1. How does the body release waste and maintain homeostasis? The Excretory System

2. Excretion The excretory system is the system in the body that collects wastes produced by cells and removes the wastes from the body. Excretion is the removal process of wastes from the body.

3. Pathway of Excretion KidneysUreterUrinary BladderUrethra

4. Excretory Structures and Waste Products Urea is a chemical that comes from the breakdown of proteins. Urea, water, and other wastes are eliminated through the kidneys, the major organs of the excretory system. The kidneys act as filters by removing wastes from blood and keeping materials the body needs. The wastes are eliminated through urine, a watery fluid that contains urea and other wastes. The kidneys have nephrons which are tiny filtering factories that remove wastes from blood and produce urine.

5. Excretory Structures and Waste Products Urine flows from the kidneys through the ureters, two narrow tubes that connect the kidneys to the urinary bladder (a saclike muscular organ that stores urine). Urine leaves the body through a short tube called the urethra.

6. Homeostasis Excretion maintains homeostasis by keeping the body’s internal environment stable and free of harmful levels of chemicals. Organs involved in excretion include: 1. Kidneys – filter wastes from blood 2. Lungs – remove carbon dioxide and some water from the body 3. Skin – Sweat glands in the skin remove urea and water through perspiration 4. Liver – urea, caused by the break down of proteins, is produced in the liver; changes hemoglobin from old red blood cells into bile (used in digestion)