Final answer:
The main differences between skeletal and cardiac muscle are the way they are stimulated to contract, the arrangement of actin and myosin proteins, and the role of ATP and calcium in contraction and relaxation.
Step-by-step explanation:
The main difference between skeletal and cardiac muscle is the way they are stimulated to contract.
In skeletal muscle, each muscle cell must be stimulated by a neurotransmitter, such as acetylcholine, to contract.
On the other hand, cardiac muscle contractions are stimulated by internal pacemaker cells that regularly contract and propagate contractions to other muscle cells they are in contact with.
Another difference is the arrangement of actin and myosin proteins.
Both skeletal and cardiac muscle have actin and myosin arranged in sarcomeres, which are the functional units of muscle contraction.
Lastly, contraction and relaxation in both skeletal and cardiac muscle require ATP for energy.
Calcium also plays a role in both types of muscle, as it binds to troponin to initiate muscle contraction.