2The Cardiovascular System A closed system of the heart and blood vesselsThe heart pumps bloodBlood vessels allow blood to circulate to all parts of the bodyThe function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products
3Systemic Circulation – delivers blood to all body cells and carries away waste Pulmonary Circulation – eliminates carbon dioxide and oxygenates blood (lung pathway)
4The distal end of the heart is called the apex. Structure of the HeartAbout the size of a fist.Located in the mediastinum (space between lungs, backbone, sternum), between the 2nd rib and the 5th intercostal space.The distal end of the heart is called the apex.
6Protective Coverings of the Heart Fibrous Pericardium encloses the heart and has 2 layersVisceral pericardium (inner)Parietal pericardium (outer, attached to diaphragm, sternum and vertebrae)Pericardial cavity contains fluid for the heart to float in and reduces friction
7Wall of the Heart Epicardium – outer layer, reduces friction Myocardium – middle layer, mostly cardiac muscleEndocardium – thin inner lining, within chambers of the heart
8Heart Chambers & Valves Your heart is a double pump. Circulation is a double circuit: Pulmonary (lungs only) and systemic (rest of the body)Heart has 4 chambers:2 Atria – thin upper chambers that receive blood returning to the heart through veins. Right and Left2 Ventricles – thick, muscular lower chambers. Receive blood from the atria above them. Force (pump) blood out of the heart through arteries. Right and leftSeptum – separates the right and left sides of the heart
9Valves of the Heart Allow one-way flow of blood 4 total—2 Atrioventricular Valves (AV) & 2 Semilunar valvesLeft Atrioventricular valve – also called the bicuspid valve or mitral valve. Between left atrium and ventricleRight Atrioventricular valve – also called the tricuspid valve. Between right atrium and ventricleAortic Semilunar – or just aortic valve. Between the left ventricle and the aortaPulmonary Semilunar, or just pulmonary valve. Between the right ventricle and the pulmonary trunk
10The cusps (flaps) of the bicuspid and tricuspid valves are anchored to the ventricle walls by fibrous “cords” called chordae tendineae, which attach to the wall by papillary muscles. This prevents the valves from being pushed up into the atria during ventricular systole.
11Mitral = bicuspid (left side) Tricuspid (right side) Aortic and Pulmonary are both semilunar valves
13Blood Flow Through the Heart Blood that is low in oxygen and high in CO2 enters right atrium through the superior and inferior vena cavaeFrom (contraction) right atrium, through the tricuspid valve, blood travels to the right ventricleFrom (contraction) the right ventricle, blood leaves the heart as it passes through the pulmonary semilunar valve into the pulmonary trunkPulmonary trunk splits into right and left pulmonary arteries that carry blood to the lungs
14Blood Flow Through the Heart 5. Oxygen is picked up and carbon dioxide is dropped off by blood in the lungs6. Oxygen-rich blood returns to the heart through the four pulmonary veins7. Blood enters the left atrium and travels through the bicuspid (mitral) valve into the left ventricle8. From the left ventricle, (wall contracts) blood leaves the heart via the aortic semilunar valve and aorta9. Oxygenated blood flows to all body tissues
16Heart ContractionsContraction is initiated by the sinoatrial node (SA node)Sequential stimulation occurs at other autorhythmic cells, forcing cardiac muscle depolarization in one direction—from atria to ventriclesOnce SA node starts the heartbeatImpulse spreads to the AV nodeThen the atria contractAt the AV node, the impulse passes through the AV bundle, bundle branches, and Purkinje fibersBlood is ejected from the ventricles to the aorta and pulmonary trunk as the ventricles contract