Cardio_1-heart anatomy3.pdf

Cardiovascular System Learning Objectives: Cardiovascular System 1 (CV1) General functions of the cardiovascular system Describe the functions of a circulatory system and list the major substances transported by the human cardiovascular system. Compare and c...

Cardiovascular System Learning Objectives: Cardiovascular System 1 (CV1) General functions of the cardiovascular system Describe the functions of a circulatory system and list the major substances transported by the human cardiovascular system. Compare and contrast the systemic and pulmonary circuits (circulations) with respect to structure and function Describe the basic structure and function(s) of the heart Trace a drop of blood from the right atrium through the cardiovascular system until it returns to the right atrium, listing all significant anatomical structures the drop of blood encounters along the way. © 2016 Pearson Education, Ltd.  18.1 Heart Anatomy The Pulmonary and Systemic Circuits Heart is a transport system consisting of two side-by-side pumps – Right side receives oxygen-poor blood from tissues Pumps blood to lungs to get rid of CO2, pick up O2, via pulmonary circuit – Left side receives oxygenated blood from lungs Pumps blood to body tissues via systemic circuit © 2016 Pearson Education, Ltd.  The Pulmonary and Systemic Circuits (cont.) Receiving chambers of heart – Right atrium Receives blood returning from systemic circuit – Left atrium Receives blood returning from pulmonary circuit Pumping chambers of heart – Right ventricle Pumps blood through pulmonary circuit – Left ventricle Pumps blood through systemic circuit © 2016 Pearson Education, Ltd. Figure 18.1 The systemic and pulmonary circuits. Capillary beds of lungs where gas exchange occurs Pulmonary Circuit Pulmonary Pulmonary arteries veins Aorta and Venae branches cavae Left atrium Left Right ventricle atrium Right Heart ventricle Systemic Circuit Capillary beds Oxygen-rich, of all body CO2-poor blood tissues where gas Oxygen-poor, exchange occurs CO2-rich blood © 2016 Pearson Education, Ltd.  Coverings of the Heart Pericardium: double-walled sac that surrounds heart; made up of two layers 1. Superficial fibrous pericardium: functions to protect, anchor heart to surrounding structures, and prevent overfilling 2. Deep two-layered serous pericardium Parietal layer lines internal surface of fibrous pericardium Visceral layer (epicardium) on external surface of heart Two layers separated by fluid-filled pericardial cavity (decreases friction) 3. Epicardium: visceral layer of serous pericardium 4. Myocardium: circular or spiral bundles of contractile cardiac muscle cells Cardiac skeleton: crisscrossing, interlacing layer of connective tissue – Anchors cardiac muscle fibers – Supports great vessels and valves – Limits spread of action potentials to specific paths © 2016 Pearson Education, Ltd. Figure 18.3 The layers of the pericardium and of the heart wall. Pulmonary trunk Fibrous pericardium Parietal layer of serous Pericardium pericardium Myocardium Pericardial cavity Epicardium (visceral layer of serous Heart pericardium) wall Myocardium Endocardium Heart chamber © 2016 Pearson Education, Ltd.  Clinical – Homeostatic Imbalance 18.1 Pericarditis – Inflammation of pericardium – Roughens membrane surfaces, causing pericardial friction rub (creaking sound) heard with stethoscope – Cardiac tamponade Excess fluid that leaks into pericardial space Can compress heart’s pumping ability Treatment: fluid is drawn out of cavity (usually with syringe) © 2016 Pearson Education, Ltd. Figure 18.5e Gross anatomy of the heart. Aorta Left pulmonary artery Superior vena cava Left atrium Right pulmonary artery Left pulmonary veins Pulmonary trunk Right atrium Mitral (bicuspid) valve Right pulmonary veins Fossa ovalis Aortic valve Pectinate muscles Pulmonary valve Tricuspid valve Right ventricle Left ventricle Chordae tendineae Papillary muscle Interventricular septum Trabeculae carneae Epicardium Inferior vena cava Myocardium Endocardium Frontal section © 2016 Pearson Education, Ltd. Figure 18.5b Gross anatomy of the heart. Left common carotid Brachiocephalic trunk artery Left subclavian artery Superior vena cava Aortic arch Ligamentum arteriosum Right pulmonary artery Left pulmonary artery Ascending aorta Left pulmonary veins Pulmonary trunk Auricle of left atrium Right pulmonary veins Circumflex artery Right atrium Right coronary artery Left coronary artery (in coronary sulcus) (in coronary sulcus) Anterior cardiac vein Left ventricle Right ventricle Right marginal artery Great cardiac vein Small cardiac vein Anterior interventricular artery (in anterior interventricular sulcus) Inferior vena cava Apex Anterior view © 2016 Pearson Education, Ltd.  Chambers and Associated Great Vessels Four chambers of the heart Atria: the receiving chambers – Small, thin-walled chambers; contribute little to propulsion of blood – Auricles: appendages that increase atrial volume – Right atrium: receives deoxygenated blood from body Three veins empty into right atrium: – Superior vena cava: returns blood from body regions above the diaphragm – Inferior vena cava: returns blood from body regions below the diaphragm – Coronary sinus: returns blood from coronary veins – Left atrium: receives oxygenated blood from lungs Pectinate muscles found only in auricles Four pulmonary veins return blood from lungs © 2016 Pearson Education, Ltd.  