BSC 216- Week 2 Notes
BSC 216- Week 2 Notes BSC 216
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This 4 page Class Notes was uploaded by Alexia Acebo on Monday September 5, 2016. The Class Notes belongs to BSC 216 at University of Alabama - Tuscaloosa taught by Austin Hicks in Fall 2016. Since its upload, it has received 27 views. For similar materials see Human Physiology & Anatomy II in Biology, Arts and Sciences at University of Alabama - Tuscaloosa.
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Date Created: 09/05/16
Lecture 3 Chapter 17: THE HEART Location- mediastinum Functions 1. Pump blood through pulmonary/ systematic circuits 2. Endocrine organ▯ maintain bp Pericardium: membranous structure that surrounds (2x walled)- outer=parietal, inner=visceral Serosa=serous membrane 3 LAYERS 1. Epicardium (visceral pericardium) 2. Endocardium 3. Myocardium Coronary Circulation ▯5% of blood is pumped back to heart to support strenuous workload Angina Pectoris: chest pain from partial obstruction of coronary blood flow Myocardial Infaction: heart attack THE GREAT VESSELS • Superior/Inferior Vena Cava • Pulmonary Trunk (considered artery) • Pulmonary Veins (considered vein) • Aorta THE CHAMBERS 4 • R & L atria o 2 superior chambers o Receive blood returning to heart • Interatrial Septum o Wall to separate atria • R & L ventricles o 2 inf. Chambers o pump blood into arteries • Interventricular Septum o Wall that separates Pulmonary Circuit- short, low p (fed by R ventricle Systematic circuit- long, lots of resistance to flow (L ventricle) THE VALVES Ensure one-way blood flow 1. Atrioventricular valves- control flow between atria & ventricles a. R AV valve: 3 cusps (tricuspid) b. L AV valve: 2 cusps ( bicuspid) c. Chordae tendineae: chords connect valves to papillary muscles 2. Semilunar Valves- control flow into great arteries a. Pulmonary: R ventricle and trunk b. Aortic: L ventricle and aorta 2 MAIN types of Cardiac cells: • (~1%) pacemaker cells • (~99%) contractile cells o Autorhythmicity= ability to set own rhythm w/o nervous system Structure of Cardiac Muscle • Cardiocytes • Intercalated disks 1. Interdigitating folds 2. Mechanical junctions 3. Electrical Junctions Lecture 4 Pacemaker Physiology • SA node does not have stable RMP o Starts @ -60mV & increase from slow Na influx o Gradual depolarization= pacemaker potential Each depolarization of SA node sets off 1 heartbeat Impulse▯ myocardium -SA node stimulates both atria -signal slows through AV node -signal travels quickly through AV bundle and purkinje fibers -ventricular systole progresses up from heart apex Cardiac Conjuction System • Coordinates heartbeat • No outside nervous stimuli necessary • Intercalated discs are key for coordinated contraction order of generation 1. SA node 2. Signals through atria 3. AV node 4. AV bundle 5. Purkinje fibers Nerve Supply to Heart • Sympathetic▯ raise HR • Parasympathetic▯ slow HR Electrocardiogram (ECG/EKG) -composite of all AP’s of nodal and myocardial cells Cardiac Rhythm • Sinus- normal HR triggered by SA node o 60-100 • Ectopic- another part of hreart fires before SA node Arrhythmia- any abnormal cardiac rhythm ▯ heart block- some signals not trans. Through AV node • Premature ventricular contractions: spontaneous firing of ectopic foci before SA node • Ventricular Fibrilation: no coordination (quivering) Contractile Activity of Heart • Systole: atrial or ventricular contraction • Diastole: relaxation • Pressure gradient Lub (s1)- closing of cuspid valves Dub (s2) closing of semilunar valves Events of Cardiac Cycle 1. Ventrical filling phase 2. Isovolumetric contraction phase 3. Ventricular ejection phase 4. Isovolumetric relaxation phase
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