Excretory System Job: To filter out and eliminate metabolic, cellular waste -in the form of nitrogenous wastes Nitrogenous Waste: cells create ammonia which the liver converts to urea Urea is the yellow in our urine -filters outs and gets rid of excess: water, salts, vitamins, toxins, minerals and heat.

Excretory System Humans have 2 kidneys -reddish bean shaped organ -Size of a clenched fist -Lie along the small of back

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

Urine Formation All nephrons empty into the pelvis/center of the kidney. The center of the kidney empties into the ureter. Ureter leads to bladder Water and impurities that collect in our bladder make up our urine which exits out the urethra

The Kidneys A. renal vein B. renal artery C. ureter D. medulla Nephron A. renal vein B. renal artery C. ureter D. medulla Where nephrons are located. E. renal pelvis F. cortex

Urine Formation Average Adult: ~1.5 Liters/day Responsible for the greatest amount of water loss in our bodies. Must urinate 500mL/day to get rid of toxins -You have 2 kidneys but can live with one if need be.

Nonfunctioning Kidneys Dialysis: medical treatment to remove the toxins a healthy kidney would normally remove.