PSIO 202, Lecture 5

PSIO 202, Lecture 5 - PSIO 202 PSIO Human Anatomy and...

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Unformatted text preview: PSIO 202 PSIO Human Anatomy and Physiology Lecture 5 The Heart: Gross Anatomy Objectives and Reading Assignment Reading: Tortora, pages 717-730 Objectives Describe the location and surface anatomic features of the heart Compare and contrast the two major circulatory systems in the human body Diagram, without reference to your notes or book, the path of blood flow through the heart and lungs Identify the major blood vessels, chambers and valves of the heart Diagram the coronary arteries, and discuss what parts of the heart muscle that each supplies Historical Overview and Background In 1628 William Harvey hypothesized that blood flows circulates In the late 17th century Marcello Malphighi observed capillaries through his microscope The circulatory system is often described as a “tree” Blood vessels are arranged in parallel Systemic Circulation carries oxygenated blood from the aorta to the tissues the left ventricle ejects blood into the aorta The blood is distributed to 6 major organ systems: brain, heart, kidneys, muscle, GI system, and skin The Pulmonary Circulation the pulmonary circulation carries deoxygenated blood (venous blood) to the lungs and then back to the heart the right ventricle ejects blood into the pulmonary circulation blood leaving the pulmonary circuit (arterial blood) enters the left atrium Pathway of Blood through the Heart and Lungs Pathway The Cardiac Output the amount of blood pumped by the ventricles per unit time under resting conditions, the left and right ventricles each pump about 5 liters of blood per minute this value can be increased to as much as 30 liters per minute during maximal exercise Superficial Anatomy of the Heart the heart is located behind the sternum, above the diaphragm 2/3 of the mass lies left of midline, and the apex points down and to the left. the heart is about 5 inches long, 3.5 inches wide and 2.5 inches thick the great vessels that emerge from the heart include the pulmonary arteries and veins, the aorta, and the superior and inferior vena cava. Heart Anatomy Heart Heart Covering Pericardial anatomy Fibrous pericardium Serous pericardium (separated by pericardial cavity) Epicardium (visceral layer) Figure 17.2 Heart Covering Pericardial physiology Protects and anchors heart Prevents overfilling Figure 17.2 Heart Wall Epicardium – visceral layer of the serous pericardium Myocardium – cardiac muscle layer forming the bulk of the heart Fibrous skeleton of the heart – crisscrossing, interlacing layer of connective tissue Endocardium – endothelial layer of the inner myocardial surface Anterior Surface Anatomy of the Heart Posterior Surface Anatomy of the Heart Chambers of the Heart The mammalian heart is composed of four chambers the right atrium the left atrium the right ventricle the left ventricle • the left ventricle has much more muscle and is much thicker than the right ventricle Superior View of Ventricles Sagittal View of Heart Chambers, Showing the Valves Heart Valves the heart has four “one-way” valves The valves insure that the blood flows in one direction, from heart to tissues and back to the heart two atrioventricular valves (between atria and ventricles) two semilunar valves (between LV and aorta and between RV and pulmonary trunk) Atrioventricular Valves the left AV valve is also called the bicuspid or mitral valve, and separates the left atrium and left ventricle the right AV valve is also called the tricuspid valve, and separates the right atrium and right ventricle Atrioventricular Valves, Con’t. the tissue flaps of the AV valves have tendons know as chordae tendinae. these tendons attach the valve cusps to the inner ventricular walls they prevent “prolapse” of the valves into the atria during ventricular contraction specialized muscles, known as papillary muscles, regulate tension in the chordae tendinae, and contract simultaneously with the ventricles AV Valves Figure 17.10 Semilunar Valves The aortic semilunar valve separates the left ventricular chamber from the aorta the pulmonary semilunar valve separates the right ventricular chamber from the main pulmonary trunk these valves are pressure dependent, meaning that they open and close in response to pressure differences in the vessels and ventricular chambers Heart Valves Figure 17.9 Pressure-dependent Valve Function Aortic Pressure = 100 mmHg Aortic Pressure = 100 mmHg VentricularPressure = 95 mmHG; Valve cannot open Ventricular Pressure = 101 mmHG; valves open and blood is ejected Coronary Circulation Coronary circulation is the functional blood supply to the heart Collateral routes insure blood delivery to heart even if major vessels are occluded Blood Supply to Heart Muscle Tissue the tissues of the heart are supplied with blood from the right and left coronary arteries the right coronary artery originates on the ascending aorta the left coronary artery also originates on the ascending aorta Coronary Circulation originates on the ascending aorta supplies the SA node, the AV node, parts of the right atrium, the interventricular septum, the right ventricle and the left ventricle the marginal branch originates on the right coronary and supplies the anterior portions of the right ventricle the posterior interventricular branch originates on the right coronary and supplies the posterior portions of both ventricles The Right Coronary Artery The Left Coronary Artery originates on the ascending aorta supplies the SA node, and parts of the left atrium, interventricular septum, and ventricles the circumflex branch supplies the left atrium and posterior regions of the left ventricle the anterior interventricular branch originates from the left coronary and supplies the anterior portions of both ventricles Coronary Circulation: Veins •Great cardiac drains the anterior heart •Middle cardiac vein drains the posterior heart •Both drain into the coronary sinus which, in turn, drains into the right atrium ...
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