UNC-Chapel Hill EXSS 276 - EXAM 5 Study Guide (15 pages)

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EXAM 5 Study Guide



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EXAM 5 Study Guide

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Pages:
15
School:
University of North Carolina at Chapel Hill
Course:
Exss 276 - Human Physiology
Human Physiology Documents
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Chapter 20 The Heart Anatomy of the Heart o Size of fist o Location Sits on mediastinum an atomical region that extends from the sternum to the vertebral column About 2 3 lies to the left of the body s midline o Apex of heart bottom of heart Formed by the tip of left ventricle and rests on the diaphragm o Heart Layers 3 layers Pericardium membrane outer layer Membrane that surrounds and protects the heart 2 main parts fibrous pericardium serous pericardium has freedom to contract pericarditis inflammation of the pericardium o leads to a build up of pericardial fluid that compresses the heart and makes it hard to fill up pericardial fluid helps reduce friction between layers 1 Epicardium contains coronary vasculature Has adipose tissue that houses the major coronary and cardiac vessels of heart 2 Myocardium Responsible for the pumping action of the heart Composed of cardiac muscle tissue o have striated involuntary fibers 3 Endocardium smooth and helps minimize friction Innermost layer o Heart Structures 4 chambers 2 superior receiving chambers atria o right and left atrium 2 inferior pumping chambers ventricles o right and left ventricles Arteries carry blood away from heart Coronary artery main supply of blood Aorta splits off and goes to various systemic arteries that supply body Veins carry blood to heart Superior vena cava inferior vena cava both dump into right atrium Coronary sinus dumps into right atrium o From blood actually supplying heart o The Heart Highway Right atrium goes thru tricuspid valve to right ventricle thru pulmonary valve to pulmonary trunk arteries go to lung then pulmonary veins goes to left atrium thru bicuspid valve to left ventricle thru aorta valve to aorta goes to aorta arteries capillaries veins vena cava o Myocardial Wall Thickness pressure and work done by chamber High blood pressure is bad bc the heart has to pump harder Ventricle walls are thicker than atria Left ventricle is much thicker because the blood is going to the whole body Circulation o Principal types Pulmonary right Receives dark red deoxygenated blood from systemic circulation o From body to lung R ventricle pulmonary valve pulmonary trunk arteries lungs pulmonary veins left atrium Systemic left Receives red oxygenated blood from the lungs o Pumps blood at higher pressure Blood enters systemic arteries that carry it to all organs throughout the body o Except for the air sacs alveoli Give rise to smaller diameter arterioles lead into extensive beds of systemic capillaries Left ventricle aortic valve aorta capillaries vena cava coronary artery right atrium o The output of one becomes the input of the other o YOU TRI BEFORE YOU BI o Right to left Atrioventricular Valves o Also known as tricuspid and bicuspid valve Because located between atrium and ventricle o Blood flow is unidirectional o When open relaxed because chordae tendineae are slack blood moves from a higher pressure in the atria to a lower pressure in the ventricles o When closed papillary muscle contracts tighten up to prevent the blood from flowing back into the atria Semilunar Valves o Also known as the aortic and pulmonary valves o When ventricles are relaxed closed blood flows back toward the heart blood backflow caught by cusp o When the ventricles contract the open because the pressure builds up within the chamber that exceeds the pressure in the arteries aorta Coronary Blood Flow 3rd circulation o Cardiac fibers do not fatigue because they have a well established network of blood vessels that supply oxygen and nutrients to it the majority of heart stays in a relaxed state o prevent substrate depletion metabolite accumulation due to large vessels that are supplying the heart Coronary arteries Left and right coronary arteries supply the oxygenated blood to the myocardium o Heart looks after itself soon as blood leaves ventricle it goes back to the heart Circumflex branch lies in the coronary sulcus and distributes oxygenated blood to the walls of the left ventricle and left atrium o Wraps around to get back side of heart Coronary Veins Veins pick up and drain coronary arteries Collect deoxygenated blood All veins drain back into vena cava o Vena cava goes to rt atria back into pulmonary circulation Heart attack MI o A disruption of coronary artery blood flow Not receiving the nutrients or oxygen it needs Becoming ischemic o Inhibit the amount of blood flow going into tissue that puts stress strain on cardiac fibers o Energy substrates for heart Fats burn thru aerobic glycolysis Lactate acid Waste product from skeletal muscle o Risk factors Atherosclerosis hardening of the blood vessels Obesity Having a Y chromosome males Affect older people Physical inactivity Sitting around not moving around o Which coronary artery would be the biggest concern for blockage in artery Left coronary because it provides blood to the left ventricle the walls are thicker in left ventricle and supplies a stronger amount of blood no blood to the left ventricle no blood to the rest of the body brain vital organs muscles etc o if we kill all tissues cardiac output will be diminished more fibers affect more fibers die no contraction Heart Tissue Death Regeneration o Not all heart attacks are fatal o The more tissue affected poor cardiac function output o Muscle is post mitotic no longer able to divide Once heart is matured no fibers can be replaced o If heart tissue is damaged tissue can be regenerated Transplant cases Study where male receives heart transplant from female donor Organ transplant NMJ o Nervous system and heart communicate thru the ANS o Dual innervation o Adjust rate at nodes SA VA and ventricle o Parasympathetic slows HR down Vagus nerve o Sympathetic increases HR Cardiac nerves Harder contraction moves more blood Autorhythmicity o Cells self excite depolarize spontaneously on their own o Generate action potential o SA AV nodes have pacemaker cells During embryonic development only 1 of the cardiac muscle fibers become autorhythmic fibers o Fibers also form cardiac conduction system heart contraction 5 parts Sinoatrial SA node In right ventricular wall top of atria They repeatedly slowly depolarize to threshold spontaneously pacemaker potential o Reaches threshold it triggers an action potential o Each action potential propagated thru both atria via gap junctions in the intercalated discs of atrial muscle fibers 2 atria contract at same time Natural rate 100 time per minute o No nervous system input No SA node cardiac


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