9/2/20 Cardiac Anatomy & Physiology Myocardial Layers Heart - PDF document

9/2/20 Cardiac Anatomy & Physiology – Myocardial Layers Heart Muscle is compromised of three layers: ◦ Epicardium: serous membrane and is the external surface of the heart ◦ It is surrounded by a thin, though layer of tissue called the Cardiac Pericardium . The pericardium is a double-walled sac which serves as protection for the heart. Anatomy & ◦ A slippery fluid between the two surfaces is called the Pericardial Fluid . This fluid serves as a lubricant and allows for smooth cardiac Physiology contractions. ◦ Myocardium: middle muscular layer Jennifer Cheung, M SN, RN, CCRN ◦ Endocardium: similar to epicardium ◦ Lines the interior heart chambers Image Source: Wikipedia 1 2 Cardiac Anatomy & Physiology – Heart Chambers Cardiac Anatomy & Physiology – Cardiac Valves The heart chambers are two pumps which work together to Cardiac valves ensure blood flows effectively in one direction effectively oxygenate and circulate blood to the tissues of the body through the 4 chambers of the heart ◦ The valves open and close when the heart contracts and relaxes as pressure changes between the chambers Two superior or upper chamber called Atria ◦ Right Atrium ◦ As the valves open and close, the familiar “lub” ”dub” sound can be heard ◦ Left Atrium upon auscultation Two inferior or lower chambers called Ventricles ◦ Right Ventricle The cardiac valves include ◦ Left Ventricle ◦ Atrioventricular valves Bicuspid or Mitral Valve ◦ Tricuspid Valve ◦ Image Source: TexasHeart Image Source: TexasHeart ◦ Semilunar Valves ◦ Pulmonic Valve Aortic Valve ◦ 3 4 Cardiac Anatomy & Physiology – Cardiac Valves Cardiac Anatomy & Physiology – Great Vessels Atrioventricular valves (AV Valves) The great vessels is a term used to describe the four large vessels that bring blood to and from the ◦ The AV valves are located between the atria and ventricles heart ◦ They are made of fibrous flaps called cusps ◦ Superior Vena Cava ◦ Returns blood from the head and arms ◦ Stringy tendinous (ten-din-us) cords, resembling a parachute, connect the valves cusps to papillary ◦ Inferior Vena Cava muscles anchored on the ventricle floor ◦ Returns blood from the trunk and legs ◦ When the ventricles contract, these muscles keep the cusps closed to prevent blood from flowing back into the Atria ◦ Bicuspid or Mitral Valve (two cusps) Image Source: TexasHeart Image Source: TexasHeart Located between the left atrium and left ventricle ◦ ◦ Tricuspid Valve (three cusps) ◦ Located between the right atrium and right ventricle 5 6 1

9/2/20 Cardiac Anatomy & Physiology – Great Vessels Cardiac Anatomy & Physiology – Cardiac Cycle The great vessels is a term used to describe the The heart consists of two pumps which work four large vessels that bring blood to and from the together to oxygenate and circulate blood to the heart tissues ◦ Pulmonary Artery The Cardiac Cycle is composed of ◦ Transports blood from the heart to the lungs ◦ Systole ◦ Pulmonary Veins ◦ After the ventricles contract, pressure in the ventricles exceed the arterial pressure causing the ◦ Transports blood from the lungs back to the heart aortic and pulmonic valves to open ◦ Ejection Fraction: approximately 60% of the blood in the ventricles flows out of the ventricles to the lungs and the body ◦ Diastole ◦ Most of the blood flows passively from the atria to Image Source: TexasHeart Image Source: TexasHeart the ventricles ◦ Atrial Kick: When atria contract, 15-30% of additional blood is forced into the ventricle 7 8 Cardiac Anatomy & Physiology – Systemic Circulation Cardiac Anatomy & Physiology – Pulmonary Circulation A sophisticated network of vessels connect with Pulmonary circulation moves deoxygenated blood the heart and lungs, circulating approximately 5 from the heart through the lungs for oxygenation liters of blood to maintain and sustain the body. and back to the heart Unoxygenated blood The circulatory system is compromised of ◦ Blood returns to the heart via the superior and inferior systemic and pulmonary circulation. vena cava, filling the right atrium ◦ Systemic circulation carries oxygenated blood ◦ Blood flows through the tricuspid valve and into the from the heart, throughout the body (including right ventricle heart muscle via coronary arteries) and Image Source: Wikitonary ◦ Blood is pumped through the pulmonic valve into the deoxygenated blood returns to the heart pulmonary arteries and into the lung where it is oxygenated Image Source: Quizlet 9 10 Cardiac Anatomy & Physiology – Pulmonary Circulation Cardiac Anatomy & Physiology – Coronary Vessels The Right Coronary Artery (RCA) and Left Coronary Pulmonary circulation moves deoxygenated blood Artery (LCA) systems provide blood flow to the heart. from the heart through the lungs for oxygenation Both arteries are the first to branch from the aorta. and back to the heart Left Main Coronary Artery Oxygenated blood ◦ Location ◦ The pulmonary veins receive oxygenated blood and fill ◦ Originates from the left aortic sinus, above the aortic valve the left atrium ◦ Branches into ◦ Blood flows through the mitral valve into the left Left Anterior Descending Artery ventricle ◦ Circumflex Artery Image Source: Wikitonary ◦ ◦ Blood is pumped through the aortic valve and the aorta ◦ Perfuses out into the body ◦ Left heart Image Source: John Hopkins 11 12 2

