Quadriceps femoris muscle

when the muscles of the quadriceps femoris group contract, they expand the knee joint, straightening the leg.



How perform the bones of the person skeleton move? Skeletal muscle contract and relax come mechanically relocate the body. Messages from the concerned system cause these muscle contractions. The whole process is dubbed the mechanism of muscle contraction and also it deserve to be summary in three steps:

(1) A blog post travels indigenous the nervous system to the muscular system, triggering chemistry reactions.

You are watching: Skeletal muscles need nerve stimulation for contraction to occur

(2) The chemistry reactions result in 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 longer present, the chemical process reverses, and the muscle fibers rearrange again and the muscle relaxes.

Let’s look a little more closely at the actions in the system of muscle contraction.

1. A Muscle convulsion Is Triggered when an activity Potential Travels follow me the Nerves to the Muscles


Muscle contraction starts when the nervous mechanism generates a signal. The signal, an impulse dubbed an activity potential, travels with a kind of nerve cell dubbed a motor neuron. The neuromuscular junction is the surname of the ar where the motor neuron reaches a muscle cell. Skeletal muscle tissue is composed of cells referred to as muscle fibers. When the nervous system signal reaches the neuromuscular junction a chemical message is exit by the motor neuron. The chemistry message, a neurotransmitter referred to as acetylcholine, binding to receptors on the outside of the muscle fiber. That starts a chemical reaction in ~ the muscle.

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


A multistep molecular process within the muscle fiber begins when acetylcholine binds to receptors on the muscle fiber membrane. The proteins inside muscle fibers are organized into long chains that can interact with every other, reorganizing come shorten and relax. Once acetylcholine reaches receptor on the membranes of muscle fibers, membrane networks open and also the process that contract a serene muscle yarn begins:

Open channels allow an flow of salt ions into the cytoplasm of 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 ion diffuse right into the muscle fiber.The relationship in between the chains of proteins in ~ the muscle cells changes, resulting in the contraction.

3. Muscle yarn Relax when the Nervous mechanism Signal Is No much longer Present


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

See more: What Was Invented In England By Rowland Hill In 1837? ? The Postage Stamp

External Sources

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

An evaluation of evidence in support of the sliding filament theory. College of Tennessee, Knoxville: The academy for eco-friendly Modeling. Http://www.tiem.utk.edu/~gross/bioed/webmodules/muscles.html

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