Skeletal muscle performs several important functions within the human body. One of these is movement, which occurs when skeletal muscles attach to bones, against which they exert pressure to enable movement. Another function is to enable support and posture, this is due to the fact that skeletal muscles are rarely completely relaxed. I am in a constant state of slight contraction. Skeletal muscles also produce heat. This is because muscle contraction involves the production of glycogen breakdown to provide this energy, which in turn releases heat. This causes the body to overheat during physical activity. When our bodies are 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, known as the epimysium. to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an 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 provide shape and strength. The muscle belly is made up of numerous bundles of fibres, known as fatticuli, and are covered with perimysium. Each fiber within a fascicle is enclosed by a membrane, known as the sarcolemma. This contains many smaller fibers called myofibrils which provide the contractile unit of the muscle. These myofibrils are covered by endomysium and have striations that represent a sarcomere. Myofibrils are a collection of separate units connected together to form long filaments. These units are called sarcomeres and are the contractile units of the muscle. This pattern repeats along the length of the myofibril. yofibril. There are three different types of skeletal muscle fibers, which are: red/slow type I fibers “slow twitch fibers”; Type IIa red/fast fibers “fast oxidizing fibers”; White/fast fibers IIb “fast glycolytic fibres”. Each of these muscle fibers has different functions and characteristics that define them. The main characteristic of type I muscle fibers is that they have slow ATPase activity. They also have a high capacity to produce ATP 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 main way for the production of ATP is aerobic cellular respiration, the final stage of which is oxidative phosphorylation. Type 1 fibers also produce high levels of intracellular myoglobin. Due to this and the fact that the capillary networks are dense, their predominant color is red. Please note: this is just an example. Get a custom paper from our expert writers now. Get a Custom Essay The main characteristics of fast-twitch muscle fiber IIa are that they have higher myosin ATPase activity than type 1 muscle fibers. They also have a high capacity to produce ATP via oxidative phosphorylation. Their capillary network is also dense. These characteristics mean that the main way for the production of ATP is aerobic cellular respiration, the final stage of which is oxidative phosphorylation. They also have high levels of intracellular myoglobin. This also means, as with Type I, that their predominant color is red.