L21- CARDIOVASCULAR SYSTEM.pdf

L21- CARDIOVASCULAR SYSTEM Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, AUA LEARNING OUTCOMES Describe the Sequence of Excitation of impulses Describe Electrocardiogram (EKG) Describe the cardiac cycle and its various phases Des...

L21- CARDIOVASCULAR SYSTEM Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, AUA LEARNING OUTCOMES Describe the Sequence of Excitation of impulses Describe Electrocardiogram (EKG) Describe the cardiac cycle and its various phases Describe the extrinsic innervation of the heart Describe the Cardiac Output (CO) and its reserve  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) 3  Heart Physiology: Sequence of Excitation 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 4  Heart Physiology: Sequence of Excitation Figure 19.14a 5 6  Electrocardiography Electrical activity is recorded by electrocardiogram (ECG or EKG) P wave corresponds to depolarization of SA node QRS complex corresponds to ventricular depolarization T wave corresponds to ventricular repolarization Atrial repolarization record is masked by the larger QRS complex 7  Electrocardiography Figure 19.16 8 9  Cardiac Cycle Cardiac cycle refers to all events associated with blood flow through the heart Systole – contraction of heart muscle Diastole – relaxation of heart muscle 10  Phases of the Cardiac Cycle Ventricular filling – mid-to-late diastole Heart blood pressure is low as blood enters atria and flows into ventricles AV valves are open then atrial systole occurs 11  Phases of the Cardiac Cycle Ventricular systole Atria relax Rising ventricular pressure results in closing of AV valves Isovolumetric contraction phase Ventricular ejection phase opens semilunar valves 12  Phases of the Cardiac Cycle Isovolumetric relaxation – early diastole Ventricles relax Backflow of blood in aorta and pulmonary trunk closes semilunar valves Dicrotic notch – brief rise in aortic pressure caused by backflow of blood rebounding off semilunar valves 13  Phases of the Cardiac Cycle 14 Figure 19.19a  Phases of the Cardiac Cycle 15 Figure 19.19b 16  Extrinsic Innervation of the Heart Heart is stimulated by the sympathetic cardioacceleratory center Heart is inhibited by the parasympathetic cardioinhibitory center Figure 19.15 17  Heart Sounds Heart sounds (lub- dup) are associated with closing of heart valves Figure 19.20 18 19  Normal Heart Sound Mitral valve prolapse 20 21 22  Cardiac Output (CO) and Reserve CO is the amount of blood pumped by each ventricle in one minute CO is the product of heart rate (HR) and stroke volume (SV) HR is the number of heart beats per minute SV is the amount of blood pumped out by a ventricle with each beat Cardiac reserve is the difference between resting and maximal CO 23  Cardiac Output: Example CO (ml/min) = HR (75 beats/min) x SV (70 ml/beat) CO = 5250 ml/min (5.25 L/min) 24