NUR 1021C Chapter Notes - Chapter Lab Test 2: Superior Vena Cava, Purkinje Fibers, Atrioventricular Node
10 Feb 2020
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Physiology of the cardiovascular system: the heart. S1-first sound: beginning of ventricular systole, the sounds is cause by closure of the av valves-tricuspid and mitral. S2-second sound: beginning of ventricular diastole; the sound is caused by closure of the semilunar valves-aortic and pulmonic: cardiac conduction system. Automaticity: electrical impulse and contraction independent of the nervous system and generated by the cardiac muscle. Sinoatrial (sa) node: located where the superior vena cava enters the right atrium. The repeated contraction and relaxation of the heart is known as the cardiac cycle. The average stroke volume is about 70 ml per beat. Normal cardiac output is 4 to 8 l/min. Heart rate: heart rate is influenced by many factors including the autonomic nervous system, Contractility: contractility is affected by the autonomic nervous system and certain drugs, drugs that affect contractility are called inotropic drugs, positive inotropic drugs: increase contractility, negative inotropic drugs: decrease contractility.
