Blood Functions
Broadly conceived, the function of the blood is to
maintain the constancy of the internal environment (homeostasis).
The circulating blood makes possible human adaptability
to changing conditions of life—the endurance of wide
variations of climate and atmospheric pressure; the
capacity to alter the amount of physical activity; the
tolerance of changing diet and fluid intake; the resistance
to physical injury, chemical poisons, and infectious
agents. The blood has an exceedingly complex structure,
and many components participate in its functional activities.
Some of the regulatory mechanisms with which the blood
is involved include sensors that detect alterations
in temperature, in pH, in oxygen tension, and in concentrations
of the constituents of the blood. Effects of these stimuli
are in some instances mediated via the nervous system
or by the release of hormones (chemical mediators).
Some of the major functions of the blood are outlined
in the paragraphs that follow.
