Experimental work supports the view that the cortex and the medulla
have separate functions. The =medulla= of the adrenals is part of the
chromaffin system, which includes tissue of the same character in the
ganglia of the sympathetic, the carotid gland, and the accessory gland
called Zuckerkand’s organ. This system is derived from the same cells
as the sympathetic nerves. The medulla receives a richer blood supply
than any tissue in the body. The secretion of the chromaffin tissue is
called adrenalin or epinephrin. The blood receives a continuous supply
of the secretion, which acts upon the small blood-vessels and assists
in maintaining blood pressure. It also stimulates glandular tissue,
and has some effect upon voluntary muscle which tends to counteract
fatigue.
The =cortex= of the adrenal glands is of epithelial origin, and is part
of the so-called interrenal system, which comprises very small masses
of tissue in the sympathetic ganglia. These are located in the hilus of
the kidney, broad ligament, inguinal canal, prostate, epididymis, and
along the spermatic veins (Baker). The cortex is the chief glandular
tissue of the interrenal system. The amount of tissue is not so great
after puberty as before. The blood supply of the cortex is not so rich
as that of the medulla. Abnormal activity is claimed to be the cause of
certain sexual derangements, particularly sexual precocity.
Schafer states that the adrenals are very richly supplied with nerves.
Each receives no less than thirty-three nervous filaments (Kolliker),
derived in part directly from the splanchnic, in part from the
suprarenal plexus, which is itself constituted by branches from the
celiac, phrenic, and renal plexuses.
We have noted that in lesions (experimental) of the splanchnics a
few cases presented acute pathological changes, congestion with some
degeneration of cells, in the adrenals.
Macleod states that of the many functions of the adrenals that which is
most directly associated with epinephrin is the production of glucose
from glycogen. “When the nervous system is stimulated in such a way
as to excite the glycogenolytic process, two effects both operating
in the same direction with regard to the glycogenic function are
developed: the one, a hypersecretion of epinephrin, which activates the
sympathetic nerve endings, the other, the transmission of the nerve
impulse to the liver cell.”