9/2/20 Cardiac Anatomy & Physiology – Coronary Vessels Cardiac Anatomy & Physiology – Coronary Vessels The Right Coronary Artery (RCA) and Left Coronary The Right Coronary Artery (RCA) and Left Coronary Artery (LCA) system provide blood flow to the heart. Artery (LCA) system provide blood flow to the heart. Both arteries are the first to branch from the aorta. Both arteries are the first to branch from the aorta. Left Anterior Descending Artery (LAD) Circumflex Artery ◦ Location ◦ Location ◦ Left lateral heart ◦ Left posterior heart ◦ Branches into ◦ Branches into Diagonals Marginal ◦ ◦ Septal Perforators Obtuse Marginal ◦ ◦ ◦ Perfuses ◦ Perfuses ◦ Front and bottom of left ventricle ◦ Left atrium Image Source: John Hopkins Image Source: John Hopkins ◦ Front of septal wall ◦ Posterior and lateral side of left ventricle Bundle of His SA node and posterior descending artery ◦ ◦ 13 14 Cardiac Anatomy & Physiology – Coronary Vessels Cardiac Anatomy & Physiology – Coronary Vessels The Right Coronary Artery (RCA) and Left Coronary The Right Coronary Artery (RCA) and Left Coronary Artery (LCA) system provide blood flow to the heart. Artery (LCA) system provide blood flow to the heart. Both arteries are the first to branch from the aorta. Both arteries are the first to branch from the aorta. Right Coronary Artery (RCA) Posterior Descending (PDA) ◦ Location ◦ Location ◦ Originates from right aortic sinus at the base of the aorta ◦ Posterior side of heart ◦ Branches into ◦ Branches into Acute Marginal Right coronary artery ◦ ◦ Inter-ventricular ◦ ◦ Perfuses ◦ SA Node ◦ Posterior wall of the left ventricle ◦ Perfuses ◦ Back of septum Image Source: John Hopkins Image Source: Stanford Health ◦ Right atrium and ventricle Bottom of both ventricles and back of the septum ◦ SA and AV node ◦ Bundle of His and Posterior Descending Artery (PDA) ◦ 15 16 Cardiac Anatomy & Physiology – Cardiac Cell Properties Cardiac Anatomy & Physiology – Cardiac Cell Properties Cardiac cells are responsible for the heart’s electrical and mechanical activity Four main cardiac cell characteristics 1. Automaticity : heart’s ability to generate its own electrical impulse There are 2 types of cardiac cells 2. Contractility : heart’s response to electrical stimulation in order to eject blood from the heart 3. Excitability : heart’s ability to react to and change the rate of contraction in response to additional or external Myocardial Cells stimuli ◦ Form the muscular layer of the atrial and ventricular walls 4. Conductivity : heart’s ability to transmit electrical impulses from cell to cell ◦ Primary Function : contraction and relaxation Pacemaker Cells ◦ Found in nodes , bundles, and branching networks in the heart ◦ Primary Function : conduction of electrical activity 17 18 3