1. Mammals

2. Excretory System To filter out and eliminate metabolic, nitrogenous wastes and help maintain homeostasis –Gets rid of excess H 2 O, salt, vitamins, toxins, minerals, and heat –Nitrogenous Waste: cells create ammonia which the liver converts to urea (urea is the yellow color in urine) Job:

3. Humans/Mammalian Excretory System: Lungs: –Eliminates CO2, excess water and heat. Sweat glands: –Eliminates excess water, heat and salt. Kidneys: –Eliminates nitrogeneous waste, salt and water.

4. 2 kidneys-reddish bean shaped organ –Size of a clenched fist –Lie along in small of back Excretory System

5. Structure of a nephron Each kidney is made up of one million+ nephrons (filtering unit) Blood enters kidney via the renal artery Blood is pushed through a nephron where excess H2O, salt, toxins, minerals, urea is filtered out.

6. Structure of a nephron Blood enters the bowman's capsule Capsule filled w/ glomerulus( ball of blood vessels) All substances are filtered out Cleaned blood reenters circulatory system via the renal vein.

7. Structure of a nephron Impurities travel along the renal tube which leads to center of kidney. Some items reenter blood; impurities empty into the renal pelvis

8. 3 Main Parts of a Kidney 3-parts –Cortex-outer portion of kidney –Medulla-inner region –Renal pelvis- hollowed out area where all waste gathers.

9. Urine Formation All nephrons empty into renal pelvis Renal pelvis empties into the ureter(1/kidney) Ureter leads to bladder Water and impurities that collect in our bladder make up our urine which exits out the urethra

10. Urine Formation Average Adult: –~1.5-2.3 Liters/day –Greatest amount of water loss Must urinate 500mL to get rid of toxins

11. Nonfunctioning Kidneys

12. Skin weighs 9 lbs!!! Muscle Mass: -1/2 Men -1/4 Women

13. 1 month to replace ALL skin cells