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The Striated Muscle

Table of Contents
The Lungs
The Trachea
The Testes
The Submaxillary Gland
The Liver
The Stomach and Duodenum
The Blood
The Arteries and Veins
The Adipose Tissue
The Skin
The Pituitary Gland
The Pancreas
The Thyroid
The Kidney
The Spinal Cord
The Cerebellum
The Elastic Cartilage
The Bone
The Smooth Muscle
The Striated Muscle


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The muscles are fibrous, dense tissues, whose primary function is to allow the body to move by repeated contraction and relaxation. Besides movement, the muscle is also responsible for maintaining posture, stabilizing the joints, and producing body heat through muscle function.


The striated muscle is also known as the skeletal muscle, because it is attached mainly to the bones and skin, and is responsible for the mobility of the body and limbs.


The movement of striated muscle is controlled voluntarily, unlike the smooth muscle of the internal organs and the cardiac muscle of the heart, which are involuntary.


The skeletal muscles are composed of muscle fibers, long fused cells containing multiple nuclei. The muscle fibers are packed together in bundles by connective tissue and are packed with myofibrils.


Myofibrils are cylindrical arrangements of myofilaments, made up of proteins called actin and myosin, and which cause the light and dark banded appearance of muscle fiber. These myosin and actin filaments slide across each other, causing the muscle to contract.


The sliding of the myofilaments is caused by neural impulses. The axon terminuses of motor neurons located directly above the muscle fibers create a neuromuscular junction, in which synapses are formed between the muscle and the nerve.


When a nerve impulse travels down the axon, it causes the release of the neurotransmitter acetylcholine into the synapse. Acetylcholine diffuses across the synapse and attaches to the membrane of the muscle fiber, the sarcolemma.


The neurotransmitter causes sodium ion gates in the sarcolemma to open, and the rushing in of sodium ions causes an action potential across the membrane of the muscle cell, causing the entire muscle fiber to contract. The contraction of skeletal muscles pulls on the bones they are attached to, causing the entire appendage to move.

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