Advanced Cardiac Care in the Streets Understanding EKGs Ray Taylor Valencia Community College The Anatomy of the Heart { Structure }

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Anatomy of the Heart ä Objectives: ä Describe the chambers of the heart ä Atria ä Ventricles ä Identify the location, shape, and size of the heart ä Name the layers of the heart ä Name the valves of the heart

Anatomy of the Heart ä Objectives [ continued ] ä Describe the structure and function of the blood vessels ä Arteries ä Veins ä Capillaries ä Describe the coronary circulation ä Discuss the concept of pulmonary circulation ä Discuss the concept of systemic circulation

Anatomy of the Heart ä The Heart is muscle ä Myocardium - heart muscle ä “Two-sided pump” ä Atrium [ atria ] ä Small upper chambers ä Separated by interatrial septum ä Receiving chambers ä Fill ventricles ä Ventricles ä Lower chambers ä Separated by interventricular septum

Location, Size, and Shape of the Heart ä Located in Mediastinum ä Lying in front of spinal column, behind sternum, and between lungs ä 2/3 lies to left of midline sternum ä Apex lies just above diaphragm ä Base lies at level of the second-third rib ä Size of owner’s closed fist ä PMI

Cardiovascular Anatomy ä Tissue Layers ä Endocardium ä Myocardium ä Pericardium ä Visceral Pericardium ä Parietal Pericardium

Layers of the Heart ä Pericardium - closed, two- layered sac ä Parietal Pericardium - tough, nonelastic, fibrous connective tissue ä Visceral Pericardium - thin, serous inner layer of pericardium ä Pericardial Fluid

The Heart Wall ä Epicardium - smooth outer surface contiguous with visceral pericardium ä Myocardium - thick, middle layer of the heart, composed of cardiac muscle cells, responsible for ability to contract ä Endocardium - innermost layer, composed of connective tissue

Valves of the Heart ä Four valves allow blood to flow in one direction ä Two Sets ä Atrioventricular Valves ä Semilunar Valves

Cardiovascular Anatomy ä Valves ä Atrioventricular Valves ä Tricuspid Valve ä Mitral Valve ä Semilunar Valves ä Aortic Valve ä Pulmonic Valve ä Chordae Tendonae

Atrioventricular Valves ä Located between atria and the ventricles ä Allow flow from atria into ventricles ä Prevent flow backward from ventricles ä Tricuspid Valve - three cusps - located between right atrium / right ventricle  Mitral / Bicuspid Valve - has two cusps - located between left atrium / left ventricle

Semilunar Valves ä Prevent backflow of blood into the ventricles. Each valve contains three semilunar, or moon- shaped, cusps. ä Pulmonic Valve- located between right ventricle and pulmonary artery ä Aortic Valve - located between left ventricle and trunk of aorta

Heart Valves Function ä Chamber pressure governs opening and closing of heart valves ä Ventricular Systole [ contraction of ventricles ] atrioventricular valves are closed and semilunar valves are open ä Ventricular Diastole [ relaxation of ventricles ] atrioventricular valves are open and semilunar valves are closed

Cardiovascular Anatomy ä Anatomy of the Peripheral Circulation ä Blood vessels are the “container” for fluid or blood ä General Structure ä Poiseuille’s Law ä Arterial System ä Arteries, arterioles, and capillaries ä Venous System ä Veins, venules, and capillaries

ARTERIES ä Thick wall and muscular ä Function under high pressure ä Carry blood AWAY FROM heart ä Regulate blood pressure by changes in peripheral vascular resistance ä Arteries - larger vessels ä Arterioles - small vessels

Arterial Wall Layers NameLayerTissue Type Tunica intimaInnermostConnective and elastic Tunica mediaMiddleSmooth muscle, elastic, and collagen Tunica adventitiaOutermostConnective

VEINS ä Vessels that carry blood back to the heart ä Venules - smaller vessels ä Operate under low pressure

CAPILLARIES ä Tiny blood vessels whose walls are thinnest of all ä Vast majority of gas exchange occurs ä Circulation - movement through a course [ body ] that leads back to initial point [ heart ]

Cardiovascular Anatomy ä Coronary circulation ä Right coronary artery ä Left coronary artery ä Left anterior descending ä Circumflex ä Collateral Circulation

Pulmonary Circulation ä Blood flow between the heart and lungs ä bloodleaves heart through right ventricle, travels into PULMONARY artery to lungs, and back through PULMONARY veins to left atrium

Systemic Circulation ä Blood flow between the heart and body ä blood leaves the left ventricle and travels through the arteries, capillaries, and veins of the BODY SYSTEM and back to the right atrium

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