Human ExcretionExcretion – 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, kidneysExcretory 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
1. Remove nitrogenous waste products e.g urea2. Balance the water and mineral contents3. Maintain the pH of the blood and tissue fluid
Urinary system (cont’d)Ways to maintaining
healthy kidneys:Taking urine and blood
testLimit protein and salt
intakeMaintaining blood sugar
control (for diabetics)Drink, at least 8 glass of
water per dayLearn about symptoms
of kidney failure
Urinary system (cont’d)Living with kidney failure
Human can survive with one healthy kidneyCause of kidney failure :
1. Bacterial infection2. Injury3. High blood pressure
Two ways to treat kidney failure1. Haemodialysis2. 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Blood is withdrawn and circulated through the machine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 solutionis discarded
Excretion in plantsPlants
produce relatively small amount of waste products.
less active – accumulate waste slowlyDo 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 •TranspirationSome other waste productsLatex, resins, gumStored in plants and released when the plants
die and decaySome are useful to humans
Latex – manufacturing Resins – paint industry