P4 – Describe the three structures of the skeletal muscle (Epimysium, Perimysium and Endomysium) There are three structures of the skeletal muscle: Epimysium is a thick layer of irregular connective tissue that pulls the entire muscle as well as protecting the muscle from friction that may be caused by other muscles and bones surrounding them. Also, it is the fibrous tissue which covers and surrounds skeletal muscles. The Epimysium carries on past the end of bones in order to create muscle tendons. Perimysium surrounds a bundle of muscle fibres, it is a casing of connective tissue. Endomysium is found within a muscle and it contains nerves and capillaries. It is a fine layer of connective tissue that extracts each individual myocyte. P5 – Describe the sliding filament theory, giving a step by step process. …show more content…
As muscle contractions occur they myosin filaments bind and attach to the actin filaments Myofibril is the contractile threads found in striated muscle cells and a segment of myofibril is called a sarcomere. The role of the sarcoplasmic reticulum is storing calcium ions, as well as releasing calcium ions during muscle contractions and reabsorbing calcium ions when the muscles relax. Actin is a protein that forms the thin filament in muscle cells. Thin filaments are made up of two long chains of actin molecules that are twisted around one another. Each actin molecule has a myosin-binding site where a myosin head can bind during the process of the sliding filament theory. Myosin is a protein that generates the force in a muscle contraction. Tropomyosin is a long strand. It loops around the actin chains in the thin filament. It covers the myosin binding site of the actin and tropomyosin molecules and prevents muscle