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When we feel our own pulse pressing upward to our skin, we tend to picture the heart beating like a drum, pushing outward on each beat.
But the heartbeat is more like a squeezing or twisting than a thumping. It begins like this: Electricity from special cells (called pacemaker cells)-starting at the top of the heart and moving down-stimulates the heart muscle to squeeze the blood out through the aortic valve.
It's like wringing a wet towel to squeeze out the liquid. As the heart muscle becomes tightly wound, the blood is squeezed out until there is virtually no space between the individual muscle cells. The blood is then pushed through the valves. The wave of blood that has been squeezed out of the heart is ejected into the aorta itself, the body's largest artery, which carries oxygen-rich blood to the rest of the body.
Once that happens, the heart relaxes-as if your hands had just let go of the towel. As it does, the coronary vessels, which lie on the surface of the heart, also relax. Then the space between the tight muscle cells opens up, and the rich, oxygenated blood that was just ejected from the heart fills the arteries on the heart's surface and slips down between those cells and feeds them. Most of the ejected blood goes on to fuel the rest of the body-but not before the heart puts its own tax on it, taking its first cut of the life-sustaining fluid.
After the process of towel-wringing-squeezing blood into the aorta followed by muscle relaxation and the heart feeding itself-then, 60 or more times a minute, the pacemakers send out their next signal, beginning the process all over again.
The heart is divided into four chambers: the right atrium, the right ventricle, the left atrium and the left ventricle. Each chamber has a one-way valve at the exit that prevents blood from flowing backwards. When each heart chamber contracts, the valve at its exit opens. When the heart chamber is finished contracting, the valve closes so blood does not flow backwards.
The valve in each chamber has a name. The tricuspid valve is in the right atrium. The pulmonary valve is in the right ventricle. The mitral valve is in the left atrium. The aortic valve is in the left ventricle.
When the heart muscle contracts (or beats), it is pumping blood out of the heart. The heart contraction comes in two stages. During the first stage, the right and left atria contract simultaneously, pumping blood to the right and left ventricles. Then, it is the ventricles turn to contract together so they can propel blood out of the heart. After this, the heart muscle relaxes before the next heartbeat. This way, blood can fill up the heart again.
The heart's right side and left side have separate functions. The right side collects oxygen-poor blood from the body then pumps it to the lungs where it can pick up oxygen and release carbon dioxide. The left side then collects oxygen-rich blood from the lungs so it can pump it to the body so cells have the oxygen they need to function properly.
The heart has four chambers and four main vessels that pump blood into and out of the heart.
A wall, called the septum, divides the heart into the "right heart" and the "left heart." Each side is divided into an upper chamber, the atrium, and a lower chamber, the ventricle. The sides work together like a double pump.
With each heartbeat, the pump on the right side receives blood from the body and pumps it into the lungs to pick up oxygen. The pump on the left side receives this oxygen-rich blood from the lungs and pumps it throughout the body. The heart muscle then relaxes so the chambers can fill up with blood again and continue this process.
A system of valves ensures that blood flows in the right direction, in and out of the heart’s chambers.
The heart is an extremely well designed pump. In fact there are two pumps that are joined together to work in series. There is a right-sided pump that is responsible for pulling spent blood (blood that has already delivered its nutrients and oxygen) back from the tissues of the body. This blood enters the top chamber of the right heart, called the right atrium. This chamber squeezes when full and pushes its contents through a one way valve (the tricuspid valve) into the chamber below, the right ventricle. Once this chamber is full it squeezes or better said, it contracts. This forceful contraction sends blood through the pulmonic valve to the lungs, where it releases carbon dioxide and is filled with oxygen.
The second pump is known as the left heart. Once the blood sent off by the right ventricle passes through the lungs, it is gathered into the top chamber of the left heart, called the left atrium. Again, the chamber fills and squeezes it’s contents through a one way valve, known as the mitral valve. The blood passes through the mitral in ends up in the left ventricle, the most powerful chamber of the human heart. This chamber expands ands then forcefully expels the contents through the aortic valve and out to the entire body, via the aorta.
The heart is a miraculous pump. It works because it is mostly made of muscle. Each tiny cell is able to perform a contraction in one direction. In fact, if they are separated out and given appropriate nutrients, a microscope will allow you to see individual cells still beating! In the heart, those cells are connected together into bundles which contract in an organized fashion when stimulated by an electrical current moving through the heart with each beat. The heart has four chambers: two atria and two ventricles. The right heart contains the right atrium and the right ventricle. The veins of the body bring used blood back into the right atrium. This venous blood is low in oxygen and looks darker in color, since the oxygen has been partially extracted by the cells of the body. Next, the blood travels through the right ventricle and into the lungs. When the blood comes out of the lungs, it is brighter red since it has higher oxygen content. It enters the left atrium, then the left ventricle, and it is pumped out to the body. You can think of it as the right heart pumping oxygen-poor blood into the lungs and the left heart pumping oxygen-rich blood to the body. There are four major heart valves. The one-way valves between each atrium and ventricle prevent the blood from being pumped backwards as the ventricle contracts. There is also a valve at the outflow of each ventricle. Those prevent the blood which has already been pumped from being sucked back into the ventricles as they relax. Everyone knows the classic “lub-dub” heartbeat. These two sounds are the valves closing. With each “lub-dub”, or cardiac cycle, the two atria contract together, followed by contraction of the two ventricles. It’s mind-boggling to realize that, with all our technology, we haven’t even come close to creating a pump that can run for 80+ years so efficiently, reliably, and without resting!
The heart pumps blood through a coordinated series of contractions that send blood through the four chambers of the heart and on to the rest of the body. It’s an efficient system that begins with oxygen-depleted blood entering the right atrium. When it is full of blood, the atrium contracts, sending the blood into the right ventricle. During all of this, the four valves of the heart open and shut quickly to keep blood flowing in one direction only. From there, the blood is pumped through the pulmonary veins into the lungs.
At the same time, oxygen-rich blood is returning from the lungs to the heart and flows into the left atrium. The left atrium contracts, sending that blood into the left ventricle. From there, blood is pumped to the aorta, the main artery that carries blood, and it can now be distributed to the rest of the body’s organs and tissues.
The heart pumps blood by the creation of a vortex very similar to a tornado inside the heart. The vortex sucks blood into the left lower chamber (ventricle) and, when it reverses itself, ejects blood out through the aortic valve into the main blood vessel (aorta) for distribution to all parts of the body.
There is twisting and untwisting of the tip and base of the heart, which produces the vortex. It is very similar to how one would dry a wet towel using a wringing motion - holding the towel at two ends and then wringing it to dry the towel.
This concept has been validated in many studies. A technique called three-dimensional speckle tracking echocardiography can help detect this as can cardiac magnetic resonance imaging.
Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.