Excretion Human Excretion Excretion process of removing waste

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 �Excretory substances – water, carbon dioxide, urea, excess mineral salts.

Human Excretion (cont’d) Excretory organ Excretory products Skin Water, mineral salts, urea Lungs Carbon dioxide, water vapour Kidneys Water, mineral salts, urea

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

Urinary system

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 1. Remove nitrogenous waste products e. g urea 2. Balance the water and mineral contents 3. Maintain the p. H 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 : 1. 2. 3. Bacterial infection Injury High blood pressure � Two ways to treat kidney failure 1. Haemodialysis 2. 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Urinary system (cont’d) �Haemodialysis �Dialysis machine works in similar to kidney �Blood is withdrawn and circulated through the machine �Blood flows through a dialysis tube, surrounded by dialysing solution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) Excretory products Source Method of exrection Carbon dioxide Respiration • Diffuse through stomata Oxygen Photosynthesis • Diffuse through stomata Water Photosynthesis • Transpiration 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