Cellular Physiology of Muscle Cells part

Part III of this book describes the second major type of excitable cell: muscle cells. These cells are specialized to produce movement when they are electrically stimulated. Because muscle cells produce visible movements, their actions are the most obvious external manifestation of the activity of the nervous system. The point of interaction between the nervous and muscular systems the neuromuscular junction was the central focus for the discussion of chemical synaptic transmission in Chapter 8. In the first chapter of Part III, Chapter 10, we return to the neuromuscular junction and examine the sequence of events linking an action potential in the postsynaptic muscle cell to mechanical contraction. This linkage is the process called excitation-contraction coupling, and the explanation of this process in terms of underlying molecular mechanisms stands as one of the major accomplishments of cellular physiology. Chapter 11 then discusses how the nervous system controls the strength of contraction of an entire skeletal muscle by regulating the twitch contractions of the individual muscle cells making up the muscle. Chapter 12 considers the important electrical differences between the muscle cells of skeletal muscles and the heart. These electrical differences underlie the ability of the heart to produce the rhythmic, coordinated contractions necessary to pump blood through the body. The control of the heart by the autonomic nervous system is also considered in Chapter 12.

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