Anatomy & Physiology Chapter 17 Part A: The Cardiovascular System: The Heart PDF

Anatomy & Physiology Seventh Edition Chapter 17 Part A The Cardiovascular System: The Heart PowerPoint® Lectures Slides...

Anatomy & Physiology Seventh Edition Chapter 17 Part A The Cardiovascular System: The Heart PowerPoint® Lectures Slides prepared by Karen Dunbar Kareiva, Ivy Tech Community College Copyright © 2020 Pearson Education, Inc. All Rights Reserved The Pulmonary and Systemic Circuits (1 of 2) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved The Pulmonary and Systemic Circuits (2 of 2) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.1 The Systemic and Pulmonary Circuits Copyright © 2020 Pearson Education, Inc. All Rights Reserved Size, Location, and Orientation of Heart (1 of 2) Approximately the size of a fist – Weighs less than 1 pound Location – In mediastinum between second rib and fifth intercostal space – On superior surface of diaphragm – Two-thirds of heart to left of midsternal line – Anterior to vertebral column, posterior to sternum Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.2a Location of the Heart in Mediastinum Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.2b Location of the Heart in Mediastinum Copyright © 2020 Pearson Education, Inc. All Rights Reserved Size, Location, and Orientation of Heart (2 of 2) Base (posterior surface) leans toward the right shoulder Apex points toward the left hip Apical impulse palpated between fifth and sixth ribs, just below the left nipple Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.2c Location of the Heart in Mediastinum Copyright © 2020 Pearson Education, Inc. All Rights Reserved Coverings of the Heart Pericardium: double-walled sac that surrounds heart; made up of two layers – Superficial fibrous pericardium: functions to protect, anchor heart to surrounding structures, and prevent overfilling – 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) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.3 The Layers of the Pericardium and of the Heart Wall (1 of 2) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Clinical—Homeostatic Imbalance 17.1 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) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Layers of the Heart Wall (1 of 2) Three layers of heart wall – Epicardium: visceral layer of serous pericardium – 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.4 The Circular and Spiral Arrangement of Cardiac Muscle Bundles in the Myocardium of the Heart Copyright © 2020 Pearson Education, Inc. All Rights Reserved Layers of the Heart Wall (2 of 2) – Endocardium: innermost layer; is continuous with endothelial lining of blood vessels ▪ Lines heart chambers and covers cardiac skeleton of valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.3 The Layers of the Pericardium and of the Heart Wall (2 of 2) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Chambers and Associated Great Vessels (1 of 6) Internal features – Four chambers ▪ Two superior atria ▪ Two inferior ventricles – Interatrial septum: separates atria ▪ Fossa ovalis: remnant of foramen ovale of fetal heart – Interventricular septum: separates ventricles Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5e Gross Anatomy of the Heart (1 of 3) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Chambers and Associated Great Vessels (2 of 6) Surface features – Coronary sulcus (atrioventricular groove) ▪ Encircles junction of atria and ventricles – Anterior interventricular sulcus ▪ Anterior position of interventricular septum – Posterior interventricular sulcus ▪ Landmark on posteroinferior surface Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5b Gross Anatomy of the Heart Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5d Gross Anatomy of the Heart (1 of 2) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Chambers and Associated Great Vessels (3 of 6) 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 ▪ Anterior portion is smooth-walled ▪ Posterior portion contains ridges formed by pectinate muscles ▪ Posterior and anterior regions are separated by crista terminalis Copyright © 2020 Pearson Education, Inc. All Rights Reserved Chambers and Associated Great Vessels (4 of 6) Atria: the receiving chambers – 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5e Gross Anatomy of the Heart (2 of 3) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Chambers and Associated Great Vessels (5 of 6) Ventricles: the discharging chambers – Make up most of the volume of heart – Right ventricle: most of anterior surface – Left ventricle: posteroinferior surface – Trabeculae carneae: irregular ridges of muscle on ventricular walls – Papillary muscles: project into ventricular cavity ▪ Anchor chordae tendineae that are attached to heart valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Chambers and Associated Great Vessels (6 of 6) Ventricles: the discharging chambers – 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) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5e Gross Anatomy of the Heart (3 of 3) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5c Gross Anatomy of the Heart Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5f Gross Anatomy of the Heart Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5a Gross Anatomy of the Heart Copyright © 2020 Pearson Education, Inc. All Rights Reserved 17.2 Heart Valves (1 of 2) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved 17.2 Heart Valves (2 of 2) No valves are found between major veins and atria; not a problem because: – Inertia of incoming blood prevents backflow – Heart contractions compress venous openings Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.6a-b Heart Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.6c-d Heart Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.7a The Function of the Atrioventricular (AV) Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.7b The Function of the Atrioventricular (AV) Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.6a Heart Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.8a The Function of the Semilunar (SL) Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.8b The Function of the Semilunar (SL) Valves Copyright © 2020 Pearson Education, Inc. All