THYROID AND PITUITARY

The thyroid and the pituitary have often been compared.  The anterior gland and the thyroid arise from almost the same spot in the embryonic oesophagus, the thyroid being an outgrowth in front, the anterior pituitary an outgrowth behind of the same soil.  They both control growth marvelously, also the differentiation, the mass and intricacy of the tissues.  But they differ in the site of their control.  The thyroid bears more directly upon the inner and outer coverings of the body, the skin, the skin glands and the hair, the mucous membranes, and the irritability and the preparedness for response of the nerves.  The pituitary acts more upon the framework of the body, the skeleton and the mechanical supports and movers.  Bone and ligament, muscle and tendon seem to be within its immediate sway.  The secretion or secretions of the pituitary diffuse directly into the fluid bathing the nervous system, supplying beneficent stimulants and aiding in the abstraction of harmful waste.  So while the thyroid raises the energy level of the brain, and the whole nervous system, as a byproduct of its general awakening effect upon all the cells of the body, the pituitary probably stimulates the brain cells more directly, perhaps in the manner of caffeine or cocaine.

The difference between the thyroid and the pituitary might be put this way:  that while the thyroid increases energy evolution and so makes available a greater supply of crude energy, by speeding up cellular processes, the pituitary assists in energy transformation, in energy expenditure and conversion, especially of the brain, and of the sexual system.  In short, the thyroid facilitates energy production, the pituitary its consumption.  The pituitary appears therefore as the gland of continued effort.  Hence fatigability, an inability to maintain effort, is one of the prominent complaints when there is destruction or an insufficiency of it for one reason or another.  As such, it contrasts with the glands of emergency effort, known as the adrenals.

CHAPTER III

THE ADRENAL GLANDS, THE GONADS, AND THYMUS

Like the pituitary, each adrenal gland is a double gland, that is, consists of two distinct portions, united together, one might say, by the accident of birth.  It would be confusing, however, to speak of each as two glands, because there are, as a matter of fact, two separate adrenal glands, one in the right side of the abdomen, and the other in the left.  Each gland is composite, or duplex.  How the two parts came to be united is a long story, interesting but too long to be recounted here.  In fishes they are apart and independent.

Each adrenal is a cocked hat shaped affair, astride the kidneys, easily recognized because of its yellowish fatty color.  Indeed, for centuries the glands were not given a separate status as organs, but were passed up as part of the fat ensheathing the kidney.  In childhood and youth, in common with the other glands, they are relatively larger and more prominent than in the adult.  Also, at every age, the amount of blood passing through them is very large compared to their size.  Their tremendous importance in the body economy accounts for their being so favored.