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A classic example of a syncytium is the formation of skeletal muscle.Large skeletal muscle fibers form by the fusion of thousands of individual muscle cells. The multinucleated arrangement is important in pathologic states such as myopathy, where focal necrosis (death) of a portion of a skeletal muscle fiber does not result in necrosis of the adjacent sections of that same skeletal muscle ...
The sliding filament theory explains the mechanism of muscle contraction based on muscle proteins that slide past each other to generate movement. [1] According to the sliding filament theory, the myosin ( thick filaments ) of muscle fibers slide past the actin ( thin filaments ) during muscle contraction, while the two groups of filaments ...
During muscle contraction, the I band will shorten, while an A band will maintain its width. [2] The muscle is made up of several myofibrils packed into functional units surrounded by different layers of connective tissues (epimysium, perimysium, and endomysium). The main contractile unit is mainly composed of protein filaments (myofilaments ...
The termination of muscle contraction is followed by muscle relaxation, which is a return of the muscle fibers to their low tension-generating state. [ 1 ] For the contractions to happen, the muscle cells must rely on the change in action of two types of filaments : thin and thick filaments.
There are three types of myofilaments: thin, thick, and elastic that work together to produce a muscle contraction. [14] The thin myofilaments are filaments of mostly actin and the thick filaments are of mostly myosin and they slide over each other to shorten the fiber length in a muscle contraction.
An impulse from a nerve cell causes calcium release and brings about a single, short muscle contraction called a muscle twitch. If there is a problem at the neuromuscular junction, a very prolonged contraction may occur, such as the muscle contractions that result from tetanus. Also, a loss of function at the junction can produce paralysis. [5]
The myofilaments act together in muscle contraction, and in order of size are a thick one of mostly myosin, a thin one of mostly actin, and a very thin one of mostly titin. [1] [2] Types of muscle tissue are striated skeletal muscle and cardiac muscle, obliquely striated muscle (found in some invertebrates), and non-striated smooth muscle. [3]
The skeletal system serves as a framework for tissues and organs to attach themselves to. This system acts as a protective structure for vital organs. Major examples of this are the brain being protected by the skull and the lungs being protected by the rib cage. Located in long bones are two distinctions of bone marrow (yellow and red).