Anatomy of the Cardiovascular System

Consists of: heart, arteries, veins, capillaries

Heart Four chamber muscular organ Comparable to the size of a closed fist Located in the mediastinum Behind sternum Between 2nd and 6th ribs Between T5-T8 Apex – base of heart Located at the 5th intercostal space Superiorly the superior mediastenum Rested on diaphragm inferiorly

Anatomy of the heart 1-Pericardium – loose fitting sac surrounding the heart Parietal layer: lines the inside of the mediastenum Visceral layer: adheres to outside of the heart Pericardial space: between parietal and visceral layer Filled with 10-15mL of pericardial fluid Decreases friction

2-Wall Epicardium – outer layer Epicardium = visceral pericardium plus the loos connective tissue Myocardium – thick, branched contractile layer of cardiac muscle cells allow heart to function as a single unit Endocaridium – interior of cardiac wall composed of Endothelial tissue

3-Chambers of the Heart Atria – two (left and right atria), superior champers, they are “Receiving chambers” because they receive blood from veins . Atria separated by interatrial septum. Ventricles – two (Left & right)inferior chambers “pumping chambers” composed of thick muscular wall to increase force of pumping action. Ventricles separated by interventricular septum

4-Valves of the Heart Permit blood flow in one direction during circulation 1-Atrioventricular valves (AV valves) Between atria and ventricles 2-Semilunar (SL valves) Between : A-R ventricle and pulmonary arteries B-L ventricle and aorta

Atrioventricular Valves 1-Tricuspid valve Between R atrium and ventricle 3 flaps of endocardium 2-Bicuspid valve Betwn L atrium and ventricle Also called mitral valve Two flaps of endocardium

Semilunar Valves Pulmonary semilunar valve Btwn R ventricle and pulmonary trunk Aorta semilunar valve Btwn L ventricle and aorta

5-Blood Supply to the Heart Right and left coronary arteries First branches off aorta Most of the blood goes to the L ventricle

Anastomosis: Connections between blood vessels that allow for collateral circulation Few exist between large branches of coronary arteries, they do exists between smaller branches of the R and L coronary arteries In presence of an obstruction in a large artery ischemia will result ( infarction )

5-Conduction System of the Heart Four structures composed of modified cardiac muscle Sinoatrial Node (SA Node) Pacemaker of the heart Atrioventricular Node (AV Node) Located in the Left lower border of R atrium

Atrioventricular Bundle (Bundle of His) Bundle of specialized cardiac muscle fibers originating in the AV node Bundle branches Purkinje fibers Extend into the walls of the ventricles

Types of Blood Vessels Artery – carries oxygenated blood away from the heart “distributors” Arteriole: small artery Vein – carries unoxygenated blood towards the heart Venule: small vein Capillary: regulate the blood flow into capillaries

Circulatory Routes Systemic Circulation – blood flow from the L ventricle to the body & back to the R atrium Pulmonary Circulation – blood flow from the R ventricle to the lungs and back to the L atrium