Cardiovascular System - Human Anatomy & Physiology - PDF

Human Anatomy & Physiology II (PSIO202) The Cardiovascular System  Objectives 1. Describe the location and the important anatomical features of the heart. 2. Compare and contrast the two major circulatory systems in the human body. 3. Diagram, without...

Human Anatomy & Physiology II (PSIO202) The Cardiovascular System  Objectives 1. Describe the location and the important anatomical features of the heart. 2. Compare and contrast the two major circulatory systems in the human body. 3. Diagram, without reference to your notes or book, the path of blood flow through the heart and lungs. 4. Identify the major blood vessels, chambers and valves of the heart. 5. Diagram the coronary arteries, and discuss which parts of the heart muscle each artery supplies.  The Cardiovascular System The cardiovascular system has three components: 1. The Heart which acts as a pump to propel… 2. Blood which moves through tubes called… which conduct 3. Blood blood throughout Vessels the body.  The Circulation of Blood (Cardiovascular Circulation) Circulation is continuous. The heart is a double pump; blood makes two trips through the heart before returning to where it started. Each stop at the heart is the end of a separate circuit (heart → arteries → capillaries → veins → heart). There are two cardiovascular circuits: 1. Systemic circuit (aka “Systemic Circulation”) carries oxygen & nutrients to the cells of our body. 2. Pulmonary circuit (aka “Pulmonary Circulation”) reloads blood with oxygen.  The Systemic Circuit (Systemic Circulation) carries oxygenated blood (“arterial blood”) to body cells/tissues/organs. begins with the left ventricle of the heart (ejects blood into the aorta) and ends with the right atrium (collects returning blood). distributes blood in a parallel manner. Major recipients of blood include: kidneys, GI system, skeletal muscle, brain, skin, liver, bone, and heart (in proportionally descending order).  The Pulmonary Circuit (Pulmonary Circulation) carries de‐oxygenated blood (“venous blood”) to the lungs where it is reloaded with oxygen (and emptied of excess carbon dioxide) before returning to the heart. begins with the right ventricle of the heart (ejects blood into the pulmonary trunk) and ends with the left atrium (collects the returning blood). requires proper functioning of the respiratory system. The Circulation of Blood (Cardiovascular Circulation)  The Cardiac Output (CO) is the amount of blood pumped by a ventricle per unit time (measured in L/min). is the same for both systemic & pulmonary circuits (right & left ventricles eject same amount of blood). is equal to about 5 L/min under resting conditions. O2 CO2 changes to meet the needs of the body. CO can be increased to as much as 30 L/min during maximal exercise.  The Heart is composed primarily of cardiac muscle is a (double) pump contains 4 chambers directs blood flow by means of 4 valves is supplied with blood by the first two arteries formed off of the aorta  Chambers of the Heart The mammalian heart is composed of four chambers: 1. the right atrium (RA) 2. the left atrium (LA) 3. the right ventricle (RV) 4. the left ventricle (LV) The atria receive blood; the ventricles force blood out of the heart into systemic & pulmonary circuits. Due to differences in workload, the left ventricle has much more muscle (is much thicker) than the right ventricle. Cross‐Section of the Ventricles of the Heart Blood Flow through the Heart Chambers Aorta Left Atrium Right Atrium Left Ventricle Why does blood move in only one direction? Right Ventricle (always into the atria, then the ventricles, then out of the heart?)  Heart Valves! There are four “one‐way” heart valves. Heart valves ensure that blood flows through the heart in only one direction. 2 atrioventricular valves (between each set of atria & ventricles (i.e., between RA&RV, and LA&LV) 2 semilunar valves (one between LV & aorta, and the other between RV & pulmonary trunk).  Atrioventricular (AV) Valves left AV valve = bicuspid valve (“two cusps”) Aorta bicuspid = mitral valve valve Left separates left atrium & Atrium left ventricle Right Atrium right AV valve Left Ventricle = tricuspid valve (“three cusps”) Right separates right atrium & Ventricle right ventricle tricuspid valve  Atrioventricular (AV) Valves The tissue flaps of the AV valves have tendons known as chordae tendinae – chordae tendinae attach the valve cusps to the inner ventricular walls – chordae tendinae 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 Atrioventricular (AV) Valves  Semilunar Valves The aortic semilunar valve separates the left ventricular chamber from the aorta right semilunar the pulmonary semilunar valve valve separates the right ventricular Aorta chamber from the pulmonary trunk Left like the AV valves, these valves Atrium open in a pressure‐dependent manner, meaning that they open Right Atrium and close in response to pressure Left differences between the major Ventricle vessels and the heart ventricles Right Ventricle aortic semilunar left semilunar valve (superior view) valve  Pressure‐Dependent Valve Function Aortic Pressure Aortic Pressure = 100 mmHg = 100 mmHg Ventricular Pressure = 95 mmHg; Ventricular Pressure = 101 mmHg; Valve cannot open valves open and blood is ejected  Coordination of Heart Valve Function AV valves open & close together Semilunar valves open & close together  Summary of Pulmonary circulation CV Circulation Systemic circulation Summary of Important Internal Anatomical Features of the Heart (a) Anterior view of frontal section showing internal anatomy  Coronary Circulation: Arteries Coronary circulation is the part of systemic circulation that provides the heart tissue itself with blood. Collateral routes (anastomoses) ensure blood delivery to heart tissue even if major vessels are occluded.  Coronary Circulation: Arteries the tissues of the heart RIGHT CORONARY LEFT are supplied with blood ARTERY CORONARY from the right and left ARTERY coronary arteries right coronary artery originates on the ascending aorta left coronary artery also originates on the ascending aorta  Originates on ascending aorta Right Coronary Artery Supplies SA node, AV node, parts of RA, interventricular septum, & both ventricles – Marginal Branch originates on right coronary; supplies anterior portions of right ventricle – Posterior Interventricular Branch originates on right coronary; supplies posterior portions of both ventricles RIGHT CORONARY ARTERY MARGINAL BRANCH POSTERIOR INTERVENTRICULAR BRANCH  Left Coronary Artery Originates on left ascending aorta Supplies SA node, left atrium, interventricular LEFT septum, and both ventricles CORONARY – Circumflex Branch supplies left atrium & ARTERY posterior regions of left ventricle – Anterior Interventricular Branch supplies anterior portions of both ventricles ANTERIOR INTERVENTRICULAR CIRCUMFLEX BRANCH BRANCH  Coronary Circulation: Veins Great cardiac vein drains CORONARY the anterior heart SINUS Middle cardiac vein MIDDLE drains the posterior CARDIAC VEIN heart Both drain into the coronary sinus which, in turn, drains into the right Vena Cava to atrium right atrium