The autonomic system consists of two parts: the sympathetic and the parasympathetic parts, which exercise involuntary control of smooth muscle, cardiac muscle, and glands. The sympathetic system has similar effects on the body as those produced by the hormones adrenaline and noradrenaline: they bring about physiological changes that help the body to cope quickly under conditions of stress, the fight and flight reaction. Stimulation of the sympathetic system tends to speed up processes while stimulation of the parasympathetic system tends to slow things down. The systems work together to maintain a stable internal environment.
Stimulation of the sympathetic system causes the following changes: ^ the heart rate and strength of contraction increases ^ the coronary arteries dilate, increasing the blood supply to the heart ^ contraction of the spleen increases the volume of circulating blood
^ the blood supply to the organs of digestion decreases thus providing more blood for skeletal muscle contraction
^ the rate of respiration, oxygen consumption and carbon dioxide output increases ^ increase in the rate of conversion of glycogen, making more glucose available for energy ^ increase in the quantity of sweat secreted, with increased heat loss ^ the pupils dilate giving a wide-eyed look
Stimulation of the parasympathetic system balances the effect of the sympathetic system, producing opposite effects:
^ slows the heart rate and decreases the strength of contraction ^ constricts coronary arteries, decreasing the blood supply to the heart ^ reduces the rate of respiration and oxygen consumption ^ increases blood supply to the digestive system and stimulates peristalsis ^ constricts the pupils.
During massage the sensory receptors in the skin convey impulses of touch and pressure to the central nervous system. If pressure is too light it can be irritating; if it is too deep or uneven it may be irritating or painful. Muscles then respond with increased tension. Slow, rhythmical, deep massage has a soothing effect on the nerve endings, promoting relaxation.
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