Muscle cells have the incredible ability to convert the chemical energy of adenosine triphosphate (ATP) into the mechanical energy of muscle contraction.
There are three main events that need to take place to allow contraction of skeletal muscle fiber:
Read and watch the following animation below to evaluate and interpret the process involved in the activation of the actin-myosin cross bridge (sliding filament mechanism) in skeletal muscle contraction.
Skeletal muscle fiber cells can be stimulated by a somatic motor neuron resulting in depolarization of the sarcolemma. If this depolarization reaches threshold, an action potential is initiated resulting in muscle contraction.
An action potential is transmitted along the sarcolemma and down the T tubules (transverse tubules). This action causes calcium ions to be released from the terminal cisternae of the sarcoplasmic reticulum. Calcium ions couple electrical excitation to muscle fiber contraction by binding to troponin.