The Endocrine System - Part 2

The pancreas. Another of the essential organs is the pancreas. Within it are the islets of Langerhans, groups of cells that secrete insulin, a hormone essential to the conversion of sugar to energy. The pancreas also controls the way fats are stored in the body.

The disease that results from a deficiency of insulin is called diabetes. This disease was fatal until Dr. Frederick Banting and four other Canadian  doctors  discovered  that secretion of the islets in the pancreas would stop the symptoms of diabetes They found that insulin controlled the way the body uses sugar. By injectiing insulin into patients, the disease could be arrested.

The thyroid gland. The thyroid is another part of the endocrine system The thyroid is a gland which straddles the trachea. The hormone thyroxin produced in this small gland, influences the body’s ability to use foods; consequently, it controls body weight, growth, development of intelligence, and certain other processes.

One of the important factors in the functioning of the thyroid is iodine. If sufficient iodine is not present in the diet, the thyroid enlarges and forms an ugly swelling in the neck, called a goiter. A goiter condition can be prevented by eating sufficient iodine in the form of seafood, iodized salt, or certain plants. People living in regions where iodine is especially common in foods do not need iodized salt.

The parathyroids. Buried in the thyroid gland are four parathyroid glands. These glands are tiny spots on the thyroid gland and are vital life. They secrete a hormone that controls the level of calcium in the blood This calcium controls muscle bility. A muscle deprived of calcium will twitch uncontrollably. Too much parathyroid hormone, on the other hand, will cause the bones to give up calcium to the blood, a condition equally undesirable.

The other endocrines. There are other endocrine glands of varying degrees of importance. These glands also work through the blood stream and control various body functions.

Balance in the body. The chemical controls in the body are just part of the interlocking systems that normally function so well together. Doctors long ago devised the concept of homeostasis, or automatic balance, to explain this balance. The body is such a complex series of dependent parts that damage
to one part will affect dozens of others. The body’s homeostasis automatically corrects for many of these imbalances, and brings the body parts into harmony again. In sickness, homeostasis may cure you without help from a doctor. It adjusts your functions to compensate for diet, temperature change and all manner of other upsetting factors in your environment. Without such a capacity for maintaining balance, you would not have a chance to lead a healthy, comfortable life.

The Endocrine System - Part 1

The control centers. The endocrine glands secrete chemicals which control the growth and development of the body. These chemicals are secreted into the blood stream and are carried to all parts of the body. Because they are in general circulation, these chemicals, called hormones, can act in areas far from the gland that secreted them. They may even act on several organs at once.

The endocrine glands have a certain similarity to the nervous system because they help to integrate the activities of widely separated organs. Emotional strain, for example, causes one of the endocrines to enlarge and secrete a chemical which speeds up the action of the heart.

The master gland. In the base of the skull is a tiny gland called the pituitary, or hypophysis. This gland is called the master gland because it controls growth and the action of the adrenal, thyroid, and male and female glands. Through these glands, it has an enormous effect on the other systems of the body.

The pituitary gland secretes at least eight hormones in order to exercise its control over body functions. Each hormone controls a particular body function. Examine the chart below to see what functions these eight hormones control.

The adrenals. The adrenal glands are two of the glands that are regulated by the pituitary. The adrenals are two glands located above the kidneys. Each adrenal is composed of two parts: an inner part, called the medulla, and an outer layer, called the cortex.

The hormone secreted by the medulla, called epinephrine, is probably the best known hormone in the body. Commonly called adrenalin, this hormone stimulates most of the emergency reactions within the body. It increases the heart beat, releases sugar from the liver into the blood stream, delays fatigue in the skeletal muscles, raises the blood pressure, and performs many other functions.

In view of these effects you would think that epinephrine is essential to the function of the body. Such is not the case, however. Parts of the autonomic nervous system can control these functions even when the adrenal medulla is removed from the body! It is likely that the medulla serves only to help the autonomic nervous system in times of danger, but that it is not necessary for the body’s functioning.

The adrenal cortex. The adrenal cortex, on the other hand, secretes substances which’ are vital to the body. A person deprived of his adrenal cortex would die within a few days. It is the secretion of the hormone from the adrenal cortex that is controlled by ACTH, a hormone secreted by the pituitary. Scientists are not sure why the cortex is essential, although they have found that cortisone is very useful in alleviating some symptoms of disease.