Heart Lecture Outline PDF

1 Chapter 12 Heart Lecture Outline © 2019 McGraw-Hill Education  2 The Cardiovascular System 1...

1 Chapter 12 Heart Lecture Outline © 2019 McGraw-Hill Education  2 The Cardiovascular System 1 The heart is a muscular organ that is essential for life because it pumps blood through the body. The heart is a member organ of the cardiovascular system, which consists of the heart, blood vessels, and blood. The heart of a healthy adult, at rest, pumps approximately 5 liters (L) of blood per minute. For most people, the heart continues to pump at approximately that rate for more than 75 years. © 2019 McGraw-Hill Education  3 The Cardiovascular System 2 Figure 12.1 © 2019 McGraw-Hill Education  4 The Cardiovascular System 3 The heart is a member organ of the cardiovascular system, which consists of the heart, blood vessels, and blood. The heart is actually two pumps in one, with the heart’s right side pumping to the lungs and back to the left side of the heart through vessels of the pulmonary circulation. The left side of the heart pumps blood to all other tissues of the body and back to the right side of the heart through vessels of the systemic circulation. © 2019 McGraw-Hill Education  5 The Circulatory System Figure 12.2 © 2019 McGraw-Hill Education  6 Functions of the Heart 1. Generates blood pressure 2. Routes blood 3. Ensures one-way blood flow 4. Regulates blood supply © 2019 McGraw-Hill Education  7 Heart Characteristics Size: size of a fist and weighs less than 1 lb. Location: between lungs in thoracic cavity Orientation: apex (bottom) towards left side Figure 12.3 © 2019 McGraw-Hill Education  8 Pericardia Pericardium: double-layered sac that anchors and protects heart Parietal pericardium: membrane around heart’s cavity Visceral pericardium: membrane on heart’s surface Pericardial cavity: space around heart Figure 12.4 © 2019 McGraw-Hill Education  9 Heart External Anatomy 1 A coronary sulcus extends around the heart, separating the atria from the ventricles. Two grooves, or sulci, which indicate the division between the right and left ventricles, extend inferiorly from the coronary sulcus. The anterior interventricular sulcus extends inferiorly from the coronary sulcus on the anterior surface of the heart. © 2019 McGraw-Hill Education  10 Heart External Anatomy 2 The posterior interventricular sulcus extends inferiorly from the coronary sulcus on the posterior surface of the heart. The superior vena cava and inferior vena cava carry blood from the body to the right atrium, and four pulmonary veins carry blood from the lungs to the left atrium. Two arteries, often called the great vessels or great arteries, carry blood away from the ventricles of the heart. © 2019 McGraw-Hill Education  11 Heart External Anatomy 3 The pulmonary trunk, arising from the right ventricle, splits into the right and left pulmonary arteries, which carry blood to the lungs. The aorta arising from the left ventricle, carries blood to the rest of the body. © 2019 McGraw-Hill Education  12 Surface Anatomy of the Heart 1 Figure 12.5a © 2019 McGraw-Hill Education  13 Surface Anatomy of the Heart 2 Figure 12.5c © 2019 McGraw-Hill Education  14 Heart Chambers Four Chambers: left atrium (LA) right atrium (RA) left ventricle (LV) right ventricle (RV) Coronary sulcus: separates atria from ventricles © 2019 McGraw-Hill Education  15 The Atria Superior chambers Holding chambers Small, thin walled Contract minimally to push blood into ventricles Interatrial septum: separates right and left atria © 2019 McGraw-Hill Education  16 Ventricles Inferior chambers Pumping chambers Thick, strong walled Contract forcefully to propel blood out of heart Interventricular septum: separates right and left ventricles © 2019 McGraw-Hill Education  17 Atrioventricular Heart Valves Valves between the atria and ventricles Tricuspid valve: AV valve between RA and RV 3 cusps Bicuspid valve (mitral): AV valve between LA and LV 2 cusps © 2019 McGraw-Hill Education  18 Valvular Control Each ventricle contains cone-shaped, muscular pillars called papillary muscles. These muscles are attached by strong, connective tissue strings called chordae tendineae to the free margins of the cusps of the atrioventricular valves. When the ventricles contract, the papillary muscles contract and prevent the valves from opening into the atria by pulling on the chordae tendineae attached to the valve cusps. © 2019 McGraw-Hill Education  19 Semilunar Heart Valves The semilunar valves have three half-moon shaped cusps, and are valves between the pulmonary trunk and aorta. Pulmonary valve: between RV and pulmonary trunk Aortic valve: between LV and aorta © 2019 McGraw-Hill Education  20 Internal Anatomy of the Heart Figure 12.6 © 2019 McGraw-Hill Education  21 Heart Valves 1 Figure 