blood volume and blood pressure control. The adrenals are flat
triangular structures. The size and weight is somewhat vari-
able. Each is about 5 cm long and weighs between 3 and 6 grams
and is slightly heavier in the male than in the female.
The inner portion of the adrenals is developed from the ecto-
derm, the outer layer of cells of the embryo. This is the same tis-
sue that produces the sympathetic nervous system. The inner
portion secretes adrenalin and noradrenalin. Adrenalin is involved
in the “fight or flight” response, whereas noradrenalin causes more
vasoconstriction resulting in marked elevation in blood pressure.
The amount of adrenaline and noradrenalin that circulates in
the blood is minute in quantity but its action is powerful and
farreaching.
Its release is triggered by impulses from the sympathetic ner-
vous system in times of mental or physical stress, the entry of
adrenalin into the blood causes a tremendous heightening of vigor.
The brain and the sympathetic nervous system become activated.
Concentration of blood glucose is raised by conversion from gly-
cogen, which is stored in the liver. More blood cells are poured into
circulation from the blood pools of the liver and spleen. The heart
beats more strongly and faster, the pupils of the eyes are dilated,
enabling the person to see more clearly, breathing is more rapid,
the body temperature rises and the basal metabolism is increased.
There is an opposing effect on the digestive system, however,
wherein there is a loss of appetite and reduced motility.
Adrenalin adds strength and alertness to both physical and
mental activity. It gives force in combat and swiftness in flight. As
the activity of adrenalin is regulated by the sympathetic nervous
system, the secretion of it can be increased by the stimulation of
these nerves alongside the spinal column.
Some doctors believe that there is a condition called “low
adrenals”. A person with a deficiency of adrenalin will appear weary
and sensitive to cold, have cold hands and feet, loss of appetite, a
tendency to worry, will weep easily and will sometimes even have
a nervous breakdown. In children, learning problems develop,
growth is slowed, and they cannot be driven or hurried. If we inject
someone with adrenalin, his heart will contract more violently and
beat faster, he will feel anxious, and will get frightened easily and, if
subjected to it for some time, will become a very nervous person.