THE PULSE.--At the wrist (_k_, radial artery) and on the temple
(temporal artery) we can feel the expansion of the artery by each little
wave of blood set in motion by the contraction of the heart. In health,
there are about seventy-two [Footnote: This number varies much with age,
sex, and individuals. Napoleon's pulse is said to have been only forty,
while it is not infrequent to find a healthy pulse at one hundred or over.
In general, the pulse is quicker in children and in old people than in the
middle-aged; in short persons than in tall; in women than in men. Shame
makes the heart send more blood to the blushing cheek, and fear almost
stops it. The will can not check the heart. There is said, however, to
have been a notable exception to this in the case of one Colonel Townsend,
of Dublin, who, after having succeeded several times in stopping the
pulsation, at last lost his life in the act.] pulsations per minute. They
increase with excitement or inflammation, weaken with loss of vigor, and
are modified by nearly every disease. The physician, therefore, finds the
pulse a good index of the state of the system and the character of the
disorder. (See p. 314.)
THE VEINS are the tube-like canals which convey the blood _to_ the
heart. [Footnote: There is one exception to the general course of the
veins. The _portal_ vein carries the blood from the digestive organs
to the liver, where it is acted upon, thence poured into the ascending
vena cava, and goes back to the heart.] They carry the dark or venous
blood (note, p. 119). As they do not receive the direct impulse of the
heart, their walls are made much thinner and less elastic than those of
the arteries. At first small, they increase in size and diminish in number
as they gradually pour into one another, like tiny rills collecting to
form two rivers, the vena cava ascending and the vena cava descending
(_l, m_, Fig. 34), which empty into the right auricle.
Some of the veins creep along under the skin, where they can be seen, as
in the back of the hand; while others accompany the arteries, some of
which have two or more of these companions.
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