Biological tissue is a collection of interconnected
cells that perform a similar function within an organism.The study of tissue is known as
histology, or, in connection with disease,
histopathology.The classical tools for studying the tissues are the wax block, the tissue stain, and the
optical microscope, though developments in
electron microscopy,
immunofluorescence, and frozen sections have all added to the sum of knowledge in the last couple of decades.With these tools, the classical appearances of the tissues can be examined in health and disease, enabling considerable refinement of clinical diagnosis and prognosis. There are four basic types of tissue in the body of all
animals, including the human body and lower
multicellular organisms such as
insects. These compose all the organs, structures and other contents.
Epithelium - Tissues composed of layers of cells that cover organ surfaces such as surface of the skin and inner lining of digestive tract: the tissues that serve for protection, secretion, and absorption.
Connective tissue - As the name suggests, connective tissue holds everything together. Connective tissue is characterized by the separation of the cells by an inorganic material, which is called
extracellular matrix.
Bone and
blood are connective tissues.
Muscle tissue - Muscle cells contain contractile filaments that move past each other and change the size of the cell. Muscle tissue also is separated into three distinct categories: visceral or
smooth muscle, which is found in the inner linings of organs;
skeletal muscle, which is found attached to bone in order for mobility to take place; and
cardiac muscle which is found in the heart.
Nervous tissue - Cells forming the
brain,
spinal cord and
peripheral nervous system.
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Les tissus sont le niveau d'organisation intermédiaire entre les
cellules et les
organes. Un tissu est un ensemble de cellules pas forcément identiques mais de même origine, regroupée en ensemble fonctionnel, c'est à dire concourant à une même fonction. Les tissus se groupent en
organes.
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Ein Gewebe ist eine Ansammlung gleichartig oder unterschiedlich
differenzierter Zellen einschließlich ihrer
extrazellulären Matrix (Interzellularsubstanz). Die Zellen eines Gewebes besitzen ähnliche oder gleiche Funktionen und erfüllen so in der Regel gemeinsam die Aufgaben des Gewebes.Mit dem Aufbau von Geweben befasst sich die
Histologie, bei krankhaften Veränderungen die Pathohistologie.Grundsätzlich lassen sich alle Anteile eines vielzelligen Organismus, das heißt alle Organe, Strukturen und sonstigen Inhalte von Tieren und Pflanzen, einem Gewebe zuordnen, beziehungsweise sind von einem Gewebetyp produziert worden.
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