Next we have muscle tissue.
Muscle tissue is a special type of cell that unlike the cell types already described are deemed to be an “excitable” tissue. Meaning that they function by generating electrical currents within the tissue to perform the function of the tissue. In this way, all muscle tissue, regardless of the distinct type will exhibit the following qualities: irritability, extensibility, elasticity, and contractility. Each one of these qualities provides the foundation for the difference in physiology of the muscle tissue.
While all muscles may have the same function, there are three (3) different types of muscle cells that are recognized in the human body. This recognition is noted by the presence of (striated) or lack of organized intracellular structures (smooth) referred to transverse tubules (T-tubules). Within this typing of cells striated muscle tissues are additionally given names based on where in the body they are located (skeletal or cardiac) in the body, figure 15. Histologically striated (skeletal) muscle is a poly-nucleated (having more than 1 nucleus) cell with elongated striated muscle that attach to the skeletal structures via tendons and with nervous system stimulation allow for movement to occur. While smooth muscle is amorphic (no regular shape) muscle tissue with no visible striations that form a ring of muscle tissue surrounding lumens and organs of the body. Within the smooth muscle, the contractile proteins are arranged in the spiral to the long axis of the cell as opposed to cylinders that parallel the long axis seen in the skeletal and cardiac muscle. Lastly the cardiac muscle is a “Y-shaped” striated muscle that forms a network of overlapping muscle tissue connected with intercalated disks to all for coordination of muscle contraction.
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