Question

Describe the steps necessary for skeletal muscle contraction. Your answer should begin with the reception of the neural transmission at the muscle fiber and end with specific mineral uptake into the sarcoplasmic reticulum (relaxation).

Answer 1

• Action potential arises in a motor neuron which initiates Ca2+ ions release from the sarcoplasmic reticulum
• Ca2+ ions get bound to troponin present on actin leading to movement of tropomycin. The binding sites for the myosin heads are exposed.
• A crossbridge is formed between actin filaments and myosin heads which is dissociated by ATP
• The hydrolysis of ATP causes movement of myosin heads to spin and change alignment.
• Pivoted myosin heads get bound to the actin filament earlier returning to their original configuration.
• The relocation of the myosin heads towards the actin filaments at the middle of the sarcomere.
• The gliding of actin with myosin consequently curtails the sarcomere, leading to muscle contraction.
• The uptake of magnesium ions speeds up the process of muscle contraction.