Muscle is composed of 75% water, 20% protein, and 5% minerals salts, glycogen and fat.
3 types of muscle
1. Skeletal – the muscle involved with movement. This muscle is under voluntary control, and attach to, and cover over, the bony skeleton
Examples: Quadriceps in the front of the upper legs, and the biceps brachii in the front upper arm
2. Cardiac – Cardiac muscle is an extremely specialized form of muscle tissue that has evolved to pump blood throughout the body. In fact, cardiac muscle is only found in the heart and makes up the bulk of the heart’s mass.
3. Smooth – Smooth muscle generally forms the supporting tissue of blood vessels and hollow internal organs, such as the stomach, intestine, and bladder.
It is considered smooth because it does not have the microscopic lines (the striations) seen in the other two types of muscle.