the heart is an astonishing organs beating approximately 100 000 times per day to pump
blood throughout the body at the core of this remarkable function is the cardiac action
potential which is a series of electrical changes that occur as the heart contracts and relaxes
the action potential is a complex process that involves the depolarization and repolarization
of the heart cells but what is the difference between the two that is exactly what we're
going to discuss in this quick video so if you're ready let's get into it as previously mentioned
the heart is composed of specialized cells that work together to maintain a rhythmic heartbeat the
conduction system of the heart is responsible for generating electrical signals that cause the heart
to contract and relax and the depolarization and repolarization of these cells play a crucial role
in this process depolarization is the process by which the cells of the heart become less negative
and contract when the cells are at rest they are negatively charged and polarized however when an
electrical impulse is generated these cells become depolarized this occurs when the concentration of
ions changes specifically when sodium ions rush into the cells sodium ions move into the cells
through ion channels which are specialized proteins embedded in the cell membrane when
the sodium ions enter the cells they cause the cells to become positively charged which results
in the depolarization of the cells this causes the cells to contract and push blood through
the heart after depolarization and contraction the cells need to relax which is referred to as
repolarization repolarization is the process by which the cells return to their negatively
charged State this occurs when the cell membranes become more permeable to potassium ions which exit
the cell the loss of potassium ions causes the cells to become negatively charged again leading
to relaxation the process of depolarization and repolarization creates the electrical
activity of the heart which is represented as the pqrst waveform on an electrocardiogram or EKG
the sinoatrial node also known as the pacemaker is responsible for setting the heart's rhythm
the wave of depolarization that originates from the SA node is responsible for causing
the Atria to contract this is known as the P wave on an EKG reading the impulse is received by the
AV node which causes a short delay this delay is interpreted as the PR interval on an EKG reading
then the stimulus moves through the bundle of this through the left and right bundle branches and
into the purkinje fibers this produces ventricular depolarization and contraction occurs which can
be seen as the QRS complex on the reading then the heart enters into a short period of repolarization
which is a period where no electrical activity can be detected this is known as the ST segment
on the EKG reading and finally the heart enters a period of recovery where the SA node is recharged
and another cycle can begin so as you can see depolarization and repolarization are important
processes in the electrical conduction system of the heart depolarization leads to the contraction
of the heart while repolarization leads to relaxation these processes are essential for
maintaining a regular heartbeat and ensuring that blood is effectively pumped throughout the body
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Joy just a quick reminder we are not doctors this video is for informational purposes only
thank you so much for watching have a blessed day and as always really easy my friend [Music]