Skeletal Muscle Structure Skeletal muscle is a type of muscle that is responsible for voluntary movement. It is composed of bundles of muscle fibers called...
Skeletal Muscle Structure
Skeletal muscle is a type of muscle that is responsible for voluntary movement. It is composed of bundles of muscle fibers called muscle fibers or myofibrils. Each muscle fiber is covered by a layer of connective tissue called the sarcolemma. The sarcolemma helps to protect the muscle fiber and allows it to contract.
Muscle Contraction
When a skeletal muscle contracts, the myosin heads bind to actin filaments on the surface of the sarcolemma. This binding causes the myosin heads to rotate, which then pulls the actin filaments closer to the center of the muscle fiber. The contraction of the myosin heads also causes the myofilaments to slide past each other, which results in the stretching of the muscle fiber.
Muscle Relaxation
When a skeletal muscle relaxes, the myosin heads dissociate from the actin filaments. This causes the myosin heads to return to their original position, which is located far from the center of the muscle fiber. The relaxation of the myosin heads also causes the myofilaments to slide past each other in the opposite direction, which results in the shortening of the muscle fiber.
Factors Affecting Skeletal Muscle Contraction
There are a number of factors that affect skeletal muscle contraction, including:
Temperature: Skeletal muscle contraction is more efficient at higher temperatures.
Hormones: Hormones such as growth hormone and insulin-like growth factor-1 can stimulate skeletal muscle contraction.
Fatigue: When skeletal muscle is fatigued, it is more difficult to contract.
Training: Regular exercise can help to improve skeletal muscle strength and endurance