PHYL2001 Lecture Notes - Lecture 5: Purkinje Fibers, Sinoatrial Node, Atrioventricular Node
Document Summary
Nerves and muscle use changes in charge to send electrical signals called action potentials. Cardiac muscle cells uses action potentials to coordinate contraction across the heart and activate contraction. Within the atria and ventricles myocardial cells connected by gap junctions. Gap junctions allow cardiac action potential to propagate from cell to cell through a low resistance pathway. Electrical activity can pass from cell to cell in the atria and ventricles. The atria and the ventricles are electrically isolated by the hearts fibrous skeleton the annulus fibrosus. The heart has specialised electrically active cells in addition to contractile myocardium. These cells for the sinoatrial (sa) node, atrioventricular (av) node, bundle of his and purkinje. Electrical activity normally originates in the sa node. The av node forms the only site of electrical connection between the atrial and ventricles. Action potential (ap) starts at the sa node. The ap is delayed at the av node before entering the bundle of his.
