Since the turn of the century, we have heard a great deal about a newly discovered system in the body-the endocrine system. This consists of many glands, including the thyroid gland, pituitary gland, gonads, pancreas, and adrenal glands. The diseases associated with the endocrine system range from the common problems of diabetes mellitus and irregular menstrual periods to Addison's disease-a problem with the adrenal glands that gained much attention when President John F. Kennedy was said to suffer from it. And most of us have at least one friend with an under-active thyroid gland.
The endocrine system consists of glands that empty their chemical products, called hormones, directly into the bloodstream. These hormones control nearly every aspect of our body's functioning, including metabolism (thyroid glands), sugar usage (pancreas), and sexual functioning (gonads). The release of epinephrine, which we would feel, for example, a few moments after an almost fatal accident, is the result of a release of a minute quantity of the chemical from the adrenal glands.
When a nerve cell is stimulated, it conducts the discharge all the way from one end to the other. As it reaches the end of the nerve, this information must cross a small space, called a synapse, to another nerve, muscle, or other kind of cell. It does this by releasing an extremely small quantity of a certain chemical, such as acetylcholine or a form of adrenalin (depending upon the kind of nerve cell). It is this tiny amount of chemical that causes the next cell to realize that a message has come down the nerve fiber. In a way, each nerve is like a tiny gland!
The endocrine glands are richly supplied with nerves and are rigorously controlled by the nervous system; I often view them as huge nerve endings. Instead of releasing minute amounts of chemical, as the tiny nerve endings do, the endocrine glands may release much larger quantities. They are, therefore, able to adjust the person's overall activity in many ways.
Just as you are able to increase the activity of your hand by moving it back and forth and up and down, it is possible for the thyroid gland to increase the overall activity and metabolism of your entire body. If you have an overactive thyroid gland or if someone gives you thyroid hormone pills, you may find your arms and legs moving much more often, feel nervous and jittery, and always feel too warm even though other people feel comfortable. On the other hand, too little thyroid hormone can cause feelings of being slowed down or drowsy and make a person tend to gain weight. In a similar fashion, the other endocrine glands may be seen as superenlarged nerve endings that regulate a person's overall activity in one way or another.
Because of their close association with the nervous system, there is much opportunity for the function of these glands to become involved in conditioned reflexes. In other words, a person's glands may secrete too much or too little hormone, depending upon what kind of stimuli are in the person's environment and what kind of thought patterns the person has. I have worked with several people who had improper secretion levels of the endocrine glands. In the course of exploration we saw a pattern of conditioning that was similar to that discussed up until now except that a change in the secretion of the gland became one of the responses. Following exploration and deconditioning there was an improvement in glandular function.