Chapter 11 The Cardiovascular System

Transcription

1 Essentials of Human Anatomy & Physiology Elaine N. Marieb Seventh Edition Chapter 11 The Cardiovascular System INTERESTING FACTS ABOUT THE HEART... Slides Lecture Slides in PowerPoint by Jerry L. Cook The Cardiovascular System The Heart A closed system of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body The function of the cardiovascular system is to deliver oxygen and nutrients and to remove carbon dioxide and other waste products Location Thorax between the lungs Pointed apex directed toward left hip About the size of your fist Slide 11.1 Slide 11.2a The Heart The Heart: Coverings Figure 11.1 Pericardium a double serous membrane Visceral pericardium Next to heart Parietal pericardium Outside layer Serous fluid fills the space between the layers of pericardium Slide 11.2b Slide

2 Heart Covering The Heart: Heart Wall Pericardial physiology Protects and anchors heart Prevents overfilling Figure 19.2 Three layers Epicardium Outside layer This layer is the parietal pericardium Connective tissue layer Myocardium Middle layer Mostly cardiac muscle Endocardium Inner layer Endothelium Slide 11.4 External Heart Anatomy Figure 11.2a Slide 11.5 The Heart: Chambers Right and left side act as separate pumps Four chambers Atria Receiving chambers Right atrium Left atrium Ventricles Discharging chambers Right ventricle Left ventricle Slide 11.6 Atria of the Heart Ventricles of the Heart Atria are the receiving chambers of the heart Each atrium has a protruding auricle Pectinate muscles mark atrial walls Blood enters right atria from superior and inferior venae cavae and coronary sinus Blood enters left atria from pulmonary veins Ventricles are the discharging chambers of the heart Papillary muscles and trabeculae carneae muscles mark ventricular walls Right ventricle pumps blood into the pulmonary trunk Left ventricle pumps blood into the aorta 2

3 Blood Circulation Pathway of Blood through the Heart and Lungs Right atrium tricuspid valve right ventricle Right ventricle pulmonary semilunar valve pulmonary arteries lungs Lungs pulmonary veins left atrium Left atrium bicuspid valve left ventricle Left ventricle aortic semilunar valve aorta Aorta systemic circulation Figure 11.3 Slide 11.7 Gross Anatomy of Heart: Frontal Section Figure 19.4e The Heart: Valves Allow blood to flow in only one direction Four valves Atrioventricular valves between atria and ventricles Bicuspid valve (left) Tricuspid valve (right) Semilunar valves between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve Slide 11.8 Heart Valves The Heart: Valves Valves open as blood is pumped through Held in place by chordae tendineae ( heart strings ) Close to prevent backflow Figure 19.9 Slide

4 Operation of Heart Valves The Heart: Associated Great Vessels Aorta Leaves left ventricle Pulmonary arteries Leave right ventricle Vena cava Enters right atrium Pulmonary veins (four) Figure 11.4 Slide Enter left atrium Slide Coronary Circulation The Heart: Conduction System Blood in the heart chambers does not nourish the myocardium The heart has its own nourishing circulatory system Coronary arteries Cardiac veins Blood empties into the right atrium via the coronary sinus Intrinsic conduction system (nodal system) Heart muscle cells contract, without nerve impulses, in a regular, continuous way Slide Slide 11.13a The Heart: Conduction System Heart Contractions Special tissue sets the pace Sinoatrial node Pacemaker Atrioventricular node Atrioventricular bundle Bundle branches Purkinje fibers Contraction is initiated by the sinoatrial node Sequential stimulation occurs at other autorhythmic cells Slide 11.13b Slide 11.14a 4

5 Heart Physiology: Sequence of Excitation Heart Physiology: Sequence of Excitation Sinoatrial (SA) node generates impulses about 75 times/minute Atrioventricular (AV) node delays the impulse approximately 0.1 second Impulse passes from atria to ventricles via the atrioventricular bundle (bundle of His) AV bundle splits into two pathways in the interventricular septum (bundle branches) Bundle branches carry the impulse toward the apex of the heart Purkinje fibers carry the impulse to the heart apex and ventricular walls Heart Contractions s Figure 11.5 Slide 11.14b Electrocardiography Electrocardiography Electrical activity is recorded by electrocardiogram (ECG) P wave corresponds to depolarization of atria QRS complex corresponds to ventricular depolarization T wave corresponds to ventricular repolarization Atrial repolarization record is masked by the larger QRS complex Figure

6 Filling of Heart Chambers the Cardiac Cycle Y Figure 11.6 Slide The Heart: Cardiac Cycle Atria contract simultaneously Atria relax, then ventricles contract Systole = contraction Diastole = relaxation The Heart: Cardiac Cycle Cardiac cycle events of one complete heart beat Mid-to-late diastole blood flows into ventricles Ventricular systole blood pressure builds before ventricle contracts, pushing out blood Early diastole atria finish re-filling, ventricular pressure is low Slide Slide The Heart: Cardiac Output Cardiac Output Regulation Cardiac output (CO) Amount of blood pumped by each side of the heart in one minute CO = (heart rate [HR]) x (stroke volume [SV]) Stroke volume Volume of blood pumped by each ventricle in one contraction Slide Figure 11.7 Slide