What are the four 'Principal Types of Tissues'?
1. Epithelial tissue (e-pa-fe-le-all) - covers and protects the body surface, lines body cavities, specializes in moving substances into and out of the body or particular organs (secretion, excretion, and absorption), forms many glands. Epithelial tissues are closely together with very little extracellular matrix. E.g. Outer Layer of skin, Glands of the body, Lining of the respiratory, digestive, urinary, reproductive tracts. p. 135
2. Connective Tissue - supports the body and it's parts, connects and holds them together, transport substances through the body, and protect it from foreign invaders. Cells in connective tissue often far apart and separated by large quantities of matrix. E.g. Bones, Joint cartilage, Tendons and ligaments, Blood, Fat.
3. Muscle tissue - produces movement, moves the body and it's parts. Muscle cells contract to make movement. Muscle tissue produces most of the heat of the body. E.g. Heart Muscle, Muscles all over the body.
4. Nervous tissue - may be most complex tissue in the body. Specializes in communication between various parts of the body and in integration of their activities. Major function is the generation of complex messages that coordinate the body functions. E.g. Tissue of the brain and spinal cord, nerves of the body, sensory organs of the body.