Organs

In biology, an organ or viscus is a collection of tissues joined in a structural unit to serve a common function.In anatomy, a viscus is an internal organ, and viscera is the plural form.

Organs are composed of main tissue, parenchyma, and “sporadic” tissues, stroma. The main tissue is that which is unique for the specific organ, such as the myocardium, the main tissue of the heart, while sporadic tissues include the nerves, blood vessels, and connective tissues. The main tissues that make up an organ tend to have common embryologic origins, such as arising from the same germ layer. Functionally related organs often cooperate to form whole organ systems. Organs exist in all higher biological organisms, in particular they are not restricted to animals, but can also be identified in plants. In single-cell organisms like bacteria, the functional analogue of an organ is called organelle.

A hollow organ is a visceral organ that forms a hollow tube or pouch, such as the stomach, intestine, or bladder.

78 organs have been scientifically validated in the human body: men have 71 organs, women have 75 and hermaphrodites (intersex) can have 78.

Etymology

The English word “organ” derives from the Latin organum, meaning “instrument”, itself from the Greek word ὄργανον,órganon (“implement; musical instrument; organ of the body”). The Greek word is related to ἔργον, érgon (“work”). The viscera, when removed from a butchered animal, are known collectively as offal. Internal organs are also informally known as “guts” (which may also refer to the gastrointestinal tract), or more formally, “innards”.

Aristotle used the word frequently in his philosophy, both to describe the organs of plants or animals (e.g. the roots of a tree, the heart or liver of an animal), and to describe more abstract “parts” of an interconnected whole (e.g. his philosophical works, taken as a whole, are referred to as the “organon”).

The English word “organism” is a neologism coined in the 17th century, probably formed from the verb to organize. At first the word referred to an organization or social system. The meaning of a living animal or plant is first recorded in 1842.Plant organs are made from tissue built up from different types of tissue. When there are three or more organs it is called an organ system.

The adjective visceral, also splanchnic, is used for anything pertaining to the internal organs. Historically, viscera of animals were examined by Roman pagan priests like the haruspices or the augurs in order to divine the future by their shape, dimensions or other factors. This practice remains an important ritual in some remote, tribal societies.

The term “visceral” is contrasted with the term “parietal”, meaning “of or relating to the wall of a body part, organ or cavity”.The two terms are often used in describing a membrane or piece of connective tissue, referring to the opposing sides.