1. Aim: How does excretion maintain homeostasis ? HW #17 Text – read pages 985-989 Ans ques. 2 and 4 on page 989

2. Digestive wastes (undigested food) is the elimination of feces. It moves into the large intestine for compaction.

3. Wastes of metabolism are....products of cell processes that must be removed from the organism or they will become toxic. nitrogenous wastes - urea excess salt and water Carbon dioxide

4. Your Body’s Filter Have you ever seen a water- purification system attached to a faucet? This system removes impurities from the water such as arsenic or other chemicals that can be harmful to people. As water passes through the filters contained in the system, the impurities are trapped on the surface of the filters. Eventually, the water that comes out of this purifier is free of the impurities.

5. Pg 985 answer the questions 1. Your body has its own system for filtering blood. Why might the blood in your body need to be filtered? 2. What organ(s) filter your blood? 3. How do you think the filtered materials leave your body?

6. Aim: How does the excretory system maintain homeostasis? Do now: State the two types of wastes How are the two types of wastes disposed of?

7. Excretory System The Kidneys 1.Kidney Structure 2.Filtration 3.Reabsorption The Skin (Integument) Respiratory System (carbon dioxide)

9. Renal Artery Renal Vein Kidney Ureter Bladder Urethra Cortex Medulla

10. Kidney Nephron Cortex Medulla Renal artery Renal vein Ureter To the bladder Bowman’s capsule Glomerulus Capillaries Collecting duct To the ureter Loop of Henle Artery Vein Figure 38–17 Structure of the Kidneys Section 38-3

11. Filtration Most filtration occurs in the glomerulus. Blood pressure forces water, salt, glucose, amino acids, and urea into Bowman’s capsule. Proteins and blood cells are too large to cross the membrane; they remain in the blood. The fluid that enters the renal tubules is called the filtrate. Reabsorption As the filtrate flows through the renal tubule, most of the water and nutrients are reabsorbed into the blood. The concentrated fluid that remains is called urine. Secretion Substances such as hydrogen ions are transferred from the blood to the filtrate. Figure 38–18 The Nephron Section 38-3

12. Vein Artery Shunt Air detector Dialysis machine Blood pump Blood in tubing flows through dialysis fluid Used dialysis fluid Compressed air Fresh dialysis fluid Figure 38–19 Kidney Dialysis Section 38-3