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Preksha Dhyana :
Then the fibre relaxes until another impulse arrives.'
Smooth Muscles react much more slowly than skeletal muscles. The nerves when present, alter the activity of the muscle rather than initiating it.
Heart Muscle also has a built-in mechanism to maintain rhythmical contraction quite independently, impulses for contraction coming from within the muscle itself. The Mechanics of Contraction
Skeletal Muscle fibres contract in response to nervous stimuli and the weakest stimulus that can initiate contraction is known as threshold stimulus. When muscle fibres receive a stimulus strong enough to elicit a response, the fibres contract with the maximum force possible or they no not contract at all. But a skeletal muscle as a whole is made up of millions of individual fibres and, therefore. exhibits graded response rather than all-or-nothing one. Thus the same hand that can pick up an egg without cracking it can also wield a sledge hammer. The Chemistry of Contraction
The muscles convert chemical energy into mechanical work. Muscles need a good blood supply to bring glucose and oxygen and to remove waste products. The actual chemical process involves the oxidization of glucose, thereby releasing energy which is used by the muscles to contract. The process needs a liberal supply of oxygen. In the absence of oxygen, the muscles can convert the glucose to lactic and which still gives the necessary energy. Skin (Integument)
The skin is rightly described as the largest functional organ of the human body, since it covers an area of 1.5 to 2 square meters in an average adult person. It is the outer covering of the body and has a wide variety of functions in protecting the watery internal environment of the human body from the ravaging effects of the dry external environment. The skin protects the body from microbes, injury to delicate inner tissues, the injurious effects of chemicals and damage by ultraviolet radiation of the sun. It, thus, is 1. If this chemical mechanism is blocked, the result would be paralysis.
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