The Importance of Muscle

Vertebrate muscle tissue is involved in almost every bodily function. In particular, any function requiring the movement of some body part or parts needs to have a source of motive power. For this purpose, evolution has resulted in the development of the specialized muscle tissues found in all vertebrates, which account for up to 50 percent of their total body weight.

Because of the muscle-tissue characteristics of excitability (the ability to respond to stimuli), extensibility (the ability to be stretched), contractility (the ability to shorten actively and thereby generate force for the production of work), and elasticity (the ability to return to original length following extension or contraction), vertebrates have a wide range of important capabilities available which assist them in their survival.

For the muscular system, disease states or disorders resulting from improper nutrition, injury, or toxic substances are very often life-threatening conditions. This is most obvious for disturbances of the respiratory muscles or of the muscles involved in eating and swallowing; however, mus cular disorders involving the heart, the circulatory system, the digestive tract, or any major group of skeletal muscles may also prove to be life-threatening.

The most common heart problems are caused by reduction or blockage of the blood supply to the heart muscle. Reduced blood supply usually is the cause of a reduced oxygen supply. The insufficient oxygen supply weakens the heart-muscle cells, causing the condition of ischemia. Complete interruption of the blood supply to an area of cardiac muscle tissue usually results in necrosis (death) of the affected muscle cells; the condition is referred to as myocardial infarction. The dead muscle cells do not regenerate but are replaced by scar tissue, which is not contractile. This results in decreased pumping efficiency by the heart. De pending on the size and location of the dead area, the result may range from barely noticeable to sudden death.

As a consequence of some bacterial infections, it is possible for the lining of the heart muscle to become inflamed. This can then result in abnormal irritation of some of the heart-muscle cells. These cells can then disrupt the normal auto-rhythmicity of the heart. Irregular heartbeats and/ or uncoordinated contractions among the heart-muscle cells ensues. These conditions are very serious and can lead to death.

See also: Amphibians; Anatomy; Bone and cartilage; Endoskeletons; Fish; Flight; Heart; Histology; Locomotion; Mammals; Muscles in invertebrates; Physiology; Reptiles; Vertebrates.

Your Heart and Nutrition

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