Body (organism): structure, parts, and meanings
A body is the physical form of an organism — its cells, tissues and organs — and the term also appears in specialized senses (plant body, cell body, corpse) and in nonbiological phrases.
Overview
The term body most commonly denotes the physical, organized material that makes up an individual organism: the ensemble of cells, tissues and organs that together perform life functions. In multicellular life the body is the integrated form that results when many cells differentiate, connect and coordinate. For some life forms that alternate between single-celled and multicellular phases, such as certain slime moulds, the word body is usually applied to the multicellular stage rather than the solitary cell stage. Physical material and organismic identity are closely linked in discussions of bodies.
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Parts and levels of organization
Bodies are built from hierarchical levels of organization. Cells form tissues; tissues form organs; organs form systems that maintain the whole. At the single-cell level the phrase cell body refers to the region that contains the nucleus and most metabolic machinery, for example in neurons that also have long axons. The location of the nucleus within a cell is often called the nuclear region or soma.
In multicellular animals the external and internal regions are often named by convention. The human body, as an accessible example, contains a head (head), neck, trunk or torso, two upper limbs (arms) and two lower limbs (legs). Primary reproductive structures differ between typical males and females, though sexual characteristics vary across individuals and species.
Types and special terms
Different contexts use distinct terms for bodies. A dead human body is often called a corpse or cadaver, while the remains of animals — especially vertebrates and large invertebrates — may be referred to as a carcass. The state of being dead transforms physiological processes and commonly changes legal and cultural treatment of the body. For plants, the phrase plant body describes the organized parts of a plant such as roots, stems and leaves, which differ in form and function from animal bodies.
Development, function and study
Bodies develop through embryological processes in many species, where cell division, differentiation and morphogenesis produce organs and the overall form. Once formed, bodies maintain internal equilibrium (homeostasis) through coordinated actions of systems such as the circulatory, nervous and digestive systems. The scientific study of body structure is typically called anatomy, while the study of how body parts work is physiology. More integrative disciplines examine growth, development and disease.
Common uses, examples and distinctions
The word body also appears in several figurative or specialized senses. In geology and hydrology one can speak of a body of water to mean a lake or reservoir, and in law the term body of law denotes a collection of statutes or principles. Linguistic histories and etymologies of the word are discussed in lexicons and dictionaries (word origin). Scientific and everyday usage distinguish between a living body and other senses; for instance, the term vertebrate body implies a backbone-supported structure, whereas many insects have segmented external skeletons.
Further reading and resources
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AlegsaOnline.com Body (organism): structure, parts, and meanings Leandro Alegsa
URL: https://en.alegsaonline.com/art/12625