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The muscle cell
A muscle cell is a special kind of cell that makes up an organism's muscle tissues. The muscles allow independent movement and regulate biological functions such as digestion andheartbeat. These cells are further specialized into distinct types based on their location and functions. All of them control movement by contracting; while much of this activity is involuntary, themuscles that direct the skeletal system can be consciously controlled. These muscles can be trained to carry out highly precise movements and strengthened through exercise.
Cellular Biology
Allorganisms are composed of structures called cells, many of which are microscopic. In complex creatures such as humans, these cells number in the trillions, and become highly specialized in early development.Nerve cells, for example, make up the brain and nervous system and can reach lengths of 3 feet (1 m), but are incapable of independent movement. Muscle cells, by contrast, have structures that allowfor a wide range of motion, from the measured routines of a gymnast to the constant beating of the heart.
Types of Muscle Tissue
The medical term for a muscle cell is a myocete. During theembryonic, or pre-birth, stage of development, cellular bodies called myoblasts mature and develop into the various kinds of myocetes. In humans and higher animals, there are three kinds of muscle cells,corresponding to the major categories of muscle: skeletal, cardiac, and smooth.
Muscle cells are made up of myofibrils, organic cable-like structures composed of essential proteins. Within themyofibrils are bundles of these proteins, arranged into thick and thin filaments within repeating sections known as sarcomeres. Responding to voluntary or involuntary nerve commands, these proteins slide pasteach other, causing the muscle cells to contract or relax and create movement. These mechanisms for motion are called actomyosin motors, referring to the proteins that compose them, actin and...