form 3, chapter 3, excretion

• Excretion is a process of eliminating metabolic waste products from the body.
• The human excretory system comprises of three major organs which are the skin, lung and kidneys.
• The sin and kidneys excrete water, urea and mineral salts while the lungs excrete water and carbon dioxide.
• Excretion is very important to humans.
• The human urinary system comprises of the kidneys, ureters, urinary bladder and urethra.
• The kidneys filter the blood.
• The kidney consists of the capsule, cortex, medulla and pelvis.
• Kidney problems cause an increase of excretory products and toxic substances in the blood.
• Diabetes is a condition tat occurs when the glucose level in the body is very high.
• We are encouraged to drink a lot o water to assist in eliminating toxic substances such as urea.
• Kidney failure can be treated by dialysis or kidney transplant.
• Plants do not have special excretory organs.
• Plants eliminate carbon dioxide and water during respiration while oxygen is eliminated during photosynthesis.
• Excretory products of plants include complex substances such as resin and latex.
• Complex substances are stored in the leaves, fruits, flowers and stem. The complex substances are eliminated when these parts fall off.
• Some excretory products from plants are beneficial while some are dangerous.
• Most of the harmful excretory products of plants are from the alkaloid group.