Other Endocrine Glands and Functions

The parathyroid glands, each about the size of a pea, are located at the four corners of the thyroid gland. They secrete Para hormone, which helps regulate the body's use of calcium and phosphorus. Too little of this hormone reduces the calcium level in the blood. Too much Para hormone, on the other hand, may prompt excessive calcium deposits in other than bone tissue, which is what is happening to the circus freak said to be "turning in­to stone."

The islet cells of the pancreas are only one part   of this   much   larger   internal   organ, which also manufactures digestive juices released through ducts. The hormone elabo­rated by the islet cells is insulin. It is essen­tial to the carbohydrate metabolism of the body. Without adequate insulin supply, the body cannot properly utilize starches and sugars. The failure of the islet cells to produce enough insulin is the direct cause of the dis­ease diabetes mellitus.

The thymus gland, situated on the wind­pipe, is classified as an endocrine, but it has no acceptably proved function. Large at birth, it generally withers and shrinks until at pu­berty it has practically disappeared.

One more observation about the endocrine system as a whole is pertinent. Since it in­fluences so much the course of physical growth and development as. for example, the advent of sex characteristics  it can also be said to underlie the psychological develop­ment of the individual, which waits on bio­logical readiness.

SLEEP

"God bless the man who first invented sleep," said Sancho Panza. voicing a senti­ment that echoes down the ages. Sleep, like mental health, is a phenomenon that invokes both mind and body. Furthermore it is indic­ative of a reasonable state of mental health, for sleeplessness is frequently a symptom of anxiety or other psychosomatic maladjust­ments that do not bespeak a good level of mental health. We have therefore chosen to deal with the subject of sleep in this place.

A human being spends approximately a third of his life in sleep. Yet for an activity or perhaps lack of activity so common and universal, we still know surprisingly little about its fundamental mechanisms. The most scientific explanations of the function of sleep hardly surpass Shakespeare's seventeenth-century description:

Sleep that knits up the raveled. of care, The death  of each   day's   life, sore labor 's

bath, Balm  of hurt  minds, great nature's second (nurse, ('hie) nounsher in life's feast.

There are many theories about sleep, but none is universally accepted. On the other hand many extended and acute scientific ob­servations have been made to illuminate the nature of sleep and the effects of lack of it. The longest that a man has been known to go without sleep and survive is a little over 9 days.