Cardiac Conduction System: Its Primary Function

The cardiovascular system is such a wondrous system of interconnected networks and functions. All these intricate systems aim to do is keep the heart beating properly and evenly distribute blood in all parts of the body. One of the systems that helps in the overall function of the cardiovascular system is a cardiac conduction system or CCS. It triggers the electrical impulse that is naturally present to the heart.

Person holding a symbolic heart-shaped object to represent the cardiac conduction system

The cardiovascular system is such a wondrous system of interconnected network and function. These intricate systems keep the heart beating properly and evenly distribute the blood in all parts of the body. One of the systems that helps in the overall function of the cardiovascular system is a cardiac conduction system or CCS.

The Cardiac Conduction System

According to MedlinePlus.gov., “The cardiac conduction system is a group of specialized cardiac muscle cells in the walls of the heart that send signals to the heart muscle causing it to contract.”

In other words, the CCS triggers the electrical impulse that is naturally present to the heart. These electrical impulses are responsible for coordinating well the movement of the contraction of each heart chambers. CCS is also patterned to your genetic makeup. Each individual’s CCS is slightly sensitive to how your genetic makeup is structured. To get to know better how CSS works, let us take a look at how the human heart works.

How It All Starts

A human heart functions the first time when a human is still an embryo. Cell division by this time is rigorous as the cardiovascular system is developing further. By this time the essential nutrients needed by the body is circulated.

The first beat of the heart is the first manifestation of CCS. Without this electrical impulse, the heart would not beat at all. These electrical impulses are all performed by CCS. Failure or little aberrations of CCS can lead to arrhythmia. This disorder is typically treated by surgical procedures and therapy. The cardiac conduction cells have the ability to trigger electrical impulses, respond to it, and transmit it from one cell to another.

Sinoatrial Node

The primary pacemaker of the heart is the sinoatrial node or SA node. The SA node is basically the main producers of electrical impulses in a human’s heart. The SA node is a versatile node that rapidly fires impulses depending on the metabolic demands of our body. These impulses are the cause of atrial contractions. The SA node and the myocardial cells in which (electrical impulses go through) determine the heart rate.

The SA node is not the only node responsible for firing electrical impulses there are several nodes in our hearts that can do that. These nodes are reserves if ever the main node has an aberration. The secondary node is called the AV node and the last node is the ventricular node. The electrical impulse traveling across the cell’s membrane is made up of ions. During an electrical impulse, the cell’s membrane becomes semi-permeable. Meaning, the cell’s membrane is partially opening up for exchange between ion to ion.

The Cardiac Muscles

The cardiac muscles are not voluntary. These muscles are involuntary. That means, we cannot control how the electrical impulses are firing in our heart. Our diet, the genetic makeup, hormones, and metabolic processes in our body dictates at what rate it should fire. Unlike other muscles, the cardiac muscles cannot be stimulated to contract. It has its own pace and race.

Refractory Period

During the refractory period, the heart cannot be stimulated but it goes back up again after the refractory period. The refractory period is essential for the survival of the heart. A refractory period is needed to prevent cardiac arrest. The electrical impulses of the heart are not only controlled by diet, genetic makeup, hormones, and metabolic processes in our body. The ions that electrical impulses get from potassium, calcium, and even sodium also has a say on how the firing rate would be.

The law of cardiac hemodynamics is saying that blood flows from a higher pressure chamber to a lower pressure chamber. The pressure responsible for this law is due to the presence of systole and diastole. Now, let us talk about the cardiac system and its pathways. The first initial activation of the systole prompts the atrioventricular valves to shut down. The result of this blockage is the stoppage of blood flow to your atrium. As the build of pressure heightens from both ventricle regions, blood is forced to be released down to your aorta. The initial rush of blood is fast and with a large volume of blood. Then as the arteries are neutralized, the pressure and the blood rush slowly ebbs away. The decrease in pressure lead down to a diastole state.

The diastole state signals the return of the initially gushed out blood. In this state, your ventricles are all relaxed and your valves are open. At the completion of this relaxed state, soon, the systole state will promptly begin. This state will be initiated by your SA node which fires electrical impulses. After firing such high electrical impulses, the pressure it will shoot right up high again. Then the cycle will start again and again. These processes all happen in milliseconds. The cardiac conduction system happens in just milliseconds because the cells in our body need the constant supply of nourishment and nutrients to feed themselves. Blood should always be distributed in a constant and rhythmic cycle.

The blood pumped out of the cardiovascular system and how is it fired is depending on the metabolic rate of cells and chemical processes in our body. The metabolic rate and chemical processes will, in turn, will be affected by the activities the individual is doing including his mental and psychological state. For example, if the person in the state of stress, the cardiac output might increase gradually and the pressure of the ventricles is always heightened to support the needed volume and firing of the blood out of the heart. Another example is if you are in the gym and you need an intense strenuous exercise for an hour. Your blood needs to be pumped quicker to all the cells in your blood as they too are working double-time to release energy. To be able to support your cell’s needs, the blood should be twice in volume and rate. Your heart knows when is it the time to pump harder through your nervous system’s commanding nerves. Impulses from your nervous system dictate when to slow down or fasten your heart rate.

Preload happens at the end of the diastole. The end of diastole signals the build of higher pressure for the pumping out process. During these times, the heart’s muscle fibers are stretched into their full potential. The amount of blood stored temporarily in the ventricles will be the volume that has to be released at the end of the diastole state. The preload state where the heart’s muscle fiber is stretched out to their full potential effects how much force is it going to be pumped out, out of your heart. Then at the end of the systole, your blood returns gradually to your heart. The action of returning blood in your heart also means that the muscle fibers of the heart are stretching out again to their full potential. The longer the muscle fibers are stretched the more potential for energy is gained and the more powerful is the pump at the end of the diastole.

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