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3. Tissue
A tissue is a group of cells working together to do a special job A histologist is one who specializes in the study of tissues. The cells, of which the tissues are made, contain from 60 to 99 % water. Chemical reactions that are necessary for proper body function are carried on much more readily in a water solution. The water solution and other materials in which the tissues are bathed is slightly salty. It must be mentioned that an insufficiency of tissues fluid is called dehydration and an abnormal accumulation of this fluid caused a condition called edema.
Tissue classification: The 4 main groups of tissues are:
1) epithelial tissue forms elands, covers surfaces and lines cavities;
2) co
3) nerve tissue conducts nerve impulses all over the body;
4) the muscle tissue is designed for power-producing contractions.
The surface of the body and of the tubes or passages leading to the exterior and the surface of the various cavities in the body are lined by cells which are closely approximated to each other; thus have a small amount of intercellular substance. This lining cellular layer is called epithelium. The nature and consistency of intercellular substance, the matrix, and the amount and arrangement of fibers furnish the basis for the subdivision of co
The nervous system of higher animals is characterized by the multiplicity of cellular forms and intercellular co
Muscle tissue is composed of elongated cells which have the power of contracting or reducing their length. This property of contraction is ultimately a molecular phenomenon and is due to the presence of protein molecules. The following three types of muscle tissue occur in the body.
Smooth muscle tissue is found in sheet or tubes forming the walls of many hollow or tubular organs, for example the bladder, the intes tines of blood vessels. The cells forming this tissue are long spin dles with a central oval nucleus.
Striated muscle tissue is composed of cylindrical fibres often of great at length in which separate cells ca
liquid – жидкость
epithelial – эпителиальный
layer – слой
muscle – мышца
body – тело
flexible – гибкий
elastic – эластичный
nucleus – ядро
smooth – гладкий
fibre – волокно
cardiac – сердечный