Skeletal muscle has several important functions in the human body. One of these is movement, which occurs when skeletal muscles attach to bones, which they pull against in order to allow movement. Another function is to provide support and posture, as skeletal muscles are rarely completely relaxed. They are in a constant state of slight contraction. Skeletal muscles also produce heat. This is because when muscles contract, it involves the production of broken down glycogen in order to provide this energy, which in turn releases heat. This causes the body to heat up when we exercise. When our body is cold, muscles often undergo a series of involuntary muscle contractions, which in turn release heat to help keep the body warm. Skeletal muscle is completely surrounded by thick connective tissue, called epimysium. Say no. to plagiarism. Get a tailor-made essay on “Why Violent Video Games Should Not Be Banned”? Get the original essay The epimysium is continuous and eventually forms tendons, which help connect muscles to bones. Each part of the muscle is covered in connective tissue, which helps give it shape and strength. The muscular belly is made up of numerous bundles of fibers, called fasciuli, and covered with perimysium. Each fiber in a fascicle is surrounded by a membrane called the sarcolemma. This contains many smaller fibers called myofibrils which constitute the contractile unit of the muscle. These myofibrils are covered in endomysium and have striations that represent a sarcomere. Myofibrils are a pattern of separate units linked together to form long strands. These units are called sarcomeres and are the contractile units of the muscle. This pattern repeats along the entire length of the myofibril. yofibril. There are three different types of skeletal muscle fibers, namely: red/slow type I fibers “slow twitch fibers”; Type IIa red/fast fibers “rapidly oxidizing fibers”; White/fast fibers IIb “fast glycoltic fibers”. Each of these muscle fibers has different functions and characteristics that define them. The main characteristics of type I muscle fibers are that they have slow ATPase activity. They also have a high capacity for ATP production via oxidative phosphorylation. Type I muscle fibers are also highly phosphorylated. Type I muscle fibers also have very dense capillary networks. Due to these three characteristics, the primary pathway for ATP production is aerobic cellular respiration, the final step of which is oxidative phosphorylation. Type 1 fibers also produce high levels of intracellular myoglobin. For this reason and the fact that the capillary networks are dense, their predominant color is red. Keep in mind: this is just a sample. Get a personalized article from our expert writers now. Get a Custom Essay The main characteristics of fast-twitch muscle fiber type IIa are those that have higher myosin ATPase activity than muscle fibers type 1. They also have a high capacity for ATP production via oxidative phosphorylation. Their capillary network is also dense. These characteristics mean that the main pathway for ATP production is aerobic cellular respiration, the final step of which is oxidative phosphorylation. They also have high levels of intracellular myoglobin. Which also means - as for type I - that their predominant color..