Chambers and Associated Great Vessels (cont.) Ventricles: the discharging chambers – Make up most of the volume of heart – Thicker walls than atria – Actual pumps of heart – Right ventricle Pumps blood into pulmonary trunk – Left ventricle Pumps blood into aorta (largest artery in body) © 2016 Pearson Education, Ltd.  18.2 Heart Valves Ensure unidirectional blood flow through heart Open and close in response to pressure changes Two major types of valves – Atrioventricular valves located between atria and ventricles – Semilunar valves located between ventricles and major arteries © 2016 Pearson Education, Ltd.  Atrioventricular (AV) Valves Two atrioventricular (AV) valves prevent backflow into atria when ventricles contract – Tricuspid valve (right AV valve): made up of three cusps and lies between right atria and ventricle – Mitral valve (left AV valve, bicuspid valve): made up of two cusps and lies between left atria and ventricle – Chordae tendineae: anchor cusps of AV valves to papillary muscles that function to: Hold valve flaps in closed position Prevent flaps from everting back into atria 1 Blood returning to the Direction of heart fills atria, pressing blood flow against the AV valves. The increased pressure forces Atrium AV valves open. Cusp of 2 As ventricles fill, AV valve atrioventricular flaps hang limply into ventricles. valve (open) Chordae tendineae 3 Atria contract, forcing additional blood into ventricles. Papillary Ventricle muscle AV valves © 2016 Pearson open; Education, Ltd. atrial pressure greater than ventricular pressure  Semilunar (SL) valves Two semilunar (SL) valves prevent backflow from major arteries back into ventricles – Open and close in response to pressure changes – Each valve consists of three cusps that roughly resemble a half moon – Pulmonary semilunar valve: located between right ventricle and pulmonary trunk – Aortic semilunar valve: located between left ventricle and aorta © 2016 Pearson Education, Ltd.  Semilunar (SL) valves © 2016 Pearson Education, Ltd.  Clinical – Homeostatic Imbalance 18.2 Two conditions severely weaken heart: – Incompetent valve Blood backflows so heart repumps same blood over and over – Valvular stenosis Stiff flaps that constrict opening Heart needs to exert more force to pump blood Defective valve can be replaced with mechanical, animal, or cadaver valve © 2016 Pearson Education, Ltd.  18.3 Pathway of Blood Through Heart Right side of the heart – Superior vena cava (SVC), inferior vena cava (IVC), and coronary sinus → – Right atrium → – Tricuspid valve → – Right ventricle → – Pulmonary semilunar valve → – Pulmonary trunk → – Pulmonary arteries → – Lungs © 2016 Pearson Education, Ltd.  18.3 Pathway of Blood Through Heart Left side of the heart – Four pulmonary veins → – Left atrium → – Mitral valve → – Left ventricle → – Aortic semilunar valve → – Aorta → – Systemic circulation © 2016 Pearson Education, Ltd. Focus Figure 18.1 The heart is a double pump, each side supplying its own circuit. Tricuspid Pulmonary Oxygen-poor blood Superior vena cava (SVC) Right valve Right semilunar valve Pulmonary Oxygen-rich blood Inferior vena cava (IVC) atrium ventricle trunk Coronary sinus Pulmonary arteries SVC Coronary sinus Pulmonary trunk Right Tricuspid atrium Pulmonary valve semilunar valve Right IVC ventricle Oxygen-poor blood is carried Oxygen-poor blood in two pulmonary arteries to To heart returns from the body the lungs (pulmonary circuit) To lungs tissues back to the heart. to be oxygenated. Systemic Pulmonary capillaries capillaries Oxygen-rich blood is Oxygen-rich blood To body delivered to the body returns to the heart via To heart tissues (systemic circuit). the four pulmonary veins. Aorta Pulmonary veins Aortic Left semilunar Mitral valve atrium valve Left ventricle Aortic Mitral semilunar valve Left valve Left Four Aorta ventricle atrium pulmonary veins © 2016 Pearson Education, Ltd.  18.3 Pathway of Blood Through Heart Equal volumes of blood are pumped to pulmonary and systemic circuits Pulmonary circuit is short, low-pressure circulation Systemic circuit is long, high-friction circulation Anatomy of ventricles reflects differences – Left ventricle walls are 3× thicker than right Pumps with greater pressure © 2016 Pearson Education, Ltd.  Coronary Circulation Coronary circulation – Functional blood supply to heart muscle itself – Shortest circulation in body – Delivered when heart is relaxed – Left ventricle receives most of coronary blood supply Coronary arteries – Both left and right coronary arteries arise from base of aorta and supply arterial blood to heart – Both encircle heart in coronary sulcus – Branching of coronary arteries varies among individuals – Arteries contain many anastomoses (junctions) Provide additional routes for blood delivery Cannot compensate for coronary artery occlusion – Heart receives 1/20th of body’s blood supply © 2016 Pearson Education, Ltd.  Clinical – Homeostatic Imbalance 18.3 Angina pectoris – Thoracic pain caused by fleeting deficiency in blood delivery to myocardium – Cells are weakened Myocardial infarction (heart attack) – Prolonged coronary blockage – Areas of cell death are repaired with noncontractile scar tissue © 2016 Pearson Education, Ltd.