WHAT IS IT?

A valve is a natural structure or man-made device in a passageway, tube, vessel, or hollow organ that allows fluid or partly fluid contents to travel in one direction, but closes to prevent the flow of those contents in the opposite direction. For example, valves are present in veins (blood vessels that carry blood to the heart) and prevent blood from flowing away from the heart. Valves in veins and other structures of the body are membrane-like folds in the lining of the structure. A membrane is a thin layer of flexible tissue that covers something.

WHERE ARE THE MOST IMPORTANT VALVES?

The most important valves in the body are those in the veins and in the chambers (hollow, but not always empty spaces) of the heart. The reason why these valves are so important is because they make sure that blood flows in the direction needed. Without these valves, the heart would not be able to pump blood effectively and blood would not flow correctly throughout the body.

WHERE ARE SOME OTHER VALVES IN THE BODY?

Small valves are also present in the vessels of the lymphatic system. The lymphatic system is a system of vessels that drain lymph from all over the body back into the blood. Lymph is a milky fluid that contains proteins, fats, and white blood cells (which help the body fight off diseases). The muscular rings at the connection points between the stomach and the beginning of the small intestine, and between the small intestine and large intestine, are sometimes called valves. The intestine (small and large) is a tube-shaped structure that is part of the digestive tract. It stretches from an opening in the stomach to the anus (rear end) and occupies most of the lower parts of the belly.

It should be noted that the muscular rings between the stomach and the beginning of the small intestine and between the small and large intestine direct the flow of fluid but do not prevent the backwards flow of fluid. You may be wondering how these rings can be called valves if they do not prevent the backwards flow of fluid. The reason is that any formation or reformation of tissue, or flap-like structure, that resembles or acts like a valve is called a valve.

WHAT CAN GO WRONG WITH VALVES?

Sometimes, things go wrong with valves. For example, they can stop working correctly. If this happens, fluid will back up and go in the opposite direction when it is not supposed to. In other cases, valves can become to narrow. In the heart, either one of these problems can lead to heart failure. These problems are sometimes treated by valve replacement. When valves in the veins of the legs do not work properly, it can lead them to become swollen and distorted. This is known as varicose veins (also known as spider veins).

IS THERE ANY OTHER DEFINITION OF VALVE?

Yes. A valve can also be a mechanical device by which the flow of liquid is started, stopped, or altered by a movable part that opens, shuts, or partially closes one or more openings or passageways.

WHAT ELSE IS A VALVE KNOWN AS?

A valve is also known as a valva.

WHAT IS THE ORIGIN OF THE TERM, VALVE?

Valve comes from the Latin word "valva" meaning "folding door."