BIOL 320 1 st Edition Lecture 8 Outline of Last Lecture I Coronary Circulation Clinical Correlations II Heart Microscopic Anatomy III Heart Physiology Action Potentials of Auto rhythmic Cells IV Conduction System of the Heart V Regulation of Heart Rate VI Electrocardiography Normal and Abnormal ECG Tracings VII Heart Dysfunction Outline of Current Lecture VIII Cardiac Cycle IX Cardiac Output Flow Chart to Increase Cardiac Output X Regulation of Stroke Volume SV Three Factors that Regulate SV XI Effects of Calcium in Cardiac Muscle XII Heart Development XIII Congenital Heart Defects XIV Aging of the Heart I II III Blood Vessels Structure Arteries Capillary Beds sites of gas exchange Thoroughfare channel bypass capillary bed Current Lecture Cardiac Cycle As P wave is occurring electrical stimuli activating the atria the AV nodes open get the blood into the ventricles QRS complex ventricles are contracting so the SL valve is open gets open from the blood pressure pushing up on it forcing it to open AV valve is closed delay due to ECG reading depolarization First sound is AV valve closing T wave ventricular repolarization Second sound SL valve closing End Diastolic Volume full End Systolic Volume empty EDV ESV Stroke Volume Systole contracting Diastole relaxing Cardiac Output Cardiac Output CO volume minute blood pumped by ventricles CO ml min HR beats min x SV ml beat o CO Cardiac Output o HR Heart Rate o SV Stroke Volume SV EDV ESV o SV Stroke Volume o EDV End Diastolic Volume o ESV End Systolic Volume Extra Notes o Average blood volume is being pumped throughout your body every minute o Heart is fullest at diastole o Heart is emptiest at systole Flow Chart to Increase Cardiac Output Regulation of Stroke Volume SV Three Factors that Regulate SV o Preload degree of stretch of cardiac muscles Frank Starling Law of the Heart o Contractility intrinsic ability of tissue to contract ex greater calcium influx greater contractility anything that increases S ANS input glucagon digitalis epinephrine thyroxin o Afterload pressure of aortic blood on SL valve aortic valve weight of blood on cusps hypertensive patient heart will have to work harder because it puts strain on heart not a problem if healthy Blood Loss Rapid Heartbeat when blood volume goes down blood pressure goes down tachycardia will also decrease volume because less time to refill both result in decreased SV Effects of Calcium in Cardiac Muscle Heart Development Foramen ovale bypass pulmonary circuit since gas exchange is occurring by the placenta fossa ovale is the scar of this in the adult heart Congenital Heart Defects Ventricular Septal Defect the superior part of the inter venticular septum fails to form thus blood mixes between the two ventricles More blood is shunted from left to right because the left ventricle is stronger Coarctation of the Aorta a part of the aorta is narrowed increasing the workload of the left ventricle Tetralogy of Fallot multiple defects tetra four o Pulmonary trunk too narrow and pulmonary valve stenosed resulting in o Hypertrophied right ventricle o Ventricular septal defect o Aorta opens from both ventricles Aging of the Heart Sclerosis Thickening of Valve Flaps o Most common site mitral valve o Result heart murmur leaking of blood through valve Cardiac Reserve Decline o Cardiac reserve heart s ability to respond to sudden prolonged cardiac output o Sympathetic control less efficient o Heart rate more variable o Example clich of older man with younger woman asystole no pumping Fibrosis of Cardiac Muscle o Stroke volume decreases o Fibrosis of nodes increased incidence of arrhythmias Atherosclerosis o Contributing factors inactivity smoking high cholesterol diet stress genetics o Consequences hypertension coronary arteries occlude o Risks stroke and heart attack Blood Vessels Structure Tunics o Arteries vs Veins Arteries lumen is smaller thickness is thicker Veins lumen is larger thickness is thinner o Tunica intima innermost layer Endothelium same as what is in heart o Tunica media middle layer Smooth muscle and elastic fibers o Tunica externa outermost layer Collagen fibers Arteries Physical characteristics serve to decrease shock and even out flow Muscular artery supply organs tissue with blood o If faucet wide open pressure flow decreases o Blood is time shared by tissues vasoconstriction vasodilation o Limit flow to inactive areas Arteriole connect arteries to capillaries o Can vasoconstrict to further limit flow to inactive area Capillary Beds sites of gas exchange create a micro circulation Pre capillary sphincters if closed blood doesn t flow through if open it does True capillaries vessels after pre capillary sphincter Thoroughfare channels bypass capillary bed when pre capillary sphincters are closed Pericytes smooth muscle like cells stabilize capillary walls Tissues without tendons and ligaments cartilage and epithelial tissue none at all cornea eyeballs Function exchange of gases nutrients hormones wastes