12.7 © 2019 McGraw-Hill Education (a) ©VideoSurgery/Science Source; (b) ©Oktay Ortakcioglu/iStock/360/Getty Images RF  22 Heart Valves 2 Figure 12.8 © 2019 McGraw-Hill Education  23 Cardiac Skeleton 1 A plate of connective tissue, sometimes called the cardiac skeleton, or fibrous skeleton, consists mainly of fibrous rings that surround the atrioventricular and semilunar valves and give them solid support. This connective tissue plate also serves as electrical insulation between the atria and the ventricles and provides a rigid attachment site for cardiac muscle. © 2019 McGraw-Hill Education  24 Cardiac Skeleton 2 Figure 12.9 © 2019 McGraw-Hill Education  25 Blood Flow through Heart 1 1. RA 2. Tricuspid valve 3. RV 4. Pulmonary semilunar valve 5. Pulmonary trunk 6. Pulmonary arteries 7. Lungs 8. Pulmonary veins 9. LA 10. Bicuspid valve 11. LV 12. Aortic semilunar valve 13. Aorta 14. Body © 2019 McGraw-Hill Education  26 Blood Flow through Heart 2 Figure 12.10 © 2019 McGraw-Hill Education  27 Blood Supply to the Heart 1 Coronary arteries: supply blood to heart wall originate from base of aorta (above aortic semilunar valve) Left coronary artery: has 3 branches supply blood to anterior heart wall and left ventricle © 2019 McGraw-Hill Education  28 Blood Supply to the Heart 2 Right coronary artery: originates on right side of aorta supply blood to right ventricle Cardiac veins: drain blood from the cardiac muscle parallel to the coronary arteries most drain blood into the coronary sinus from the coronary sinus into the right atrium © 2019 McGraw-Hill Education  29 Blood Supply to the Heart 3 Figure 12.11 © 2019 McGraw-Hill Education  30 Heart Wall Epicardium: surface of heart (outside) Myocardium: thick, middle layer composed of cardiac muscle Endocardium: smooth, inner surface Figure 12.12 © 2019 McGraw-Hill Education  31 Cardiac Muscle 1 centrally located nucleus Branching cells Rich in mitochondria Striated (actin and myosin) Ca2+ and ATP used for contractions Intercalated disks connect cells Figure 12.12 © 2019 McGraw-Hill Education (b) ©Ed Reschke  32 Cardiac Muscle Action Potentials 1 Changes in membrane channels’ permeability are responsible for producing action potentials and is called pacemaker potential. 1. Depolarization phase: Na+ channels open Ca2+ channels open 2. Plateau phase: Na+ channels close Some K+ channels open Ca2+ channels remain open © 2019 McGraw-Hill Education  33 Cardiac Muscle Action Potentials 2 3. Repolarization phase: K+ channels are open Ca2+ channels close Plateau phase prolongs action potential by keeping Ca2+ channels open. In skeletal muscle action potentials take 2 msec, in cardiac muscle they take 200-500 msec. © 2019 McGraw-Hill Education  Action Potentials in Skeletal and 34 Cardiac Muscle Figure 12.14 © 2019 McGraw-Hill Education  35 Conduction System of Heart 1 Contraction of the atria and ventricles is coordinated by specialized cardiac muscle cells in the heart wall that form the conduction system of the heart. All the cells of the conduction system can produce spontaneous action potentials. The conduction system of the heart includes the sinoatrial node, atrioventricular node, atrioventricular bundle, right and left bundle branches, and Purkinje fibers. © 2019 McGraw-Hill Education  36 Conduction System of Heart 2 Sinoatrial node (SA node): in RA where action potential originates functions as pacemaker large number of Ca2+ channels © 2019 McGraw-Hill Education  37 Conduction System of Heart 3 Atrioventricular node (AV node): located in the lower portion of the right atrium action potentials from SA node sent to this node action potentials spread slowly through it slow rate of action potential conduction allows the atria to complete their contraction before action potentials are delivered to the ventricles © 2019 McGraw-Hill Education  38 Conduction System of Heart 4 Atrioventricular bundle: action potentials from AV node travel to AV bundle AV bundle divides into a left and right bundle branches © 2019 McGraw-Hill Education  39 Conduction System of Heart 5 Purkinje Fibers at the tips of the left and right bundle branches, are Purkinje fibers Purkinje fibers pass to the apex of the heart and then extend to the cardiac muscle of the ventricle walls action potentials are rapidly delivered to all the cardiac muscle of the ventricles © 2019 McGraw-Hill Education  40 Action Potential Path through Heart 1. SA node 2. AV node (atrioventricular) 3. AV bundle 4. Right and Left Bundle branches 5. Purkinje fibers © 2019 McGraw-Hill Education  41 Conduction System of the Heart Figure 12.15 © 2019 McGraw-Hill Education  42 Electrocardiogram (EKG) ECG (EKG) record of electrical events in heart diagnoses cardiac abnormalities uses electrodes contains P wave, QRS complex, T wave © 2019 McGraw-Hill Education  