Essential to adjust flow in human hearts and modern plumbing

noun

1. Any of numerous mechanical devices by which the flow of liquid, gas, or loose material in bulk may be started, stopped, or regulated by a movable part that opens, shuts, or partially obstructs one or more ports or passageways
2. A device in a brass instrument for quickly channeling air flow through an added length of tube in order to change the fundamental tone by some definite interval
3. Electron tube
4. A bodily structure (such as the mitral valve) that closes temporarily a passage or orifice or permits movement of fluid in one direction only
5. One of the distinct usually hinged and movable pieces of which the shell of some shell-bearing animals (such as lamellibranch mollusks, brachiopods, and barnacles) consists
6. One of the segments or pieces into which a dehiscing capsule or legume separates
7. The portion of various anthers (as of the barberry) resembling a lid
8. One of the two encasing membranes of a diatom
9. A leaf of a folding or double door

noun

1. A valve in which a ball regulates the aperture especially by its rise and fall due to fluid pressure, a spring, or its own weight

noun

1. Mitral valve

noun

1. A valve consisting of two semicircular clappers hinged to a cross rib that permits fluid flow in only one direction
2. A damper or valve in a pipe consisting of a disk turning on a bisecting axis

noun

1. A valve that permits flow in one direction only

noun

1. Safety valve

   "This dive watch's helium escape valve is conveniently located at 10 o'clock, so you and your watch can easily decompress as you surface."

noun

1. A cardiac valve consisting of two triangular flaps which allow only unidirectional blood flow from the left atrium to the left ventricle

noun

1. A valve (as for a steam boiler) that allows gas or liquid under excessive pressure to escape in a controlled manner
2. An outlet for pent-up energy or emotion
3. Something that relieves the pressure of overcrowding

noun

1. Either of two heart valves of which one occurs between the heart and the aorta and the other between the heart and pulmonary artery and that consist of three crescent-shaped flaps that are forced apart by pressure in the ventricles during systole and pushed together by pressure in the arteries during diastole and which prevent regurgitation of blood into the ventricles

noun

1. A valve that opens and closes a passageway by sliding over a port