Process of muscle contraction - Essay Example

Process of muscle contraction The process of muscle contraction involves a series of biochemical reactions in the body of a living organism. The order of events leading to contraction is initiated in the central nervous system, as either voluntary activity from the brain or as reflex activity from the spinal cord. In this process of muscle contraction, motor neuron in the ventral horn of the spinal cord gets activated, followed by an action potential which passes outward in a ventral root of the spinal cord.

The axon branches to supply a number of muscle fibers called a motor unit, and the action potential is conveyed to a motor end plate on each muscle fiber. At the motor end plate, the action potential initiates the release of packets or quanta of acetylcholine into the synaptic clefts on the surface of the muscle fiber. Acetylcholine causes the electrical resting potential under the motor end plate to change, and this in turn initiates an action potential which passes in both directions along the surface of the muscle fiber.

The action potential spreads inside the muscle fiber at the opening of each transverse tubule onto the muscle fiber surface. At every point where a transverse tubule touches part of the sarcoplasmic reticulum, it causes the sarcoplasmic reticulum to release Ca++ ions which are critical in the overall contraction process. The last course of action calcium ions result in movement of troponin and tropomyosin on their thin filaments, and this enables the myosin molecule heads to “grab and swivel” their way along the thin filament.

This is the driving force of muscle contraction. Work cited Cardinale, Marco, Rob Newton, and Kazunori Nosaka. Strength and conditioning: biological principles and practical applications. Chichester, West Sussex, UK: John Wiley & Sons, 2011. Print.