Integument (zoology)
The integument (Latin: integumentum "cover", "shell", "outer skin") describes the outer body shell of all tissue animals that is differentiated from the rest of the tissue . The term does not imply an anatomical, but a functional consideration.
Functions
In its basic function, an integument has to fulfill two functions that have opposing requirements. On the one hand, the organism must be protected against external influences such as B. offer mechanical loads and an unsuitable chemical environment ( homeostasis ), on the other hand it must ensure the contact of the organism with the outside world. Numerous groups of organisms have converged to each other and developed a stable mechanical outer shell in which sensory organs and glands of different functions are embedded. In numerous groups of organisms, gas exchange (breathing) also takes place via the integument. These organisms have a permanently moist body surface. Thereby diffuses the oxygen from the air through the moist surface of the body into the body interior into it and at the same time diffuses carbon dioxide from the inside to the outside. The arthropods have this special organs, the trachea , developed invaginations of the integument present inside the body.
In addition to these basic functions, the integument has a multitude of special functions in numerous groups of organisms. Color patterns and other special formations of the vertebrate skin are used for B. as a signal for social communication (e.g. gender identification and recognition). In numerous animal species, the integument to protect against enemies is reinforced like an armor (in vertebrates: osteoderm ), it can also develop attachments such as poison glands , thorns and spines. Dandruff, hair and feathers with their diverse functions are also special forms of the integument.
Other functions of the integument, e.g. B. in the endocrine system and immune defense , have only been better researched for a few years.
anatomy
Anatomically, integuments consist of a multitude of tissue types of very different shape, origin and complexity, depending on the organism group. The simplest form is a shell made of a single layer of differentiated cells. This is usually called the epidermis . An epidermis is a special case of covering tissue or epithelium . It occurs even in original tissue animals with only two cotyledons (diploblasts) such. B. the cnidarians . The integument emerges here from the outer cotyledon or ectoderm . In numerous anatomically more complex organisms such as B. in vertebrates, the mesoderm is also involved in the formation of integuments.
The integument of vertebrates , including humans, is called the skin . It consists of connective tissue ( dermis ) and the upper skin ( epidermis ) as well as skin appendages. Fibers of the structural protein keratin are an important component . The integument of the arthropods forms a very complex exoskeleton that is separated from the epidermis to the outside . In addition to numerous proteins, the nitrogen-containing polysaccharide chitin is one of the main components.
Web links
literature
- Hynek Burda : General Zoology. Eugen Ulmer, Stuttgart 2005, ISBN 3-8252-2690-5 , p. 155
- CM Chuong, BJ Nickoloff, PM Elias, LA Goldsmith, E. Macher, PA Maderson, JP Sundberg, H. Tagami, PM Plonka, K. Thestrup-Pederson, BA Bernard, SchröJ. M. der, P. Dotto, CM Chang, ML Williams, KR Feingold, LE King, AM Kligman, JL Rees, E. Christophers: What is the 'true' function of skin? In: Experimental Dermatology , 2002; 11: 159-187. doi : 10.1034 / j.1600-0625.2002.00112.x
- Harvey B. Lillywhite: Water relations of tetrapod integument. In: Journal of Experimental Biology. 209, 2006 pp. 202-226. doi : 10.1242 / jeb.02007
- Rene Solid Scratch; Donna Rae Siegfried. Biology for dummies. Gas exchange via the integument, p. 268f. Weinheim 2011