Читать книгу The Glands Regulating Personality - Louis Berman - Страница 32

Under the microscope, as in the test tube, the thyroid shows remarkable and unique features. Closed spherules lined by a single layer of cells enclosing a gelatinous material known as colloid, which stains deeply with acid dyes, comprise the units of its architecture. Essentially, it may be pictured as a series of jelly bubbles secreted by outlying cells.

A relatively high percentage of iodine is the unique distinctive fact in its chemistry. Discovered by Baumann in 1895, the presence of the element has focused the intelligence of chemists upon the gland, with the consequent demonstration of arsenic also in it. It was soon manifest that the secretion of the gland was dependent upon the iodine content for its activity. Active extracts of the thyroid like thyreoglobulin and iodothyrin were proven to contain iodine, and to become inactive when the iodine was removed. Efforts to isolate the iodine containing active principle in pure form were fruitless until the work of Kendall at the Mayo Foundation. He obtained it as a white, finely crystalline, odorless and tasteless substance, heat stable, and analyzable. The free form separates as a sheaf of fine needles. Kendall at first called it the a-iodine compound, then named it thyroxin.

There are other internal secretions of the thyroid, with a function of their own, that have no iodine. But they are secondary, and obscure. Thyroxin is accepted today as the purified internal secretion of the thyroid because all the effects of the whole gland may be elicited with it. Thyroxin produces results with doses amazingly minute compared with the quantity of whole gland necessary. Moreover, a dose of thyroxin appears to last an organism in need of it over a period of time; the other has to be administered continuously.

Studies with thyroxin carried on in recent years have rounded out the whole concept of the business of the thyroid in the body economy. One may sum it up by saying that the thyroid secretion is the great controller of the speed of living. The more thyroid one has, the faster one lives; the less one has, the more slowly one lives.

That is not to imply any direct proportion between the amount of thyroid secretion in an individual, and the length of life to which he is destined. The speed of living, in the chemical sense (which is the fundamental sense), and the rate at which the chemical reactions go on that constitute the process of life, are dependent upon the thyroid. When the reactions go faster, more oxygen and food material are burned up or oxidized, more energy is liberated, the metabolic wheel rotates more quickly, the individual senses, feels, thinks and acts more quickly.

Likening one energy machine to another, the thyroid may be compared to the accelerator of an automobile. That is a rough and superficial comparison because an accelerator lets in more of the fuel to be burned up, while the thyroid makes the fuel more combustible. It thus resembles more the primer, for a rich mixture of gasoline and air burns at a greater velocity than a poor one. But the action of thyroid could really be simulated only by some substance that could be introduced into the best possible of gasoline mixtures, to increase its combustibility by a hundred per cent or more. For that is what thyroid will do to our food. Nor has it only this destructive or combustion side. Withal there is at the same time a constructive action, for the process frees energy to be used for heat, motion or other need. The thyroid, therefore, in addition to its rôle as an accelerator, acts, too, as the efficient lubricator for energy transformations. So we see it as accelerator, lubricator and transformer of our energies.