Read the Heart’s Electrical Conduction Path
Pacemaker cells initiate impulses; conduction delays and insulation coordinate atrial and ventricular contraction.
Cardiac Conduction is the central idea in this question pattern. Identify the condition in the stem before applying the method below.
Follow impulse timing
The SAN normally sets heart rhythm. AV nodal tissue delays the impulse briefly before it enters the ventricular conduction system; Purkinje fibres rapidly distribute it through ventricular myocardium. Several cardiac tissues can show spontaneous activity, but the SAN normally dominates.
Separate atria and ventricles electrically
The fibrous skeleton insulates atrial from ventricular muscle except through the AV conduction pathway. This permits atria to contract before ventricles.
Match ventricular ion currents to the action potential
Fast Na⁺ entry produces ventricular depolarisation, sustained Ca²⁺ entry supports the plateau, and K⁺ efflux drives repolarisation. On a channel-permeability graph, match the brief early Na⁺ peak, broader Ca²⁺ plateau, and later K⁺ rise to those phases.
OlympIQ exam lens
- ✓SAN is the normal pacemaker.
- ✓AV node delays conduction.
- ✓Purkinje fibres conduct rapidly.
- ✓Fibrous skeleton electrically separates chambers.
The AV delay coordinates contraction; it does not mean the impulse stops permanently at the node.
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