The excretory system removes waste from the body through the skin, lungs, liver, large intestines, and kidneys. The kidneys are the most important organ as they regulate blood pH and remove excess water and urea to create urine. Urea is formed when ammonia combines with carbon dioxide and is excreted through the ureters, bladder, and urethra as urine. The lungs, skin, and large intestines also remove other wastes like carbon dioxide, water, and solid wastes to help maintain homeostasis.

1. Excretory System

2. Excretion Excretion is the removal of wastes Wastes from: Cellular respiration Digestion of food Cellular activities

3. Skin Your skin is very important to the excretory system. Excretes excess Water Urea Heat

4. What is Urea? A common metabolic cellular waste product is ammonia. It can raise the pH of blood. The human body can combine ammonia and excess CO2 to make Urea. Urea is very soluble in water, making it an easy way to excrete excess nitrogen

5. Lungs? The lungs are an important organ of the excretory system But what wastes do they get rid of?

6. Carbon Dioxide Carbon Dioxide is a waste product of cellular respiration It makes the blood acidic Our body needs to get rid of it

7. Diffusion We have no special process for CO2 removal Rely on simple diffusion Alveoli High to low concentration Lungs

8. Liver Liver is responsible for detoxification of the body It converts ammonia to urea

9. Cirrhosis Scarring of the liver Usually caused by alcoholism

10. Large Intestines Removal of water from solid wastes Excretion of solid wastes The act of defecation is not considered a part of excretory system

11. Kidneys Kidneys are the most important organ of the excretory system Regulate pH of the blood Remove excess water, and urea to create urine

12. Urinary System Kidneys feed Ureter Ureter connects to Bladder Bladder stores urine Excreted through Urethra

13. Excretion and Homeostasis Excretion is essentially a process of maintaining homeostasis To maintain a constant internal environment all metabolic wastes need to be removed