Rights Reserved Clinical—Homeostatic Imbalance 17.2 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved 17.3 Pathway of Blood Through the Heart (1 of 3) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved 17.3 Pathway of Blood Through the Heart (2 of 3) Left side of the heart – Four pulmonary veins → – Left atrium → – Mitral valve → – Left ventricle → – Aortic semilunar valve → – Aorta → – Systemic circulation Copyright © 2020 Pearson Education, Inc. All Rights Reserved Copyright © 2020 Pearson Education, Inc. All Rights Reserved 17.3 Pathway of Blood Through the Heart (3 of 3) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.9 Anatomical Differences Between the Right and Left Ventricles Copyright © 2020 Pearson Education, Inc. All Rights Reserved Coronary Circulation (1 of 4) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Coronary Circulation (2 of 4) 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Coronary Circulation (3 of 4) Coronary arteries – Left coronary artery supplies interventricular septum, anterior ventricular walls, left atrium, and posterior wall of left ventricle; has two branches: ▪ Anterior interventricular artery ▪ Circumflex artery – Right coronary artery supplies right atrium and most of right ventricle; has two branches: ▪ Right marginal artery ▪ Posterior interventricular artery Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.10a Coronary Circulation Copyright © 2020 Pearson Education, Inc. All Rights Reserved Coronary Circulation (4 of 4) Coronary veins – Cardiac veins collect blood from capillary beds – Coronary sinus empties into the right atrium; formed by merging cardiac veins ▪ Great cardiac vein of anterior interventricular sulcus ▪ Middle cardiac vein in posterior interventricular sulcus ▪ Small cardiac vein from inferior margin – Several anterior cardiac veins empty directly into right atrium anteriorly Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.10b Coronary Circulation Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.5d Gross Anatomy of the Heart (2 of 2) Copyright © 2020 Pearson Education, Inc. All Rights Reserved Clinical—Homeostatic Imbalance 17.3 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 Copyright © 2020 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy (1 of 3) Cardiac muscle cells: striated, short, branched, fat, interconnected – One central nucleus (at most, 2 nuclei) – Contain numerous large mitochondria (25–35% of cell volume) that afford resistance to fatigue – Rest of volume composed of sarcomeres ▪ Z discs, A bands, and I bands all present – T tubules are wider, but less numerous ▪ Enter cell only once at Z disc – SR simpler than in skeletal muscle; no triads Copyright © 2020 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy (2 of 3) Intercalated discs are connecting junctions between cardiac cells that contain: – Desmosomes: hold cells together; prevent cells from separating during contraction – Gap junctions: allow ions to pass from cell to cell; electrically couple adjacent cells ▪ Allows heart to be a functional syncytium, a single coordinated unit Copyright © 2020 Pearson Education, Inc. All Rights Reserved Microscopic Anatomy (3 of 3) Intercellular space between cells has connective tissue matrix (endomysium) – Contains numerous capillaries – Connects cardiac muscle to cardiac skeleton, giving cells something to pull against Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.11a Microscopic Anatomy of Cardiac Muscle Copyright © 2020 Pearson Education, Inc. All Rights Reserved Figure 17.11b Microscopic Anatomy of Cardiac Muscle Copyright © 2020 Pearson Education, Inc. All Rights Reserved How Does the Physiology of Skeletal and Cardiac Muscle Differ? (1 of 5) Similarities with skeletal muscle – Muscle contraction is preceded by depolarizing action potential – Depolarization wave travels down T tubules; causes sarcoplasmic reticulum (SR) to release Ca2+ – Excitation-contraction coupling occurs ▪ Ca2+ binds troponin causing filaments to slide Copyright © 2020 Pearson Education, Inc. All Rights Reserved How Does the Physiology of Skeletal and Cardiac Muscle Differ? (2 of 5) Differences between cardiac and skeletal muscle – Some cardiac muscle cells are self-excitable ▪ Two kinds of myocytes – Contractile cells: responsible for contraction – Pacemaker cells: noncontractile cells that spontaneously depolarize Initiate depolarization of entire heart Do not need nervous system stimulation, in contrast to skeletal muscle fibers Copyright © 2020 Pearson Education, Inc. All Rights Reserved How Does the Physiology of Skeletal and Cardiac Muscle Differ? (3 of 5) – Heart contracts as a unit ▪ All cardiomyocytes contract as unit (functional syncytium), or none contract ▪ Contraction of all cardiac myocytes ensures effective pumping action ▪ Skeletal muscles contract independently – Influx of Ca2+ from extracellular fluid triggers Ca2+ release from SR ▪ Depolarization opens slow Ca2+ channels in sarcolemma, allowing Ca2+ to enter cell ▪ Extracellular Ca2+ then causes SR to release its intracellular Ca2+ ▪ Skeletal muscles do not use extracellular Ca2+ Copyright © 2020 Pearson Education, Inc. All Rights Reserved How Does the Physiology of Skeletal and Cardiac Muscle Differ? (4 of 5) – Tetanic contractions cannot occur in cardiac muscles ▪ Cardiac muscle fibers have longer absolute refractory period than skeletal muscle fibers – Absolute refractory period is almost as long as contraction itself – Prevents tetanic contractions – Allows heart to relax and fill as needed to be an efficient pump Copyright © 2020 Pearson Education, Inc. All Rights Reserved How Does the Physiology of Skeletal and Cardiac Muscle Differ? (5 of 5) – The heart relies almost exclusively on aerobic respiration ▪ Cardiac muscle has more mitochondria than skeletal muscle so has greater dependence on oxygen – Cannot function without oxygen ▪ Skeletal muscle can go through fermentation when oxygen not present ▪ Both types of tissues can use other fuel sources – Cardiac is more adaptable to other fuels, including lactic acid, but must have oxygen Copyright © 2020 Pearson Education, Inc. All Rights Reserved Table 17.1 Key Differences between Skeletal and Cardiac Muscle Copyright © 2020 Pearson Education, Inc. All Rights Reserved