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Each one of these two parts is known as a "valve". The two valves are known as the "right valve" and the "left valve"; these are labeled with respect to the anterior end of the bivalve, when the umbones are facing upward. In many, but not all, bivalves, the two valves are more or less symmetrical and thus (other than the hinge line) look like ...
The two valves meet at a mobile hinge at the back of the body. In nearly all rhynchonelliforms, this hinge is strengthened by a pair of teeth on the ventral valve, fitting into a pair of sockets on the dorsal valve. This tooth-and-socket articulation is responsible for rhynchonelliforms' alternative name as articulated brachiopods.
A bivalve shell is the enveloping exoskeleton or shell of a bivalve mollusc, composed of two hinged halves or valves. The two half-shells, called the "right valve" and "left valve", are joined by a ligament and usually articulate with one another using structures known as "teeth" which are situated along the hinge line.
One of the simplest methods of assessing the heart's condition is to listen to it using a stethoscope. [1] In a healthy heart, there are only two audible heart sounds, called S1 and S2. The first heart sound S1, is the sound created by the closing of the atrioventricular valves during ventricular contraction and is normally described as "lub".
This is an accepted version of this page This is the latest accepted revision, reviewed on 11 December 2024. List of organ systems in the human body Part of a series of lists about Human anatomy General Features Regions Variations Movements Systems Structures Arteries Bones Eponymous Foramina Glands endocrine exocrine Lymphatic vessels Nerves Organs Systems Veins Muscles Abductors Adductors ...
Heart valves are opened or closed by a difference in blood pressure on each side. [1] [2] [3] The mammalian heart has two atrioventricular valves separating the upper atria from the lower ventricles: the mitral valve in the left heart, and the tricuspid valve in the right heart. The two semilunar valves are at the entrance of the arteries ...
The UK's NHS was using around 130,000 pagers in 2019, more than one in 10 of the world's pagers, according to the government. ... It said North America and Europe are the two biggest pager markets ...
The cardiac skeleton binds several bands of dense connective tissue, as collagen, that encircle the bases of the pulmonary trunk, aorta, and all four heart valves. [2] While not a traditionally or "true" or rigid skeleton , it does provide structure and support for the heart, as well as isolate the atria from the ventricles.