2. Excretory System Purpose Your body requires things from the environment to survive: Oxygen Food Water However, when obtaining and using these resources, there is almost always substances we can’t use. In fact, many of these substance are toxic to our bodies in even small quantities.

3. Deadly!

4. Body’ solution: Excretory System Purpose: Remove waste to maintain homeostasis Players in the Excretory System Skin Lungs Liver Kidneys

5. Skin Purpose in the excretory system: Excrete excess water, salt, and small amount of urea.

6. Lungs Purpose: Remove excess CO2 from the body. Lung are important in respiration (bringing oxygen to your cells) However, removing the major byproduct of respiration (Carbon Dioxide) is also important. CO2 travels from cells, through veins, to the lungs. Breathing out is your bodies way of removing CO2 waste.

7. Liver Major Purpose: Convert ammonia to urea. When your body breaks down protein (perhaps from say, a cheeseburger), ammonia is made. Ammonia is super deadly. Liver breaks down converts ammonia to urea. Urea is bad, but not nearly as bad as ammonia Urea is transported through the blood to the kidneys. Removed in the kidneys.

8. Other major functions of Excretory system. Helps maintain normal concentration of water and electrolytes Regultes pH Regulates volume of body fluids Control red blood cell production Control blood pressure

11. Kidney remove substances from the blood forms urine reddish brown, bean shaped organ, 12 cm long, 6cm wide, 3cm thick

13. Nephrons 1 million per kidney glomerulus tangled mass of capillaries surrounded by Bowman’s capsule Glomerular Filtration water, salt, glucose, amino acids, urea to Bowman’s capsule Nephrons of both kidneys - 125 ml/minute or 180,000 ml per day 45 gallons

15. Renal Tubes Reabsorption and Secretion Glucose, ions and some water are reabsorbed into the blood stream Urine Water, urea (nitrogen compound) and various salts empty into the collecting duct.

17. Collecting Ducts Millions in each kidney empty into the ureters. Ureters connect to the urinary bladder, a hollow muscular sack that stores urine (0.6L). Urine leaves the body through the urethra. (1.5L-2.3L per day)