Nerve cells transmit electrical signals. They are well suited to their function because:
Muscle cells bring parts of the body closer together. They are well suited to this function because:
There are different types of muscle cell, each perfectly adapted to its function:
Cardiac (heart) muscle cells are branched, and they join together to make a net. Cardiac muscle cells contract rhythmically, even outside the body. They never get tired.
Skeletal muscle is joined to bones. Its cells contract to make bones move and joints bend.
Smooth muscle cells make up thin sheets of muscle, such as the stomach lining. They can also be arranged in bundles, or rings, like that in the anus.