Blood Functions. pH
The pH of blood is kept relatively constant at the
slightly alkaline level of about 7.4 (a pH of less than
7 indicates acidity, of more than 7 alkalinity). Venous
blood is maintained at a somewhat less alkaline level
(7.35) because of the higher carbon dioxide content.
A system ofefficient buffers in the blood and the selective
excretory functions of the lungs and kidneys keep the
pH within these narrow limits. Physiological mechanisms
stabilize a normal pH in the blood both by regulating
the rate and depth of respiration in order to maintain
a normal tension of carbon dioxide in the blood and
by excreting acid or alkaline urine from the kidneys.
