PULSE (from Latin, pulsus, a beating), the rhythmical motion of an artery, with al ternate expansion and contraction, in practice considered as a beating. This motion is strong est in the heart (q.v.), which is the centre of the arterial system; and from that organ it is prop agated through all the minutest branches of the arteries. In those which lie immediately under the skin it can be felt with the finger, as is the case with the radial artery, the pulsation of which is very perceptible at the wrist. The state of the pulse is therefore an indication of the action of the heart and the whole arterial sys tem and of the condition of the blood and the physical functions in general. The circum stances to be attended to in the pulse are either the number of pulsations which take place in a given time and the regularity or irregularity of their occurrence, or the character of each pul sation. In the former case the pulse is said to be quick or slow according to the number of pulsations in a given interval; regular or ir regular, as they occur at equal or unequal in tervals. In the latter case it is strong or weak, hard or soft, full or small. It is affected by the age, sex and temperament of the individual, and by accidental circumstances, as sleep, food, ex ercise, heat.
The pulse is most rapid in infancy, making from 110 to 140 beats per minute. During early childhood it makes from 100 to 110 and is regu lar and rather soft and small. In youth it is much slower, making from 80 to 90 beats per minute. At this period it is regular, strong, rather soft than hard, moderately full. In ma ture age the number of beats is on the average about 75 per minute and the pulse is regular, strong, or moderate, fluctuating between hard and soft, between full and small. In old age
the number of beats sinks to about 60. In the female the pulse is more rapid, softer and smaller than in the male. In persons of a sanguine temperament it is quicker and fuller than in phlegmatic individuals. Sudden agita tion and violent passions make the pulse rapid and irregular; joy makes it quick and strong; long-continued grief, languid and soft. The pulse is, therefore, a highly important indication of the state of the system. A deviation from the regular pulse of an idividual indicates a dis ordered state. When the irritability of the sys tem is so heightened as to produce fever or in flammation the pulse is accelerated. If the action of the nervous system is irregular, or un duly heightened, the pulse becomes frequent and irregular. In case of mechanical obstructions to the circulation, as in dropsy of the pericardium, polypus in the heart or in the great arteries, the pulse is irregular and interrupted.
The study of the pulse began with the an cients. Galen wrote several works on it and for several centuries the subject of pulsation re mained much as he left it. The demonstrations of the circulation of the blood by Harvey and of the irritability of the muscular fibre by Haller threw new light on it, and medical sci ence at last has brought it under full investi gation and has explained it in all its physiologi cal aspects. See ARTERIES, DISEASES OF THE; HEART.