43 Components of ECG/EKG P wave: depolarization of atria QRS complex: depolarization of ventricles contains Q, R, S waves T wave: repolarization of ventricles © 2019 McGraw-Hill Education  44 Electrocardiogram Figure 12.16 © 2019 McGraw-Hill Education  45 Cardiac Cycle 1 The cardiac cycle is a summative description of all the events that occur during one single heartbeat. The heart is a two sided pump, with the atria being primers for pumps and the ventricles being the actual pumps. © 2019 McGraw-Hill Education  46 Heart Chamber Contractions Cardiac muscle contractions produce pressure changes within heart chambers. Pressure changes are responsible for blood movement. Blood moves from areas of high to low pressure. © 2019 McGraw-Hill Education  47 Cardiac Cycle 2 Atrial systole: contraction of atria Ventricular systole: contraction of ventricles Atrial diastole: relaxation of atria Ventricular diastole: relaxation of ventricles © 2019 McGraw-Hill Education  48 Cardiac Cycle 3 Figure 12.17 © 2019 McGraw-Hill Education  49 Events of the Cardiac Cycle Figure 12.18 © 2019 McGraw-Hill Education  50 Heart Sounds Heart sounds are produced due to the closure of heart valves. A stethoscope is used to hear heart sounds The first heart sound makes a ‘lubb’ sound. The second heart sound makes a ‘dupp’ sound. The first heart sound is due to the closure of the atrioventricular valves. The second heart sound is due to the closure of the semilunar valves. © 2019 McGraw-Hill Education  51 Heart Valve Locations Figure 12.19 © 2019 McGraw-Hill Education ©Juice Images/Alamy RF  52 Regulation of Heart Function 1 Stroke Volume: volume of blood pumped per ventricle per contraction 70 milliliters/beat Heart Rate: number of heart beats in 1 min. 72 beats/min. © 2019 McGraw-Hill Education  53 Regulation of Heart Function 2 Cardiac Output: volume of blood pumped by a ventricle in 1 min. 5 Liters/min. Cardiac output equals stroke volume multiplied times heart rate CO = SV x HR © 2019 McGraw-Hill Education  54 Intrinsic Regulation of the Heart 1 Intrinsic regulation refers to the mechanisms contained within the heart itself that control cardiac output. Venous return: the amount of blood that returns to heart Preload: the degree ventricular walls are stretched at end of diastole Venous return, preload, and stroke volume are related to each other © 2019 McGraw-Hill Education  55 Intrinsic Regulation of the Heart 2 Starlings Law of the Heart: relationship between preload and stroke volume influences cardiac output Example - exercise increases venous return, preload, stroke volume, and cardiac output After load: pressure against which ventricles must pump blood © 2019 McGraw-Hill Education  56 Extrinsic Regulation of Heart Extrinsic regulation refers to mechanisms external to the heart, such as either nervous or chemical regulation. Nervous system control of the heart occurs through the sympathetic and parasympathetic divisions of the autonomic nervous system. influences of heart activity are carried through the autonomic nervous system. Both sympathetic and parasympathetic nerve fibers innervate the SA node. © 2019 McGraw-Hill Education  57 Baroreceptor Reflex 1 The baroreceptor reflex is a mechanism of the nervous system that plays an important role in regulating heart function. Baroreceptors: monitor blood pressure in the aorta and carotid arteries changes in blood pressure cause changes in frequency of action potentials involves the medulla oblongata © 2019 McGraw-Hill Education  58 Baroreceptor Reflex 2 Figure 12.20 © 2019 McGraw-Hill Education  59 Chemoreceptor Reflex 1 The chemoreceptor reflex involves chemical regulation of the heart. Chemicals can affect heart rate and stroke volume. © 2019 McGraw-Hill Education  60 Chemoreceptor Reflex 2 Chemical actions: epinephrine and norepinephrine from the adrenal medulla can increase heart rate and stroke volume excitement, anxiety, and anger can increase cardiac output depression can decrease cardiac output medulla oblongata has chemoreceptors for changes in pH and CO2 K+, Ca2+, and Na+ affect cardiac function © 2019 McGraw-Hill Education  61 Chemoreceptor Reflex—pH Figure 12.21 © 2019 McGraw-Hill Education  62 Summary of Extrinsic Regulation Figure 12.22 © 2019 McGraw-Hill Education  63 Heart Disease Coronary Artery Disease due to decrease blood supply to the heart coronary arteries are narrowed for some reason Myocardial Infarction (heart attack) due to closure of one or more coronary arteries area(s) of cardiac muscle lacking adequate blood supply die, and scars (infarct) © 2019 McGraw-Hill Education  64 Heart Procedures Angioplasty: procedure opens blocked blood vessels Stent: structures inserted to keep vessels open Bypass: procedure reroutes blood away from blocked arteries © 2019 McGraw-Hill Education