Final answer:
Animal muscle cells contract by generating their own action potential, often stimulated by nerve impulses. The contraction process involves the sliding of actin and myosin protein filaments within the cells, using energy from ATP.
Step-by-step explanation:
Animals, like muscle cells, go through a process of contraction. Muscle cells, or myocytes, are specialized for this purpose and are one of three types of muscle tissue found in the body; the other two being cardiac muscle and smooth muscle. These cells can create their own action potential and contract in response to nerve impulses. For example, muscle cells in the heart have characteristics of both nerves and muscles and can work in synchrony, which allows the heart to function effectively. During contraction, muscle cells utilize protein filaments, actin, and myosin, which slide past one another and use energy from ATP to facilitate movement and bodily processes such as respiration and digestion.