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- An electrical “wiring system” is responsible for causing the heart to beat. Each heartbeat is triggered by an impulse that starts in the sinus node, which is a group of cells in the wall of the right atrium. Special pathways of nerves carry the electrical impulses to the muscle cells in the atria and ventricles, setting the pace of the heartbeat.
www.ncbi.nlm.nih.gov/books/NBK279249/
Jun 6, 2023 · The heart provides the body’s organs and tissues with a constant supply of blood – and with it vital oxygen and nutrients. You can think of the heart as a central pump that keeps the blood circulating around the body. At rest, an adult heart beats about 60 to 80 times a minute.
- 2023/06/06
The heart's pumping action is regulated by an electrical conduction system that coordinates the contraction of the various chambers of the heart. How does the heart beat? An electrical stimulus is generated by the sinus node (also called the sinoatrial node, or SA node).
Mitral or bicuspid valve is the valve that separates the left atrium and ventricle. Sino-atrial node (SA node) and atrioventricular node (AV node) are the two nodal tissues present in the human heart and it is mainly involved in helping the heart to produce its own action potential (impulses).
- Overview
- The heart’s chambers
- The heart’s valves
- Blood flow through the heart
- The heart’s crown
Your heart
The human heart is one of the hardest-working organs in the body.
On average, it beats around 75 times a minute. As the heart beats, it provides pressure so blood can flow to deliver oxygen and important nutrients to tissue all over your body through an extensive network of arteries, and it has return blood flow through a network of veins.
In fact, the heart steadily pumps an average of 2,000 gallons of blood through the body each day.
The heart’s four chambers function as a double-sided pump, with an upper and continuous lower chamber on each side of the heart.
The heart’s four chambers are:
•Right atrium. This chamber receives venous oxygen-depleted blood that has already circulated around through the body, not including the lungs, and pumps it into the right ventricle.
•Right ventricle. The right ventricle pumps blood from the right atrium to the pulmonary artery. The pulmonary artery sends the deoxygenated blood to the lungs, where it picks up oxygen in exchange for carbon dioxide.
•Left atrium. This chamber receives oxygenated blood from the pulmonary veins of the lungs and pumps it to the left ventricle.
•Left ventricle. With the thickest muscle mass of all the chambers, the left ventricle is the hardest pumping part of the heart, as it pumps blood that flows to the heart and rest of the body other than the lungs.
The heart has four valves, one each at the downstream end of each chamber, so that, under normal conditions, blood can’t flow backward, and the chambers can fill with blood and pump blood forward properly. These valves can sometimes be repaired or replaced if they become damaged.
The heart’s valves are:
•Tricuspid (right AV) valve. This valve opens to allow blood to flow from the right atrium to the right ventricle.
•Pulmonary valve. This valve opens to allow blood to flow from the left ventricle into the pulmonary artery to the lungs, so that the heart and rest of the body can receive more oxygen.
•Mitral (left AV) valve. This valve opens to let blood flow from the left atrium to the left ventricle.
•Aortic valve. This valve opens to let blood leave the left ventricle so that the blood can flow to the heart and the rest of body, save the lungs.
When working properly, deoxygenated blood coming back from organs, other than the lungs, enters the heart through two major veins known as the vena cavae, and the heart returns its venous blood back to itself through the coronary sinus.
From these venous structures, the blood enters the right atrium and passes through the tricuspid valve into the right ventricle. The blood then flows through the pulmonary valve into the pulmonary artery trunk, and next travels through the right and left pulmonary arteries to the lungs, where the blood receives oxygen during air exchange.
On its way back from the lungs, the oxygenated blood travels through the right and left pulmonary veins into the left atrium of the heart. The blood then flows through the mitral valve into the left ventricle, the heart’s powerhouse chamber.
The blood travels out the left ventricle through the aortic valve, and into the aorta, extending upward from the heart. From there, the blood moves through a maze of arteries to get to every cell in the body other than the lungs.
The structure of the heart’s blood supply is called the coronary circulatory system. The word “coronary” comes from the Latin word meaning “of a crown.” The arteries that fuel the heart’s muscle encircle the heart like a crown.
Coronary heart disease, also called coronary artery disease, typically develops when calcium containing cholesterol and fat plaques collect in and hurt the arteries that feed the heart muscle. If a portion of one of these plaques ruptures, it can suddenly block one of the vessels and cause the heart muscle to begin to die (myocardial infarction) because it’s starved for oxygen and nutrients. This can also occur if a blood clot forms in one of the arteries of the heart, which can happen right after a plaque rupture.
Mar 24, 2022 · Your heartbeat is the contraction of your heart to pump blood to your lungs and the rest of your body. Your heart's electrical system determines how fast your heart beats.
Your heart is made up of 3 layers of muscle tissue: pericardium, a thin, outer lining that protects and surrounds your heart; myocardium, a thick, muscular middle layer that squeezes (contracts) and relaxes to pump blood out of the heart to the rest of your body
Mar 24, 2022 · The pulmonary valve separates the right ventricle and the pulmonary artery. The aortic valve separates the left ventricle and aorta. The valves open and shut in time with the pumping action of your heart's chambers. The opening and closing involve a set of flaps called cusps or leaflets.
