KIN 292 1st Edition Lecture 21 These are the notes from Professor Starnes lecture of Clinical Human Physiology These come from the slideshows provided by the professor and include extra notes and explanations Highlighted or bolded information are things that I believe to be information that is important to look over multiple times The notes in red are my personal additions and quotes of Professor Starnes from the class lecture Outline of Last Lecture I 12 4 Skeletal Muscle Metabolism continued II 12 5 Control of Skeletal Muscle Activity III 12 6 Smooth and Cardiac Muscle preview Outline of Current Lecture I 13 1 Overview of the Cardiovascular System II 13 2 The Path of Blood Flow Through the Heart and Vasculature III 13 3 Anatomy of the Heart IV 13 4 Electrical Activity of the Heart Current Lecture he spent the first half of the lecture finishing up the information from chapter 12 We only got through the first slides of chapter 13 We will finish the chapter 13 slideshow on Wednesday Cardiac Muscle Like skeletal muscle in many ways striated with same sarcomere structure for force development Troponin tropomyosin regulation by Ca2 Different in many ways too Fibers are short connected to others and communicate directly via Gap junctions within intercalated disks All muscles fibers contract each beat regardless of intensity force Does not use summation 1 action potential AP per beat Can generate AP to initiate contraction without nerve stimulus Pacemaker cells spontaneously generate APs 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 Innervated by autonomic nervous system Ca2 comes from extracellular fluid and sarcoplasmic reticulum 100 oxidative energy metabolism all the time Heart one beat one relaxation and one contraction and one action potential Skeletal muscle is different because there are summations in them which means you can have different innervations It won t always be one contraction and one relaxation like cardiac muscle All cardiac muscle fibers contract during a beat Figure 13 2 The path of blood flow through the cardiovascular system CV System components o The heart chapter 13 Blood vessels chapter 14 Blood chapter 15 Functions o Transport of substances Help regulate body temp Cardiovascular system closed system Flow through systemic and pulmonary circuits is in series Left ventricle aorta systemic circuit vena cavae right atrium right ventricle pulmonary artery pulmonary circuit pulmonary veins left atrium left ventricle Repeat at least 1 440 times day 4 champers and 2 atrium Right side receives blood from every place in the body low in o2 Takes blood and pumps to lungs It gets oxygen and dumps out co2 Goes to the left side which pumps fresh blood to all places in body Figure 13 3 Blood Flow patterns in the cardiovascular system Aorta arteries arterioles capillaries Oxygenated blood enters each capillary bed Parallel flow allows independent regulation of blood flow to organs Ex Decrease to GI tract without affecting others Capillaries venules veins Flow to heart in this figure is for flow to coronary arteries in the heart muscle to give it oxygen needed to synthesize ATP needed to pump Pg 363 Figure 13 1 A cutaway view of the heart showing the atria ventricles atrioventricular valves and connections to major blood vessels Size of a fist Weighs 250 350 grams Three layers of the heart wall o Epicardium outer External membrane Myocardium middle Cardiac muscle Endothelium inner Layer of endothelial cells Figure 13 4 Coronary arteries Coronary circulation Heart capillaries are supplied by coronary arteries left and right that arise from the aorta Openings to coronary arteries are immediately above aortic valve heart gets first dibs on oxygenated blood pumped from its left ventricle chamber most aerobic organ in the body There are more veins for heart per muscle Clinical Connections 13 1 Angiogram of a heart showing blockage of the coronary artery Decrease in oxygen delivery greatly decreases ability of the heart to pump because it can only use oxidative energy metabolism even at very high work loads Anaerobic metabolism heart attack 13 4 Electrical Activity of the Heart The conduction system of the heart Spread of excitation through the heart muscle Ionic basis of electrical activity in pacemaker cells Ionic basis of electrical activity in contractile cells Excitation Contraction coupling in contractile cells Electrocardiogram records the electrical activity of the heart ECG done in lab The conduction system of the heart Autorhythmicity the ability to generate own rhythm Heart does this using cells that spontaneously depolarize Mechanism later today The pathway begins in an area in the right atrium known as the sinoatrial node that has the cells that spontaneously depolarize fastest pacemaker cells These then stimulate slower depolarizing dells to beat at pacemaker rate Autorhythmic cells form a pathway shown in yellow for spreading excitation through the heart at rate determined by the pacemaker Interatrial pathway o SA node right atrium left atrium o Rapid o Simultaneous contraction of right and left atria Figure 13 9 Electrical connections between cardiac muscle cells Action potential generated at SA node travels through gap junctions in intercalated disk to spread electrical current from muscle cell to muscle cell Many desmosomes at intercalated disk to hold cells tightly together during the significant mechanical stress that occurs during every heart beat