skeletalmuskulatur

Skeletalmusculature, also known as voluntary or striated muscle, is a type of muscle tissue that is attached to bones and is responsible for voluntary movements. It is found throughout the body, with the largest concentration being in the limbs. Skeletal muscle is characterized by its striated appearance under a microscope, which is due to the arrangement of its contractile proteins, actin and myosin.

Skeletal muscle fibers are long, cylindrical cells that are multinucleated, meaning they contain multiple nuclei. This is because skeletal muscle fibers are formed by the fusion of multiple myoblasts during embryonic development. Each fiber is surrounded by a plasma membrane called the sarcolemma and contains numerous myofibrils, which are the contractile units of the muscle.

Skeletal muscle contraction occurs when an action potential travels along the sarcolemma and triggers the release of calcium ions from the sarcoplasmic reticulum. This calcium binds to troponin, causing a conformational change that exposes myosin-binding sites on actin. Myosin then binds to actin and undergoes a power stroke, pulling the actin filaments and causing the muscle fiber to shorten.

Skeletal muscle is innervated by motor neurons, which transmit signals from the central nervous system to the muscle fibers. The strength and duration of muscle contraction depend on the frequency and duration of these signals. Skeletal muscle also has a rich blood supply, which provides oxygen and nutrients necessary for contraction and recovery.

Skeletal muscle plays a crucial role in various physiological functions, including locomotion, posture, and manipulation of the environment. It is also involved in maintaining homeostasis, such as regulating body temperature and blood pressure. Skeletal muscle is a dynamic tissue that can adapt to changes in physical activity and nutrition, making it an important target for exercise and nutrition interventions.