Question

11. Describe the generation of pacemaker action potentials and then track the resulting impulse through the cardiac conduction system. Include the names of specific types of channels in the first part of your answer.

Answer 1

In heart electrical impulse are generated by specialised pacemaker cells and spread across the myocardium in order to produce a coordinated contraction in systole. Action potential is generated , characteristic disturbance of potential difference between inside and outside of the cell.

Threshold potential is the potential excitable cell membrane such as myocyte, must reach in order to induce an action potential. This depolarization is caused by very small inward movement of calcium ions across the cell membrane which give rise to action potential.

Action potential has several stages --   Depolarization, repolarization, refractory phase.

Stages -- resting potential, threshold, rising , falling and recovery phase.

Tracking of resulting impulse

Resulting impulse travels or starts from SA node to AV node ( atrioventricular) , there after impulse slows down for short period then goes to Bundle of His then branches of bundle and then through purkinje fibres spread to whole ventricular area