Who circulates the blood to the body? the heart. The heart is a pump that works non-stop. In fact, it includes two pumps: one is on the right side, and the other is on the left. The heart is equipped with a wonderful electrical system thanks to which it beats on its own
Written by: Zvi Atzmon, Young Galileo
The blood is a liquid that allows the transportation of materials, immune system cells and heat in the body. In order for the blood to perform this vital process, it must flow. The blood is pumped by a pump that is in the chest and works non-stop all our lives - the heart.
The heart creates pressure on the blood
The heart, like any pump that pumps fluid, needs to create pressure. This pressure pushes the blood from the heart to the different parts of the body through the arteries. The heart creates pressure on the blood inside it when it contracts. The contraction is done by the heart muscle, a special muscle found in the walls of the heart. It is a very strong, involuntary muscle that works non-stop all our lives.
The heart is not one blood pump but two, working in a coordinated manner. One is the left side of the heart, and the other is the right side. The two pumps are separated by a septum that prevents the blood from passing from one side of the heart to the other.
One-way passage
Each side of the heart is divided into two spaces that contain blood: an atrium and a ventricle. Between rising to the room there is a passage of blood; This is a one-way passage - from the upstairs to the room. The flow of blood from the ventricle to the ventricle is done through a special valve, which allows blood to flow from the ventricle to the ventricle and prevents backflow.
A thin layer (endothelium) separates the heart muscle from the chambers of the heart through which blood flows. The entire heart is contained within a shell (the pericardium) whose walls are made of two layers: the inner layer is the outermost tissue of the heart itself.
the coronary arteries
The cells of the heart muscle need a constant blood supply. The reference is not to the blood flowing through the cavities of the heart, but to the blood that needs to reach the vicinity of each and every cell in the heart muscle. Indeed, the heart muscle is penetrated by arteries that carry blood to the muscle cells. These arteries surround the heart and are called coronary arteries.
dictate the pace
The heart is equipped with a wonderful electrical system called the electrical operating and conduction system. Thanks to her, the heart beats on its own. This system has a group of pacemaker cells located in the wall of the right atrium. These cells are called pacemaker cells because they activate the heart and dictate the rhythm of its beats.
These cells create electrical signals, like warning signs flashing on the side of the road at night. Every period of time (a little less than a second) they create an electrical signal. This electrical signal spreads very quickly to all the muscle cells of the elevators. As a result, the cells of the atria are activated, the atria contract, the pressure in them increases and the blood is pumped from them, through the valves, into the ventricles.
At exactly the same time the signal of the rhythm is enough to reach through electrically conductive cells to the ventricles. The muscle cells in the walls of the ventricles are activated, the muscles in the walls of the ventricles contract, and the pressure in them increases. Since the valves are one-way, the blood cannot go back up, and continues through arteries that carry blood from the chambers of the heart to the body.
pulsating on its own
When the heart rate produces electrical signals at a higher frequency, the heart beats faster. This happens during exertion such as running or during excitement. How does the heart rate know to increase the rate when we exert ourselves or get excited? Information about this comes to him from the nervous system, from the brain.
The one that activates the heartbeat is the natural heartbeat in the heart. The brain can only speed up or slow down the action of the rhythm. This fact explains how it is possible to transplant a heart from a donor: the transplanted heart continues to beat on its own as long as the heart itself is alive, even when the heart donor is no longer alive.
When the ventricles of the heart contract, the blood is pumped through special valves into the arteries. In the places where the arteries are close to the skin, you can feel a wave of blood coming following each beat. These blood waves are called a pulse, and they are used for a simple measurement of the heartbeat rate. The heart rate in children is usually higher than the heart rate in adults.
Did you know?!
If the action of the heart is the flow of blood into the arteries, and it includes electrical activity and the activity of muscle cells, why do we attribute our emotions to the heart? Why is love expressed in the illustration of a heart (which, by the way, is different from the real heart shape)? The answer is that the one who instills feelings and excitement in us is the brain, but it is "shy", and does not testify to us about its activity. However, when it creates excitement in us, the heartbeat increases - and we are certainly aware of this, and therefore associate emotions and excitement with the heart.
Did you know?!
The heart starts beating a few months before we are born. You can hear the heartbeats in the fetus, and even see them using a suitable imaging device.
From Young Galileo - the monthly for curious children, issue 206 March 2021
Join us on Facebook https://www.facebook.com/YoungGalileo
