Cardiovascular System Summary

Cardiovascular System Summary - Cardiovascular System...

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1 Cardiovascular System Summary Cardiovascular Basics Primary function of CVS : Transport products to sustain all cells Components : Heart and Blood vessels Heart – "four chambered" – surrounded by epithelium and connective tissue; enclosed in pericardium; right and left side separated by septum Right atrium & ventricle o Pulmonary circuit Left atrium & ventricle o Systemic circuit Blood Vessels – "closed circulation" o Arteries –from heart o Capillaries– cell exchange o Veins – to heart Coronary circulation: The coronary arteries branch off the base of the aorta within the cups formed by the aortic (semilunar) valves. One coronary artery goes to each side of the heart. They run along the surface of the heart in grooves called sulci (singular - sulcus ), branching as they go. The normal heart has little collateral circulation but with coronary heart disease, some collateral circulation may develop. Most of the coronary veins join to form the coronary sinus that opens directly into the right atrium. A few smaller veins open directly into other chambers of the heart. Heart Valves Ensure One-Way Flow in the Heart atrioventricular (AV) valves o chordae tendineae, papillary muscles, tricuspid valve (right), bicuspid valve (left) (mitral valve) semilunar valvesaortic valve, pulmonary valve Myocardial cells Autorhythmic – 1% Myocardial Intercalated discs o Desmosomes o Gap Junctions Fast signals Many mitochondria Large T tubules Sliding filament theory applies Graded Contraction: proportional to crossbridges formed More [Ca ++ ]: crossbridges, more force & speed Stretch-length relationship Strength of contraction proportional to amount of Ca ++ entering Long action potential Long refractory period No summation No tetanus - Cardiac Muscle Cells Contract Without Nervous Stimulation Pacemaker membrane potential I-f channels Na + influx Ca ++ channels – influx, to AP Slow K + open – repolarization
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Cardiovascular System Summary - Cardiovascular System...

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