do heart valves work:How the heart works

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The purpose of the heart is to pump the blood that bathes every organ of the body. The blood carries oxygen and nutrients to the tissues, and removes waste products from the tissues. If the pumping action of the heart is disrupted, the body’s organs begin to fail very quickly. Therefore, life itself is dependent on the efficient operation of the heart.
The heart muscle contracts in two stages to squeeze blood out of the heart. This is known as systole.
In the first stage, the upper chambers (atria) contract at the same time, pushing blood down into the lower chambers (ventricles). Blood is pumped from the right atrium down into the right ventricle and from the left atrium down into the left ventricle. In the second stage, the lower chambers contract to push this blood out of the heart to either the body via your main artery (aorta) or to the lungs to pick up oxygen.
The heart then relaxes – known as diastole. Blood fills up the heart again, and the whole process, which takes a fraction of a second, is repeated.
The different sides of the heart have different functions.

On the right side, the upper chamber fills with oxygen-depleted blood from your body and pushes it via the lower chamber and the pulmonary artery back to the lungs. Here blood picks up oxygen and releases carbon dioxide. On the left side, the upper chamber fills with oxygen-rich blood from the lungs. This is pumped via the lower chamber into the aorta and out to the body to provide cells with the crucial oxygen they need.
What makes the heart beat?
On average, most people have a heart rate of around 72 beats per minute at rest. This varies according to fitness, age, exertion and general health.
Each heart beat is triggered by an electrical pacemaker - a group of cells in the heart that have the ability to generate electrical activity. They cause electrical impulses to spread over the heart and make it contract.
The largest natural pacemaker of the heart is called the sinoatrial or SA node and is found in the right atrium. From it, specialised groups of cells that carry the electrical charge lead off to the rest of the heart.
Valves of the Heart
The schematic diagram below illustrates the four valves of the heart and how they are oriented within the heart. The heart valves in reality are not in this simplified orientation, but the diagram serves to show the valves and their relationship to each other.
The heart is generally thought of as having a right and left side. In reality, the heart is one organ and not divided into two separate organs. The heart is made up of four chambers, two on the right and two on the left. The chambers are known as atria and ventricles. Each side of the heart is composed of one atrium and one ventricle. The atria are the receiving chambers of the heart, receiving blood flowing back to the heart. The ventricles are the chambers of the heart that pump the blood out of the heart.
The valves of the heart are located within the chambers of the heart and are critical to the proper flow of blood through the heart. All of the valves, when functioning normally, act as one-way valves, allowing blood to flow either from one chamber to another, or allowing blood to flow out of the heart, in only one direction. The valves control the flow of blood through the heart by opening and closing during the contractions of the heart. The opening and closing functions of the valves are controlled by pressure differences generated within the heart, as well as some muscles located within the heart.
The four valves are known as:
The tricuspid valve The pulmonic or pulmonary valve The mitral valve The aortic valve heart chambers diagram,Human 3D Heart anatomy diagram
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