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)

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 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Blood is withdrawn and circulated through the machine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

Urinary system (cont’d)Kidney transplant

The kidney of donor should be match to the patient

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