Skeletal Muscle Fibers

The Science Of Your Muscles

The skeletal muscles are used mainly to create movement, by applying force to joints and bones; via contraction . They contract voluntarily (via somatic nerve stimulation), although they can also contract involuntarily through reflexes, and are controlled by the somatic nervous system; whereas the autonomic nervous system controls the involuntary muscles. The Cholinergic System includes a series of neurochemicals that derive from choline, the basic building block to neurotransmitter acetylcholine, which facilitates the neuromuscular junction. In order for the brain to send signals to the muscles for muscle contraction, acetylcholine passes from nervous tissue to muscular tissue through the neuromuscular junction.[6] Muscle function is maintained by ion channels that transport ions — including chloride, sodium, potassium and calcium — and are essential for controlling muscle excitation and contraction and are important to sustain NMJ and nerve integrity.[2] Involuntary muscles consist of muscles that line your internal organs and the blood vessels. Muscles in the skeletal system are organized into extrafusal and intrafusal fibers. Extrafusal fibers are the strongest, outer layers of muscle.

Skeletal muscles are considered voluntary muscles which mean you have to first think of contracting them and the nervous system tells them to react. The Public Library Of Science say that “in most mammals, skeletal muscle comprises about 55% of individual body mass and plays vital roles in locomotion, heat production during periods of cold stress, and overall metabolism.” [7] They also perform two kinds of contractions. Skeletal muscles are nearly always dependent on each other in order to perform everyday tasks. For example, imagine someone who has biceps, but doesn’t have any opposing muscles (triceps) to counteract the bending motion of their biceps.

Muscles are bundles of contractile fibers that are organized in a normal pattern, so that under a microscope they appear as stripes (hence, they are also called striated or striped muscles). A Pluripotent cell can turn into pretty much any cell. These cells behave in a similar way to embryonic stem cells, so they could be useful for developing a range of therapies.[3] The Nobel Prize-winning technology emerged from the lab of researcher Shinya Yamanaka at Kyoto University, who through five years of tinkering finally brought the embyronic-like stem cells to life in tiny, microscopic clusters.[4] When a muscle stem cell starts to change and develop into a muscle cell, one result is the creation of long muscle fibers.  This occurs, for example, when a muscle grows in a young organism or when it tries to repair itself after an injury.[1] Muscle tissues are the body’s most abundant body tissue.

Skeletal muscles are held to the bones with the help of tendons (say: ten -dunz). Tendons are cords made of a very tough tissue, and they work as special connectors between bone and muscle, and are organized into hundreds of motor units , each of which involves a motor neuron, attached by a series of thin finger-like structures called axon terminals . These attach and control bundles of muscle fibers. Humans have three main types of muscle fibers, each containing a different variety of a protein called myosin heavy chain (“MHC”), which the researchers explained is the “microscopic motor” that makes your muscles move. The three types include MHC I (slow twitch fibers), IIa (fast twitch) and IIx (super-fast twitch).[5] Skeletal muscles are controlled by the somatic nervous system (SNS).

[1] – Science Daily, “Oscillation in muscle tissue”, https://www.sciencedaily.com/releases/2019/03/190315125246.htm

[2] – ALS News Today, “Rescuing Impaired Skeletal Muscle Function May Help Relieve Some ALS Symptoms”, https://alsnewstoday.com/2019/03/05/rescuing-impaired-skeletal-muscle-function-may-help-relieve-some-als-symptoms/

[3] – Medical News Today, “What are stem cells, and what do they do?”, https://www.medicalnewstoday.com/articles/323343.php

[4] – New Atlas, “Revolutions: The incredible potential of induced pluripotent stem cells”, https://newatlas.com/induced-pluripotent-stem-cells/58965/

[5] – CTV News,”Women’s muscles as well-equipped as men’s for weightlifting, study finds”, https://www.ctvnews.ca/health/women-s-muscles-as-well-equipped-as-men-s-for-weightlifting-study-finds-1.4356157

[6] – the sports daily, “Best Nootropics for Athletic Performance”, https://thesportsdaily.com/2019/03/25/best-nootropics-for-athletic-performance/

[7] – Public Library Of Science, “Skeletal Muscle Fiber Type: Influence on Contractile and Metabolic Properties”, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC521732/?fbclid=IwAR3G9BhhW4TxevCRw55vtE3JTYTHQj1EiRgiN624RBVDh3-DpdxZPyGkzPg#!po=1.21951

Informative Video Of Extrafusal Muscle Fibers By The Audiopedia on YouTube