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Unformatted text preview: 0B X X X X X X X X X V V V I I I I I I . . . M M M u u u s s s c c c u u u l l l a a a r r r S S S y y y s s s t t t e e e m m m Â¡ The muscular system is the most important effector system; the information collected by the sensory systems and processed by the central nervous system is acted upon by muscles (we see something, we think about it, we run). The system is made primarily of contractile tissue, which has a single function: to contract or, in the absence of length change, to generate mechanical force. (We have also seen excitatory muscle tissue, Purkinje fibers, the HIS fibers of the heart muscle, but they are highly specialized and rare muscle cells.) 1B M M M u u u s s s c c c l l l e e e T T T y y y p p p e e e s s s 2B S S S m m m o o o o o o t t t h h h m m m u u u s s s c c c l l l e e e Smooth muscle is found in the internal organs such as the stomach, esophagus, sphincters, uterus, veins, and arteries. Smooth muscle is made of single cells arranged in sheets wrapped around the walls of the organ in question. The unique function of smooth muscle is to exert pressure on the contents of the organ and control the size of its lumen. The contraction is gradual and sustainable for long periods. 3B C C C a a a r r r d d d i i i a a a c c c m m m u u u s s s c c c l l l e e e The vertebrate heart is made of specialized muscle cells that are arranged in fibers....
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- Fall '08