Excretion (in humans)

• What is excretion?

  Excretion is the removal of waste substances, toxic substances and excess substances from living organisms.
• The excretory organs :

  • Lungs
  • Liver
  • Kidneys
• The Excretory Organs & Waste Substances

  Excretion happens to remove waste substance that are either:

  • toxic
  • excess to our needs

  There are 3 organs involved in human excretion.

  • the lungs excrete carbon dioxide
  • the liver converts excess amino acids into urea 
  • the kidneys excrete 
  • urea
  • excess water 
  • and excess salts.
• Carbon Dioxide is one of the products of aerobic respiration. It is excreted through the lungs after being transported there dissolved in the blood plasma.

  If carbon dioxide builds up, it can become toxic.