1. H EART AND B LOOD V ESSELS

2. B LOOD V ESSELS Arteries From heart to tissue Usually carry oxygenated blood Branch into arterioles Veins From tissues back to heart Usually carry deoxygenated blood Venules Capillaries Small, thin Allow diffusion into tissues

3. A RTERIES & A RTERIOLES 3 layers of tissue Endothelium Connective tissue and smooth muscle Connective tissue with elastic/collagen fibers Smooth muscles in arterioles control blood pressure and volume of blood to tissues: Vasoconstriction Vasodilation Exercise increases vasodilation in arterioles of muscles

4. V EINS AND V ENULES Blood flows from capillaries to venules to veins Large diameter, some smooth muscle Pressure is lower, farther from heart Valves prevent back flow

5. H EART Basic Structure: Atrium – receiving chamber Ventricle – pumping chamber Evolution Fish 1 atrium, 1 ventricle Single circuit of blood vessels Amphibians, Most Reptiles 2 atria, 1 ventricle Double circuit Conus arteriosus separates oxygen rich & poor blood

6. H EART, CONT. Birds, Mammals & crocodilians 2 atria, 2 ventricles Conus arteriosus  aorta & pulmonary arteries Ventricle separated by septum Double circuit http://trc.ucdavis.edu/biosci10v/bis10v/media/ch2 2/circulatory_systems.html http://trc.ucdavis.edu/biosci10v/bis10v/media/ch2 2/blood_circulation.html

7. H UMAN HEART Hollow, muscular organ Cardiac Muscle Enclosed by the pericardium Septum separates left and right sides of heart In fetal heart, foramen ovale allow blood to flow from right to left atrium Why?? Closes and leaves fossa ovalis

9. H EART V ALVES AV valves Right – tricuspid Left -mitral valve or bicuspid Chordae tendinae hold valves in place As blood enters atria, pressure forces valves to open As ventricles contract, back pressure forces valves closed

10. H EART VALVES, CONT. Semilunar valves Exit from heart Aortic Pulmonary As ventricles contract, valves open As ventricles relax, blood pressure in arteries is higher, valves close http://www.bostonscientific.com/templatedata/im ports/HTML/CRM/heart/interact_4.html

12. P ATTERN OF CIRCULATION Vena cava returns blood from body to heart Right atria, right ventricle to pulmonary artery Lungs  gas exchange Pulmonary vein to left atrium to left ventricle Aorta to body

13. Y OUR H EART I N ACTION http://www.bostonscientific.com/templatedata/im ports/HTML/CRM/heart/interact_6.html