BIOL 2002C 1st Edition Lecture 7 Outline of Last Lecture I Heart Outline of Current Lecture I Continuation of Heart Current Lecture 1 Explain the importance of a long refractory period in cardiac muscle Allows depolarization of entire ventricle so they can contract together stops contraction from happening before one is complete 18 Describe the waves and intervals of an electrocardiogram ECG What does each signify Fig 20 16 P wave atrial depolarization QRS complex ventricular depolarization T wave ventricular repolarization PR interval 0 16 sec atrial systole contraction after the P wave QT interval 0 36 sec ventricular systole beginning of Q wave to end of T right after the QRS complex 20 7 CARDIAC CYCLE 19 Describe the cardiac cycle in terms of atrial and ventricular systole and diastole and approximate length of time of each Fig 20 18 How long does a complete cardiac cycle last How many heart beats per minute will therefore normally occur Atrial systole contraction 0 1sec Ventricular systole contraction with atrial diastole 0 3sec Atrial and ventricular diastole relaxation 0 4sec Each cycle normally takes about 0 8 seconds so there are about 72 75 beats per minute Contraction generates force which moves blood always from area of These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute higher pressure lower pressure Describe isovolumetric contraction and relaxation periods period of ejection etc as shown in Fig 20 18 1 Atrial systole active ventricular fillingoccurs when atria contract and ventricles are in diastole 2 Ventricular systole period of isovolumetric contractionAV valves also closed 3 Ventricular systole period of Ejection force produced by contraction has overcome pressure in aorta of 80mm and in pulmonary arteries of 8mm to open semilunar valves Pressure will increase to 120mm in aorta and 25mm in pulmonary trunk 4 Ventricular diastole period of isovolumetric relaxationBackflow of blood causes semilunar valves to close AV valves also closed 5 Ventricular diastole passive ventricular fillingAbout 70 of blood flows in during diastole before atria contract 20 Describe the cardiac cycle and the relationship among the contraction of each of the chambers the opening and closing of valves the pressure in each of the chambers the phases of the electrocardiogram and the heart sounds Fig 20 19 1 Atrial systole active ventricular filling AV valves open semilunar valves closed pressure in atria and slight pressure in ventricles completion of P wave atrial depolarization and beginning of QRS complex ventricular depolarization 2 Ventricular systole period of isovolumetric contraction AV and semilunar valves closed pressure in ventricles completion of QRS complex first heart sound 3 Ventricular systole period of Ejection AV valves closed and semilunar valves open pressure in ventricles beginning of T wave ventricular repolarization 4 Ventricular diastole period of isovolumetric relaxation AV and semilunar valves closed dicrotic notch due to closure of aortic valve slight increase of pressure pressure in ventricles completion of T wave Second heart sound 5 Ventricular diastole passive ventricular filling AV open and semilunar valves closed pressure in ventricles beginning of P wave Third heart sound 21 Discuss the heart sounds and their significance Lub dupp lub dupp Lub AV valves closing Dupp Semilunar valves closing What are incompetent valves Valves that don t close completely Heart murmurs Occur when blood leaks through the valve Stenosis Narrowing of the valve 20 9 REGULATION OF THE HEART 22 Explain what the equation CO HR X SV means and define what each of the terms mean What are EDV and ESV Know that SV EDV ESV Remind yourself of the meaning of the term ejection fraction Be able to calculate any of these values and be sure you know the correct units for the values Cardiac output CO amount of blood pumped by each ventricle in 1 minute HR beats min X SV ml beat CO ml min Define cardiac reserve maximal CO high activity max is 20 25 Stroke volume SV amount of blood pumped out by a ventricle in 1 beat EDV end diastolic volume amount of blood in a ventricle after diastole ESV end systolic volume amount of blood in a ventricle after contraction Ejection fraction 60 of blood pumped out with ventricles pumping out SV ml beat EDV 125 ml beat ESV 55 ml beat 70 ml beat