THE EXCRETORY SYSTEM Section 3.3

Excretion Excretion = the process of removing waste CO2 = respiratory system Solid waste= digestive system  this is not a waste product, but instead left over undigested food materials such as fiber Wastes dissolved in water = excretory system Excretion

How the Excretory System works… 1a) Cells waste diffuses into blood stream 1b) Liver waste dissolves in blood stream Proteins are broken down by the liver for energy and Ammonia Liver also changes ammonia to a less toxic substance called urea (liver waste) 2) All blood then passes through kidneys (1 L/min) 2b) Tiny tubes in kidneys, called nephrons, collect waste from blood vessels (filters) 2c) Ureter carries waste to bladder = urine Urine exits body through the urethra Without a method of getting rid of waste, cells would soon poison themselves and die

KIDNEYS In addition to filtering your blood, kidneys also maintain the balance of water in your body to keep blood pressure in check

Excretory Video