Cardiac Action Potential and Excitation-Contraction Coupling | Introduction

Описание: We are back with another amazing and full-of-knowledge physiology video. Here you will get in-depth knowledge about the action potential generated in Cardiac myocytes, and how it excites the cardiac muscle cells, and then lastly, we will link this excitation with the contraction of the heart chambers.

So, if you always wondered, how the heart undergoes contraction and relaxation in such a rhythmical manner, this video is for you.

▬ 📃 Cardiac Action Potential and Excitation Contraction Coupling
The heart is the most hard-working organ of our body, and we know very well, that its main function is the blood transmission throughout the body by its pumping action. And this pumping action, which we call a heartbeat, is not a random process but is well-regulated, by hearts own machinery.

To fulfill the demands of the body, the heart needs to work efficiently and in a rhythmical manner, the phenomenon that plays a role here is the generation of the Action potential. Because only after that, the heart is able to contract.

So in this video, we will learn what the structures involved in a regulated rhythmical heartbeat are, How action potential is generated and its different stages, and lastly, we will link that with the contraction of the heart chambers.

This video will cover the following topics:
🟠 Excitatory and Conductive system of the heart
🟠 Cardiac action potential
🟠 Excitation-Contraction coupling

▬ 📜 Excitatory and Conductive System of the Heart
Network or nodes and conducting cells, which are the pacemaker cells of the heart, together make the conduction or nodal system of the heart. Cells involved in this system can generate action potential and maintain the rhythmic contraction and relaxation of the heart.

This system is also known as the nodal system.

It is mainly composed of:
🔵 Sinoatrial Node or S-A Node
🔵 Atrioventricular or A-V Node
🔵 Bundle of His
🔵 Bundle Branches
🔵 Purkinje fibers

▬ 📃 Cardiac Action Potential
A mechanism by which excitable cells (e.g., Neurons, myocytes) can rapidly transmit electrical signals along their cell membranes and to the adjacent cells, is called Action potential. When this unstable electrical potential is generated within cardiac muscle cells, it is termed Cardiac action potential.

Cardiac action potential undergoes graphical variation in different pacemaker cells and non-pacemaker cardiac myocytes as well. It mainly has 5 stages:
🟠 Stage 4
🟠 Stage 0
🟠 Stage 1
🟠 Stage 2
🟠 Stage 3

▬ 📜 Excitation-Contraction Coupling
As a result of an action potential, during stage 2, Calcium influx inside the cell increases. This influx ultimately causes the release of more calcium inside the cell and affects the cross-bridging between Actin and myosin filaments of the cardiac muscle cell, thus ultimately causing the contraction of cardiomyocytes.

So, the excitation-contraction coupling is actually a process that relates the electrical excitation of the cardiac muscles to the Contraction of the heart. A central process that links electrical excitation to contraction; is calcium mobilization.

We have discussed in detail about this interesting process in this video. So, if you want to learn, watch the complete video!

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