PHYSIOLOGICAL ANALYSIS OF POSTURE: FUNCTIONS OF SPINAL MUSCLES - REFLEXES

First I must explain what reflexes are. A reflex is a reaction of the body to certain changes that take place within the body. Let us see how in the following examples:1You touch something hot and automatically the hand is snatched away to prevent the fingers from getting burned. The nerve endings on the fingertips that feel heat send impulses via sensory nerves to the spine where a ‘process centre’ or ‘analysing centre’ in the brain promptly sends commands to the muscles via motor nerves to withdraw the hand immediately. This path from fingertips to the spine to the muscles of the arm is a reflex. It is almost like the rays of the sun being reflected by a mirror on to the wall.2You feel cold and the body responds to it in a certain way: you shiver to generate more body heat; you get goose pimples to trap a layer of air between ‘raised hair’ on the skin to prevent heat loss from its surface; your body mobilises reserve glucose and fat to release more fuel to generate heat. All these different responses (involuntary) come about because of the stimulation of cold ‘receptors’ or nerve endings on the skin. These receptors send messages to the subconscious brain which processes the information before sending commands to the autonomous (involuntary) nerve centres to shiver, create ‘goose bumps’ and release glucose. This is a complex reflex with a series of reactions to a single stimulus (cold).*79\330\8*

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