BUSINESS Articles? Grades Midterm Review session
REVIEW Cardiac cells Myogenic cells Properties of contractile cells
CONDUCTION SYSTEM OF THE HEART Conduction pathway SA node (pacemaker) atrial depolarization and contraction AV node bundle of His right and left bundle branches purkinje fibers myocardium contraction of ventricles
Sinoatrial node QRS complex Atrial depolarization Ventricular depolarization Ventricular repolarization Atrioventricular node P-Q Interval S-T Segment Q-T Interval Figure 18.16
THE CARDIAC CYCLE Systole versus diastole Three events 1) Recordable bioelectrical disturbances (EKG) 2) Contraction of cardiac muscle 3) Generation of pressure and volume changes
Ventricular volume (ml) Pressure (mm Hg) EKG Electrocardiogram Heart sounds P QRS 1st Left heart T 2nd P Dicrotic notch Pressure changes Atrial systole Left atrium Left ventricle Aorta Changes in volume EDV SV ESV Atrioventricular valves Aortic and pulmonary valves Phase Open Closed Closed Open 1 2a 2b 3 Open Closed 1 Contraction Left atrium Right atrium Left ventricle Right ventricle Ventricular filling Atrial Isovolumetric Ventricular Isovolumetric contraction contraction phase ejection phase relaxation 1 2a 2b 3 Ventricular filling Ventricular filling (mid-to-late diastole) Ventricular systole (atria in diastole) Early diastole Figure 18.20
CARDIAC OUTPUT CO (ml/min) = heart rate (HR) x stroke volume (SV) Factors affecting SV Preload Contractility Afterload
CARDIOVASCULAR SYSTEM Heart Disease
HEART DISEASE Coronary artery disease (CAD) Atherosclerosis Occlusion myocardial ischemia angina pectoris Myocardial infarction
HEART DISEASE Angina pectoris Causes Atherosclerosis Stress induced spasm of coronary arteries Increased physical activity
Referred Pain Gallbladder Appendix Heart Lungs and diaphragm Liver Heart Liver Stomach Pancreas Small intestine Ovaries Colon Kidneys Urinary bladder Ureters Copyright 2010 Pearson Education, Inc. Figure 14.8
HEART DISEASE Myocardial infarction Heart attack Causes Prolonged blockage of coronary arteries Thrombosis Embolism Atherosclerosis
Collateral circulation may prevent infarction
ARRHYTHMIAS Damaged conduction system Classification Rate Atrial flutter Mechanism Fibrillation AV node block Consequences
Sinoatrial node QRS complex Atrial depolarization Ventricular depolarization Ventricular repolarization Atrioventricular node P-Q Interval S-T Segment Q-T Interval Figure 18.16
ARRHYTHMIAS Atrial flutter: prevents normal filling of ventricles regular Sawtooth Pattern Fibrillation: Most common chronic arrhythmia 25-30% loss of efficiency of pumping
ARRHYTHMIAS Ventricular Fibrillation Completely uncoordinated contraction pattern Fatal if not immediately rectified
ABNORMAL EKG S Enlarged P wave Enlarged atrium
ABNORMAL EKG S 1st degree Transmission from SA to AV node delayed 2nd degree Not all SA impulses reach ventricles 3rd degree Complete block = ventricular contraction uncoordinated Infarction, excess vagal tone, drugs
1 st degree ABNORMAL EKG S
2 nd degree ABNORMAL EKG S
3 rd degree ABNORMAL EKG S
ABNORMAL EKG S Bundle Branch Block
ABNORMAL EKG S Enlarged R Q and ST deviations
ABNORMAL EKG S T waves High Low
RISK FACTORS FOR HEART DISEASE High cholesterol High blood pressure Smoking Obesity Inactivity Diabetes mellitus Personalities Family history
CIRCULATORY SHOCK Decreased perfusion to body tissues Mechanisms Cardiogenic shock Hypovolemic shock Vasodilatory shock
CIRCULATORY SHOCK Decline in tissue perfusion tissue hypoxia cells release circulatory mediators compensation Early compensatory mechanisms Vasoconstriction in periphery Vasodilation in coronary and pulmonary circuits Epinephrine Water retention Increased aldosterone ADH
CIRCULATORY SHOCK Vasodilatory and cardiogenic shock High mortality rates
QUESTIONS?