The Cardiac Action Potential

The Cardiovascular System

In this course, Ms Aarushi Agrawal (King’s College London) talks about the cardiovascular system. We begin by: (i) looking at how the cardiac action potential differs from a general action potential; before (ii) looking at how muscles contract using the sarcomere, the unit of the muscle; and then (iii) discussing the structure and function of the heart and cardiac cycle; preceding (iv) discussing the structure and function of haemoglobin and oxygen dissociation curves; and finally (v) discussing some of the cardiovascular diseases such as atherosclerosis and myocardial infarctions.

The Cardiac Action Potential

In the first mini-lecture, we introduce the cardiac action potential. To do so, we begin by looking at the mechanism of a general action potential involving potassium, sodium, calcium and chloride ions. We look at the individual stages by investigating a graph looking at the voltage across a nervous membrane over time. We talk about the point of stimulus, followed by depolarization and repolarization, the refractory period and the resting state. Doing so helps us compare the general action potential with the cardiac action potential, and the movement of ions throughout the stages of depolarization and rapid repolarization.