Excretion

Excretion

1. Excretion is the removal of the waste products of chemical reactions in the body

2. The Organs of Excretion

   • Lungs
     • Carbon dioxide and water
   • Kidneys
     • salts, urea and water
   • skin
     • salts and water

3. Functions of the Parts of the Urinary System

   • Renal Artery
     • Carries blood with waste products into the kidneys
   • Kidney
     • Filters waste from the blood, forming urine
   • Renal Vein
     • carries purified blood out of the kidney
   • Ureter
     • Carries urine to the bladder
   • Bladder
     • Stores Urine
   • Urethra
     • excretes urine

4. Filtration in the Kidneys

   • blood entering the kidneys contains useful and waste materials
   • useful and waste materials are filtered from the blood in the kidneys
   • useful materials are then reabsorbed back into the bloodstream
     • e.g. glucose and water
   • materials left in the kidneys form urine
     • urea, salts and some water

5. Functions of the Kidneys

   • To remove waste products from the blood
   • To control the amount of water and salts in the body

6. Skin

   • Main Functions
     • To excrete wastes
     • To protect the body from the entry of organisms that can cause disease
     • To act as a sense organ
     • to control the temperature of the body
   • Sweat
     • contains salt + water
     • made by sweat glands under the skin
     • passes up through sweat ducts
     • passes out through swear pores
     • excretes (salt and water) and helps to cool the body when it evaporates