Oxidative Metabolism O2 taken from blood content O2 in arteries minus content of O2 in veins Lecture 1 Overall design of the circulation Blood Blood Flow Overall design of the circulation Transportation is circulations main job mainly oxygen O2 food Energy CO2 H2O Cardiac Output CO blood flow from heart tissues oxygen delivered to tissues Central circulation VO2 CO CaO2 CvO2 to a tissue VO2t BFt CaO2 CvO2 Right side pulmonary lungs Left side Systemic body System operates by pressure differences p less pressure in pulmonary more pressure in systemic resistance in pulmonary is lower than resistance in systemic Valves only determine the direction of flow Arterial system away from heart Venous system return to heart Pulmonary and systemic blood flow must be equal Blood returning to the heart sets the end diastolic volume EDV Cardiac Output CO is equal to venous return Systemic circulation carries O2 to tissue Left side of heart CO aorta arteries arterioles capillaries High resistance thus high pressure Pulmonary circulation oxygenates blood right side of the heart CO pulmonary artery etc low resistance thus low pressure Venous return high compliance capacity blood resivour high volume low P VR CO VR from systemic to right heart VR from pulmonary to left heart Blood composed of Plasma which includes water ions organic molecules trace elements and vitamins and gases Cellular elements Red blood cells White blood cells and platelets Red blood cells contain Hemoglobin which binds to oxygen and then carries it Red blood cells have a low life expanse so we remake them Oxygen is released from RBC by pressure and squeezing RBC can carry up to 4 molecules of oxygen Platelets are the clotting factor of blood 58 plasma 42 red blood cells 1 white blood cells Average blood volume is between 5 and 6 liters Plasma volume is what creates hydrostatic blood pressure Hematocrit Males 40 54 Females 37 47 Hemoglobin Males 14 17 Females 12 16 This is because males have more mass and oxygen consumption is based on mass also females have menstrual cycles Blood Flow Determinants Pressure difference between two points in the circulation P P1 P2 Resistance to flow Radius 1 r4 length BR 1 L blood viscosity BF 1 v R 1 r4 BF P R BF is proportional to P increase P increase BF Decrease P decrease BF BF is inversely proportional to F increase R Decrease BF decrease R Increase BF A small change in radius is a big change in resistance P causes blood flow which is not proportional to absolute flow No change in P no flow P is the same for both pulmonary and systemic Lecture 2 Anatomy of the heart Blood flow through the heart Autonomic regulation of the heart Anatomy of the heart The heart is behind the chest wall sternum ribs for protection Heart is about the size of your fist Hangs in oblique way 4 valves in specific locations Right AV tricuspid Left AV bicuspid Pulmonary semilunar valve Aortic valve 4 coronary arteries 2 front 2 back that feed the myocardium 3 layers of the heart Pericardium sac around the heart for protection Myocardium muscle that makes up the heart Endocardium endothelium regulation Pericarditis infection of pericardium but it keeps infection away from heart Circulation starts in atrium blood coming back determines cardiac output SA node initiates contraction Myocardium is thicker on the left side of the heart because it needs more pressure to pump blood throughout entire body Pressure is created by muscle contractions think of squeezing a water balloon Need pressure in heart to open valves Myocardial muscle cells are branched and have a single nucleus and area attached to each other by specialized junctions known as intercalated disks which keep the movement of an impulse going in one direction Blood flow through the heart Heart has two phases Diastole relaxation and systole contraction druing ventricular contraction the av valves remain closed to prevent blood flow backward into the atria from flowing back into the ventricles during ventricular relaxation the semilunar valves prevent blood that has endered the arteries Venous flow goes into rt atrium which is the start point of circulation then to the right ventricle then out to the lungs through the pulmonary artery then back to the left atria then left ventricle and then out to the entire body through the aorta A one way flow through the heart is ensured by the two sets of valves Autonomic control of cardiac function Autonomic cardiovascular control center Sympathetic nerve activity SNA Excitatory increased HR contraction Norepinephrine binding to Beta 1 receptors on the SA node Parasympathetic nerve activity PNA Depressant decrease HR Acetocoline binding to muscolynic receptors on the SA node HR is controlled by the autonomic balance of SNA and PNA which is controlled by the cardiovascular control center Low heart rate high PNA Sedentarty resting 60 80 beats per min 70 average max 220 Age effects heart rate athletes have low resting heart rate and very high parasympathetic activity Lecture 3 Specialized conduction system in the heart Electrical activity of the heart specialized conduction system Electrical activity of the heart cardiac muscle Electrocardiogram Specialized conduction system in the heart SA node is the pace maker of the heart SA node intermodal pathways AV node AV bundle bundle branches purkinje fibers AV node imposes delay while atrium contracts Atria contracts before ventricle All specialized cells have pacemaker potential or auto rhythmicity Specialized cells only make up 1 of the heart Electrical activity of the heart specialized conduction system The membrane is polarized normally Funny channels automatically open at 60 and allow a slow influx of sodium in to depolarize Once the membrane is depolarized to 40 then reaches thresh hold so calcium channels open waide to cause a complete depolarization of the membrane At the top of the peek calcium channels close and potassium channels open to start repolarization then once it goes down to 60 the process starts again SNA opens funny channel wider so rate of sodium intake is faster this speeds up the time it takes to reach the threshold which means faster HR PNA first hyperpolarize the membrane down past 60 funny channels open less widely so it takes longer for sodium to come in and reach thresh hold this makes HR slow down Electrical activity of the heart cardiac muscle Electrical conduction in myocardial cells depends on gap junctions Direction is set by the disks gap
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