Electrocardiography

Electrocardiography - early ventricular diastole o...

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Electrocardiography o Electrocardiograph : measures electrical currents generated during heart contraction with a series of electrodes placed on 12 body regions o Electrocardiogram (ECG or EKG) : recording from electrocardiograph P wave : atrial depolarization QRS complex : ventricular depolarization T wave : ventricular repolarization P-Q interval: beginning of atrial depolarization until beginning of ventricular depolarization Q-T interval: beginning of ventricular depolarization until beginning of ventricular repolarization - Cardiac cycle : all events associated with blood flow through heart o Systole : contraction o Diastole : relaxation (dilation or expansion) o Sequence: ventricular filling (mid to late ventricular diastole)/atrial systole Kevin Kelleher, MTC Biology 211 Study Notes Exam 2 5 ventricular systole/atrial diastole
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Unformatted text preview: early ventricular diastole o quiescent period: period of total heart relaxation (~0.4 sec. of total 0.8 sec. of cycle)- Heart sounds : lub-dup sound o AV valves close o SL valves close o Murmurs : sounds often indicative of valve problems- Cardiac output (CO) : CO = Stroke Volume (SV) x Heart Rate (HR) o normal resting values: SV = 70 ml/beat; HR = 75 beats/min; CO = 5250 ml/min SV = end diastolic volume (EDV) end systolic volume (ESV) Normal resting values: EDV = 120 ml; ESV = 50 ml o cardiac reserve: difference between resting & maximal CO o regulation of stroke volume: preload: degree of stretch of cardiac muscle cells just before contraction contractility: increase in contractile strength afterload: back pressure exerted by arterial blood PAGE4...
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Electrocardiography - early ventricular diastole o...

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