Quadriceps femoris muscle

once the muscle of the quadriceps femoris group contract, they prolong the knee joint, straightening the leg.



How perform the skeleton of the human skeleton move? Skeletal muscles contract and relax to mechanically relocate the body. Messages from the worried system cause these muscle contractions. The whole procedure is referred to as the device of muscle contraction and also it can be summarized in 3 steps:

(1) A article travels native the nervous mechanism to the muscular system, triggering chemistry reactions.

You are watching: A motor neuron transmits the effect of a nerve impulse to the muscle fiber at a

(2) The chemical reactions bring about the muscle fibers reorganizing themselves in a way that shortens the muscle--that’s the contraction.

(3) as soon as the nervous mechanism signal is no much longer present, the chemical procedure reverses, and the muscle yarn rearrange again and also the muscle relaxes.

Let’s look a little an ext closely in ~ the steps in the mechanism of muscle contraction.

1. A Muscle convulsion Is Triggered as soon as an action Potential Travels along the Nerves come the Muscles


Muscle contraction starts when the nervous system generates a signal. The signal, one impulse called an activity potential, travels with a kind of nerve cell referred to as a engine neuron. The neuromuscular junction is the name of the ar where the engine neuron get a muscle cell. Bones muscle organization is composed of cells referred to as muscle fibers. Once the nervous mechanism signal get the neuromuscular junction a chemical article is released by the motor neuron. The chemistry message, a neurotransmitter referred to as acetylcholine, binds to receptors on the external of the muscle fiber. That starts a chemistry reaction within the muscle.

2. Acetylcholine Is Released and also Binds to receptor on the Muscle Membrane


A multistep molecular process within the muscle fiber starts when acetylcholine binds to receptor on the muscle fiber membrane. The proteins inside muscle fibers room organized right into long chains that can communicate with each other, reorganizing come shorten and also relax. Once acetylcholine reaches receptors on the membranes of muscle fibers, membrane networks open and also the procedure that contract a tranquil muscle fibers begins:

Open channels permit an influx of salt ions right into the cytoplasm the the muscle fiber.The salt influx likewise sends a blog post within the muscle fiber to cause the release of save on computer calcium ions.The calcium ions diffuse right into the muscle fiber.The relationship between the chains of proteins within the muscle cell changes, resulting in the contraction.

3. Muscle yarn Relax as soon as the Nervous system Signal Is No much longer Present


When the stimulation the the engine neuron providing the advertise to the muscle yarn stops, the chemistry reaction that causes the rearrangement that the muscle fibers" proteins is stopped. This reverses the chemical processes in the muscle fibers and also the muscle relaxes.

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External Sources

A summary of skeleton muscle structure, including thick and also thin filaments of sarcomeres. University of Houston: department of Health and also Human Performance. Http://grants.hhp.coe.uh.edu/clayne/6397/unit3.htm

An analysis of proof in assistance of the sliding filament theory. University of Tennessee, Knoxville: The academy for eco-friendly Modeling. Http://www.tiem.utk.edu/~gross/bioed/webmodules/muscles.html

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