THE EXCRETORY SYSTEM Chapter 4 Section 3 Pages

Objectives: *Describe the role of the excretory system *Identify the major organs in the excretory system & explain their functions *Analyze how the digestive & excretory systems work together Excretion: The body’s removal process for wastes. *Maintains homeostasis by getting rid of harmful waste materials in the body. The excretory system is the system in the body that collects wastes produced by cells and removes the wastes from the body

Urea: A chemical that comes from the break down of proteins. Kidneys: Major organs of the excretory system. They eliminate urea, excess water, and other wastes. Urine: Watery fluid produced by your kidneys. Ureters: Two narrow tubes from the kidneys to the bladder. Urinary Bladder: Saclike muscular organ that stores urine. Urethra: Small tube from the bladder to the outside of your body. This tube allows urine to leave your body.

Nephrons: Tiny filtering factories that remove wastes from the blood and produce urine. The nephrons filter wastes in 2 stages: *First – Wastes and needed materials (like glucose) are filtered out of the blood. *Second – Much of the needed material is returned to the blood, and the wastes are eliminated from the body. Excretion maintains homeostasis by keeping the body’s internal environment stable and free of harmful levels of chemicals. In addition to the kidneys, organs of excretion that maintain homeostasis include lungs, skin, & liver.

Kidneys regulate the amount of water in your body. It helps you maintain homeostasis. You need 2 liters of water per day. Lungs: When you breathe out, carbon dioxide & some water are removed from your body. Skin: Sweat glands in your skin excrete water and some chemical wastes in sweat. Liver: Produces urea by breaking down protein *Converts hemoglobin molecules into bile *Breaks down fat *The liver is the recycling factory