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Preksha Dhyana
ends in the skeleton and produce movement by contracting and relaxing in response to conscious efforts of the will. They are also called striped muscles, because their long, thin fibres have fine, dark and light cross markings called the H band and the I band. Muscle fibre is built up from fibrils aligned together.
The basis of the bodily movement is the ability of the muscular tissues to contract and relax in response to nervous messages. An innumerable variety of movements can be produced because of the complexity of the muscle arrangement in the body. In fact, almost every muscle has an antagonist which produces the opposite action. This enables one to control every movement in force and range, while the intricate arrangement of the muscles across joints allow the greatest possible diversity of action. The biceps and triceps provide an instance of muscular antagonism. While the biecps is contracted, the triceps is relaxed and vice versa.
The muscles of the intestines and certain other structures like blood vessels and the uterus are called smooth muscles, because unlike the limb muscles they have no cross markings. They contract involuntarily or automatically and are relatively slow in action. Normally the smooth muscles do their work silently and we are unaware of their action.
The heart or cardiac muscle is a unique type found nowhere else in the body. It is intermediate between striated and smooth muscles. It is unique because its contractions are inititated within the muscle itself.
Energy is required to contract the muscle. It comes from glucose which is derived from glycogen stored in the muscles. Lactic acid which is formed during muscular 'action accumulates in muscles which are used for any length of time and excess amount of it causes cramp.
'Muscle tone or tonus' is the residual degree of contraction in muscles imparting firmness and resistance to stretching. It is important in keeping the muscles in a state of readiness to respond to stimuli. (v) Nerve Tissue
The cells of never tissue are specialized in two key
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