BIO210Y5 Lecture Notes - Lecture 22: Mean Arterial Pressure, Interventricular Septum, Qrs Complex
Document Summary
Ecg (electrocardiogram) represents an electrical current through the heart - not a contraction or sound. Sa node is the first pacemaker node which allows heart to beat alone without being in the body for seconds - because of the action potential. Atria contract when depolarization occurs - atria repolarizes and returns to normal. Depolarizing signal travels down interventricular septum - goes through bundled branches. Qrs complex - ventricles bigger than atria so atria are repolarizing and only qrs signal is seen in the ventricles. Ventricles start to repolarize and go back to resting membrane potential as well. Electrodes (b1, b2, b3) - placed around heart during ecg testing. Moment in time when vessels depolarize, they are refracted and repolarization is refraction which causes the up and down lines on the ecg. Mean arterial pressure (map) = diastolic blood pressure + [(systolic - diastolic)/3]
