1. Excretory System

2. Urinary Purpose: Rid the body of liquid waste –Urea- waste from break down of body protein ~picked up by blood and taken to kidneys

3. Parts Kidneys- filter blood (blood arrives in arteries) –*regulate the amount of water and salt in the blood Nephrons- filters … –1. food, water, salts, & urea from the blood in the capillaries –2. ~ all the food & some water & salts are put back in the blood –3. remaining water, salt, & urea are carried out of the kidneys as urine

4. Ureter carries waste to urinary bladder Urethra remove it from the body

5. The basic unit of the kidney that performs these functions is a tubelike small structure called the nephron that filters blood and modifies the filtrate to produce urine. The blood that is to be filtered enters each nephron in a ball-shaped cluster of capillaries called the glomerulus. The pressure of blood in the glomerulus squeezes the liquid portion of the blood out of the glomerulus through a sieve-like filtering structure. nephronglomerulus.

6. Blood cells are too large to pass through the sieve and most proteins are retained in blood by their size and charged nature. Other small molecules such as salts, amino acids, glucose, water, and urea pass easily into the filtrate. The filtrate that leaves the blood enters a cup-shaped structure around the glomerulus called Bowman's capsule, which forms the starting end of the tubelike nephron. Bowman's capsule,

8. Other excretory members Lungs- rid the body of Carbon dioxide, water, and heat Skin- rids the body of heat, water, and salts (sweat) –2-5 million sweat glands –Evaporation of sweat cools the skin and lowers body temperature

9. Problems Kidney disease- caused by high blood pressure, heredity, or bacterial infection –We can live with only 1 kidney –If both become damaged: Dialysis- pass blood through membrane tubes that are surrounded by liquid ~ the urea, salts, and water diffuse out of the tubing and the fresh blood is put back into the person Transplant- poses possibility of rejection