Thin myocytes with fewer gap junctions b Delays signal 100 msec allows

Thin myocytes with fewer gap junctions b delays

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Thin myocytes with fewer gap junctions b. Delays signal 100 m/sec, allows ventricles to fil III. AV bundle and Purkinje fibers (fast) a. Speeds signal along at 4 m/sec to ventricles IV. Ventricular systole (contraction) begins at apex, progresses up Contraction of Myocardium I. Note: rising phase of AP due to Na + influx, NOT Ca 2+
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A&P Test 2 II. Plateau due to Ca 2+ influx (slow channels) a. Plateaus to make the electrical event last longer Electrocardiogram (ECG) I. Composite of all action potentials of nodal and myocardial cells detected, amplified and recorded by electrodes on arms, leg and chest II. Absence or abnormalities of any component is due to specific problems with the heart I. P wave a. SA node fires, atrial depolarization b. Atrial systole (contraction) II. QRS complex a. Ventricular depolarization b. Atrial repolarization and diastole – signal obscured III. ST segment a. Ventricular systole (contraction) IV. T wave a. Ventricular repolarization V. Quiescent period a. The time between waves (can change) VI. Contraction a. Atrium first ventricle second – helps to fill ventricles will blood ECGs, Normal and Abnormal
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A&P Test 2 A. Sinus rhythm (normal) a. How it should look B. Nodal rhythm – no SA node activity a. SA node isn’t firing b. No P wave C. Heart block a. No QRS complex b. Conduction failure at AV node D. Premature ventricular contraction a. Extra systole b. Note: inverted QRS complex E. Ventricular fibrillation a. Not pumping any blood Heart Sounds I. Auscultation – listening to sounds made by body II. First heart sound (S 1 ), louder and longer “lubb”, occurs with closure of AV valves a. Lubb – dub sound is when the AV valve closes then the semilunar closes III. Second heart sound (S 2 ), softer and sharper “dupp” occurs with closure of semilunar valves IV. S 3 – rarely heard in people > 30 V. The sound is the blood hitting the closed valve Cardiac Cycle I. One complete contraction and relaxation of all 4 chambers of the heart II. Systole – contraction
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A&P Test 2 III. Diastole – relaxation IV. Atrial systole, ventricle diastole V. Atrial diastole, ventricle systole VI. Quiescent period Remember: -Pressure during quiescent period -Aorta – dicrotic notch: a pressure bounce in the aorta - without it the pressure would be lower -both valves are never open -most filling of blood in the ventricle is passive and happens during quiescent period -SV is stroke volume -EDV is end diastolic volume; ESV is end systolic volume
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A&P Test 2 Balanced Ventricular Output Blood Vessels Anatomy of Blood Vessels I. Arteries carry blood away from heart II. Veins carry blood back to heart III. Capillaries connect smallest arteries to veins 3 Layers of Vessel Wall I. Tunica Interna (intima) a. Smooth inner layer that repels blood cells and platelets b. Simple squamous endothelium overlying a basement membrane and layer of fibrous tissue II. Tunica media a. Middle layer b. Usually thickest; smooth muscle, collagen, some elastic c. Smooth muscle for vasomotion III. Tunica Externa (tunica adventitia) a. Outermost layer b. Loose connective tissue with vasa vasorum
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