ADRENALS, also known as suprarenal glands. Paired structures, which in the human animal are located in the kidney fat just above the kidney. They have no physiological rela tion with that organ. They are a vital neces sity to life and removal of the glands by acci dent, experiment or disease causes almost in stant death. Disorders of the glands are numerous and of enormous importance to the well being of the body since by their internal secretion, the hormone, known as adrenalin, the blood pressure of the body is regulated. They belong to a group of structures, known as the glands of internal secretion, which are a part of the vegetative nervous system of the body, and the action of the hormone is chiefly made effective through the sympathetic fibres of this vegetative nervous system.
The suprarenal glands are made up largely of chromaffine tissue, which like the cells of the sympathetic ganglia is derived from neuroblasts of the central nervous system. The cortex of the suprarenals is made up of entirely different types of cells. Chromaffine cells are found also in the sympathetic para ganglia of the solar plexus, Zuckerkandl's aortic ganglia, the cardiac paraganglia, the coccygeal and cartoid ganglia of Luschka, and the tympanic naraganglia. The tissues them selves are richly supplied with sympathetic nerve fibres.
The chromaffine tissues produce a true in ternal secretion adrenalin, whose chemical composition is known: ortho-dioxy-phenyl ethanol-methylamine.
Its nearest relative is tyrosin, a well-known product of protein decomposition. The chief action of adrenalin is through the sympathetic nervous fibres increasing their reactive capacity, or sensitizing them as it were. The routine function of the chromaffine tissue is to react to metabolic stimuli largely in response to desire and fear. Their emergency function, as Cannon has termed it, is to provide the necessary over-response to emotional hyperac tivity, i. e., to increased or diminished desire and fear which, as their correlates love and hate, are the ultimate expressions in the sym bolic sphere of what are instinctively known as useful or harmful agencies to the organism and to the race. This over- or under-response brings about, through widespread vegetative nervous system activities, including those upon other endocrinous glands, the approximately necessary metabolic adjustment. This takes
place chiefly through the regulation of the blood volume and of the organic and inorganic constituents of its plasma. Adrenalin itself is present in the plasma in proportions of 1 to 20,000,000. Notwithstanding this extreme dilu tion it acts upon unstriped muscle fibre and on sympathetic receptors. Adrenalin then is a typical product which demonstrates the meta bolic regulation mechanisms of the vegetative nervous system. In addition to this broad function of keeping the sympathetic nerve fibres in adjustment it has certain specific func tions, over- or under-activity of which give rise to a typical hyperadrenalemia and to hypoadrenalemias. The latter syndrome, when well developed, is known as Addison's disease.
Furthermore, very minute amounts produce results antagonistic to those from large doses. This bears upon the facts known concerning the antagonisms of sympathetic and autonomic impulses. This idea should prove of service in t1,e entire range of opotherapy in calling atten tion to the results obtained by large and by small doses.
The most acute form which is present in complete or great loss to the suprarenals is rare. Pende, in