2. carry blood away from heart usually O 2 rich Pulmonary artery – artery leading from heart to lung (deoxygenated) connective tissue and muscle walls elastic and thick precapillary sphincters control blood flow Arteries

3. carry blood to the heart usually O 2 poor Pulmonary vein – vein leading from lung to heart (oxygenated) valves push blood towards heart smooth surface Veins

4. Valves prevent backflow Less pressure than arteries Skeletal muscles contract and pump blood back to the heart Blood Flow in Veins

5. smallest blood vessels for gas exchange High SA Thin walls connect arteries/arterioles to veins/venules Exchanges: carbon dioxide/oxygen and nutrients/waste Capillaries

6. Arteries to arterioles to capillaries Capillaries to venules to veins Arterioles and Venules

7. Systemic Circulation – oxygenated blood to tissue and deoxygenated blood to heart Pulmonary Circulation – between lungs and heart – deoxygenated blood goes to lungs and oxygenated blood goes to heart Circulation Types

8. Cardiac Circulation – circulation of blood within the heart Circulation Types

9. How do nutrients pass from the blood vessels into the individual cells!?!?!?! DIFFUSION: molecules move across a membrane from an area of higher concentration to an area of lower concentration Nutrient Exchange

10. In other words … If the blood in the capillary contains a higher concentration of oxygen than does the fluid next to it, the oxygen moves spontaneously into the fluid by diffusion Nutrient Exchange