The Electrical System of The Heart
The heart is a muscle that contracts to pump blood to the
body. The heart has two upper chambers – the atria and two lower chambers – the
ventricle.
Atria and Ventricles are separated by heart valves that are
meant to allow blood to only flow forward. The ventricle is the more muscular
part of your heart and responsible for over 80% of the blood flow. The atria
are thinner, but also very important to help with blood flow.
The atria and ventricles contract in an organized sequence
which is very efficient. That sequence is controlled by the electrical system
of the heart: the sinus node, AV node and His-Purkinje system.
 |
| The Normal Rhythm of the Heart |
Sinus Node
Your heart has a specialized electrical system that
essentially tells the muscle when to beat or contract. The electrical impulse
begins in the Sinus node. The Sinus node is located in the right atrium, and is
your own natural pacemaker – telling the heart when it is time to beat. It
controls the rate and increases it as needed – for example during exercise.
When your heart is in normal rhythm, it is called sinus
rhythm because the sinus node is controlling when each heart beat is going to
happen.
After the Sinus node start the contraction in the right
atrium, the electrical activity travels through the right and left atrium
causing that part of the heart to contract, pushing blood forward, into the
right and left ventricles.
The atria is not nearly as important as the ventricle in
terms of heart pumping function. However, it is very important in regulating
the normal heart rhythm (via the sinus node). The atria is also the origin of
many heart rhythm disorders, such as atrial fibrillation or other so called supraventricular
arhythmias.
AV node
After the activity starts in the sinus node it goes into the
AV node. The AV node is best described as a wire that connects the upper and
lower chambers, sending the electrical impulse that started in the sinus node
into the ventricle, telling it to contract.
His-Purkinje System
The impulse then travels from the AV node via specialized
cells that act as wires that will send the signal to contract to the right and
left ventricles.
When the normal sequence is followed
1.
Impulse originates in the sinus node and quickly
spreads into the right and left atria
2.
Atria will contract causing blood to flow into
the ventricles
3.
The electrical impulse will goes through the AV
node, which causes a small delay, allowing the ventricles to fill with more
blood
4.
Electrical impulses are then conducted quickly
via the His-Purkinje system into the entire right and left ventricles
5.
As the electrical impulses reach the heart
muscle, the right and left ventricles will contract
6.
When the ventricles contract the mitral and
tricuspid valves will close causing the blood to be ejected forward, into your
lungs or you body.
No comments:
Post a Comment