1. Circulatory System

2. What’s the Function of the Cardiovascular System? Carries needed substances to cells Carries waste products away from cells

3. Blood Vessels: Arteries Arteries: large thick walled muscular elastic vessels that carry oxygenated blood away from the heart. Blood is under pressure pushed through by heart pumping. Arteries branch off from heart divide into smaller vessels called arterioles. Arterioles enter tissues where they branch in capillaries.

4. Capillaries Microscopic blood vessels. Walls are one celled thick Blood cells move through in single file line. Capillary walls enable nutrients and gases to diffuse easily between blood cells and surrounding tissue cells.

5. Veins Veins: large blood vessels that carry blood from tissues back toward the heart. Blood is not under pressure. Veins in arms and legs have valves that prevent blood from flowing backward.

6. Your Heart Main function of the heart is to keep blood moving constantly throughout the body. Large organ made of cardiac muscle that are rich with mitochondria Mammalian hearts have four chambers. –atria –ventricles