PHYSIOL 335 Chapter Notes - Chapter 12: Pericardium, Endocardium, Purkinje Fibers
31 Oct 2016
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Physiology 335 pre-lab recording notes (lab 5: ecg) Cardiac cells excitable cell (can fire ap to create tension) Ecg measures the electricity moving through the cardiac cells. Not much of a latent period tension develops soon. Conduction pathway of the heart: pacemaker cells, conducting cells, contractile cells, begins at the sa node, cell acts as one big cell electrical syncytium, one pqrst = one heartbeat. How ecg works: similar to emg. Measuring electrical activity: different from emg. Need 3 leads because heart is 3d. Leads calculate the net directionality and amplitude of the ap (vector) 12 limb lead is used clinically: in order for the lead to detect the maximal possible amplitude in the deflection of the wave, the net vector has to travel parallel to that lead. Lead 1 has the greatest amplitude (net vector is running pretty parallel to lead 1. If you see a positive deflection it means the net vector is moving towards the recording electrode.
