BIOL 252 1st Edition Lecture 18 Outline of Last Lecture I B cells II Antigen presenting cells III Cellular immunity IV Humoral Immunity V Immunological Memory VI Forms of Immunity VII Heart Physiology VIII Cardiac Rhythm IX Pacemaker cells has unstable RMP X Comparison of Cardiac and Skeletal Muscle APs Outline of Current Lecture I Poll Everywhere II ECG EKG III Principles of Pressure and Flow IV Heart Sounds V Phase of Cardiac Cycle VI How much blood does the heart pump Current Lecture I Poll Everywhere a Verapamil is a calcium channel blocker used to treat hypertension It selectively blocks slow calcium channels How does it lower blood pressure It is a 1 Positive chronotropic agent 2 Negative chronotropic agent 3 Positive inotropic agent 4 Negative inotropic agent negatively affects contraction strength a How does it lower blood pressure b Less calcium less contraction strength ii Pacemaker cells modulate heart rate SA node cells iii Inotropic group of cells affected by contractility cardiomyocytes iv Contractile cells responsible for producing blood pressure v Slow calcium channels cardiomyocytes 1 Gives plateau phase 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 2 3 If blocking slow calcium channel what is the missing step 4 Calcium coming in to cardiac muscle cells part of calcium that triggers contraction a In skeletal muscle comes from sarcomere b In cardiac muscle comes from SR and extracellular fluid vi Refractory period ensures unidirectional AP build in space so heart cannot receive another AP prolongs period of AP II III ECG EKG a Two electrodes plus a third ground b P wave atrial depolarization top to bottom i Goes from one cell to the next via gap junction c QRS complex atrial repolarization and ventricular depolarization bottom to top i Atria stimulation from SA node ii Ventricles stimulated by Purkinje fibers reason direction is bottom to top time delay benefit d T wave ventricular repolarization Principles of Pressure and Flow a Pressure force area i Exerted in all directions omnidirectional ii Hydrostatic pressure fluid pressure b Flow i Proportional to pressure ii Small difference in pressure small movement in fluid c Pattern of blood moving through the heart i Atria low pressure 1 Atria contract systole ii At same time ventricles are relaxed diastole iii Difference in pressure moves blood to ventricles iv Atria relax diastole while ventricles contract systole v Both sides of heart do that same thing vi Blood pushes AV valves closed atrioventricular valves 1 How we pressurize blood vii To move blood out of the heart 1 Ventricles continue contracting systole IV V 2 Semilunar valves pushed open a Aortic and pulmonary trunk 3 Difference in pressure moves blood out of ventricles viii Ventricles relax and atria relax 1 Blood pushes semilunar vales closed 2 Pressure drives blood throughout entire body Heart Sounds a Valves closing makes noise b S1 AV valve closing c S2 semilunar valve closing d Valvular insufficiency i Causes 1 Stenosis narrowed opening surrounded by scar tissue 2 Valvular prolapse sticking out in wrong direction 3 Congenital malformation e Phillip was diagnosed with AV Valvular prolapse Which would you NOT predict i His ventricles would be enlarged ii Atria would be enlarged 1 Atria pumping against greater pressure must work harder iii Heart rate would be greater than normal 1 If not able to pump as much blood as normal person must compensate iv Blood pressure in his aorta would be within a normal range 1 If heart is compensating beating faster to move same amount of blood expect that the blood pressure would come up as normal Phase of Cardiac Cycle a ESV end systolic volume i Volume of blood in ventricle at the end of its contraction ii Not zero 70 mL b Diastole contraction blood volume increasing i Blood coming from atrium ii iii Blood volume increases passively until atria contracts iv EDV end diastolic volume 130 mL v Ventricle contracts and volume goes down 1 Blood goes to aorta for left ventricle VI 2 Stroke volume SV EDV ESV 3 Ejection fraction SV EDV a In this case 50 How much blood does the heart pump a Heart rate x stroke volume cardiac output i Heart rate depends on SA node cells ii Stroke Volume depends on cardiomyocytes b mL per minute c At rest cardiac output 5 L minute d At max cardiac output 25 L minute i Increase during exercise to use oxygen more readily ii If an athlete can increase cardiac reserve e How does heart rate change i Chronotropic agents affects on nodal cells 1 Increase Sympathetic NS NE hormones NE and TH 2 Decrease Parasympathetic NS ACh 3 Tachycardia and bradycardia are abnormal heart rates ii When body becomes active proprioceptors in muscles and joints provide info on movement iii When blood chemistry changes chemoreceptors provide info on pH and CO2 1 High CO2 acidic pH iv When your brain tells it to v When blood pressure changes baroreceptors provide info on blood pressure 1 High BP slow heart down