Adenosine triphosphate (ATP) is considered by biologists to be the energy currency of life. It is the high-energy molecule that stores the energy we need to do just about everything we do.
The basic function of muscle is to generate force. Secondarily, muscles can provide some shape and form to the organism. Anatomically and functionally, muscle can be divided into two types, smooth and striated. Striated or striped muscle can be further divided into skeletal muscle and cardiac (heart) muscle.
The cell membrane of a muscle cell is called the sarcolemma, and this membrane, like that of neurons, maintains a membrane potential. So, impulses travel along muscle cell membranes just as they do along nerve cell membranes. However, the 'function' of impulses in muscle cells is to bring about contraction. To understand how a muscle contracts, you need to know a bit about the structure of muscle cells. Skeletal muscle is the muscle attached to the skeleton.