salt balance
Urine formation: filtration -> reabsorption -> secretion
Urine path: kidney->ureter->urinary bladder->urethra
Dialysis: artificial kidney; filters blood when kidneys fail
Liver: excretes bile pigments; Lungs: excrete CO2; Skin: sweat(urea+salt)
Urea: main nitrogenous waste in humans(ureotelic)
Birds/reptiles: uric acid(uricotelic); Fish: ammonia(ammonotelic)
Kidney stones: calcium oxalate deposits; drinking water prevents
Each kidney about 10cm long; left slightly higher than right