HUMAN EXCRETION• Excretion: process of removing substances that are of no use or in excess from the body.• Urea, carbon dioxide, excess mineral salts and excess water are examples of excretory products. • eliminated through specific excretory organs, like the skin, lungs and kidneys.• If these excretory products are allowed to accumulate in the body, it will become poisonous (toxic) and endanger health.
• skin excretes waste products in the form of sweat.• The sweat gland absorbs excretory products like water, mineral salts and urea from blood capillaries around it.• Sweat is eliminated from the sweat gland through sweat pores to the surface of the skin.
LUNG• eliminate carbon dioxide and water.• Carbon dioxide in the blood capillaries diffuses into the alveolus and is eliminated from the lungs when exhaling.• Water is eliminated from the lungs in the form of water vapour.
KIDNEY• many substances are eliminated in large quantities through kidney• Filter blood and produce urine• Urine: yellowish liquid that contains water, mineral salts and urea
URINARY SYSTEM IN HUMAN BEINGS• consists of (a) a pair of kidneys (c) a urinary bladder (b) a pair of ureters (d) urethra
• Blood is carried to each kidney by renal artery and away from it by renal vein• Blood is filtered within kidney• Waste products (e.g. urea) and excess substances (e.g. mineral salts and water) are converted into urine• Ureters carry the urine from kidneys to the urinary bladder• Urinary bladder stores urine and gradually expands like balloon• When muscle in the wall of bladder contract, urine is expelled to exterior via urethra. This process is called urination
• dark red in color and are bean-shaped.• internal structure of the kidney is kidney divided into (a) the outer part which is dark red in colour named cortex (b) the inner part which is light red in colour named medulla.• Functions of the kidney • eliminating excess water and mineral salts from the body • Keep the amount of water and mineral salts in the body in balance • regulating the blood concentration • helping to remove nitrogenous substances like urea and uric acid from the body
KIDNEY FAILURE• Maybe due to: • Bacterial infection • Injury • High blood pressure• 2 ways to treat kidney failure: • Dialysis machine • Kidney transplant
KIDNEY HEALTH• Ways to maintain healthy kidneys include: • Limiting salt and protein intake • Maintaining blood sugar control for diabetics • Drinking at least 8 glasses of water a day
EXCRETION IN PLANTS Excretory product Source UseLatex Rubber tree To make vehicle tyresRennin Certain tree stems like the To make varnish and gum casuarina treeGum Certain tree stems like the To make cough medicine acacia treeAcid (tannic acids or Bark of plants like the tea, To make inktannin) coffee and mangrove treeQuinine Bark of cinchona To make medicine to treat malariaOil Flowers or leaves of certain To make perfume and trees ointment for insect bites
Excretory product Source Reason for dangerOpium Flowers of the poppy plant Are drugs that ruin healthMorphine Made from opiumHeroin Made from morphineCocaine Leaves of coca plantGanja Leaves and dried flowers of the cannabis sativa plantCaffeine Coffee beans Causes addictionNicotine Tobacco leaves Smoking damages the lungs and the breathing channel