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Excretion. Human Excretion. Excretion – process of removing waste substances produce by the metabolic processes from the body . Waste substance left in the body and not removed will become toxic and poison . Excretory organs – skin, lungs, kidneys
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Human Excretion • Excretion – process of removing waste substances produce by the metabolic processes from the body. • Waste substance left in the body and not removed will become toxic and poison. • Excretory organs – skin, lungs, kidneys • Excretory substances – water, carbon dioxide, urea, excess mineral salts.
Human Excretion (cont’d) • Importance of excretion • Disposal of toxic or poisonous substances e.g urea • Disposal of excess subtances e.g salts and water
Urinary system (cont’d) • Human kidney • Dark red, broad bean-shaped organ • Located at the back of the abdomen • Parts : • Cortex – lighter outer region • Medulla – darker inner region • Pelvis – central cavity • Ureter – connects the pelvis to the bladder
Urinary system (cont’d) • Function of the kidneys • Remove nitrogenous waste products e.g urea • Balance the water and mineral contents • Maintain the pH of the blood and tissue fluid
Urinary system (cont’d) • Ways to maintaining healthy kidneys: • Taking urine and blood test • Limit protein and salt intake • Maintaining blood sugar control (for diabetics) • Drink, at least 8 glass of water per day • Learn about symptoms of kidney failure
Urinary system (cont’d) • Living with kidney failure • Human can survive with one healthy kidney • Cause of kidney failure : • Bacterial infection • Injury • High blood pressure • Two ways to treat kidney failure • Haemodialysis • Kidney transplant
Urinary system (cont’d) • Haemodialysis • Dialysis machine works in similar to kidney • Blood is withdrawn and circulated through the machine • Blood flows through a dialysis tube, surrounded by dialysing solution
Urinary system (cont’d) • Haemodialysis (cont’d) • Urea and excess salts diffuse into the dialysing solution • Used dialysing solution is discarded
Urinary system (cont’d) • Kidney transplant • The kidney of donor should be match to the patient
Excretion in plants • Plants • produce relatively small amount of waste products. • less active – accumulate waste slowly • Do not have specialised excretory organs
Excretion in plants (cont’d) • Some other waste products • Latex, resins, gum • Stored in plants and released when the plants die and decay • Some are useful to humans • Latex – manufacturing • Resins – paint industry