Lab Exercise 31 - Conduction System of Heart

Lab Exercise 31 - Conduction System of the Heart
functional syncytium
entire myocardium acts as single unit do to cardiac muscles being connected by gap junctions
intrinsic conduction system/nodal system
consists of specialized non-contractile myocardial tissue, ensures heart contracts (depolarizes) orderly, beats as coordinated unit
Sinoatrial Node (SA Node)
pacemaker of the heart, signals contraction of atria
Atrioventricular Node (AV Node)
signals contraction of ventricles
purkinje fibers (conduction myofibers)
spread signal up into ventricles = contraction
electrocardiogram (ECG)
graphic recording of electrical changes during cardiac cycle; records time & voltage only
p wave
atrial depolarization, 1st small bump on graph
QRS complex
ventricalular depolarization, spiked area on graph (atrial repolarization)
t wave
ventricular repolarization, 2nd slightly bigger bump after the qrs complex
heart rate over 100 bpm
heart rate below 60 bpm, athletes is ok, can train to increase stroke volume w/ lower heart rate
rapid, uncoordinated contractions out of rhythm (prolonged tachycardia can progress to this)