Glynda Walker, age 13, of Albuquerque, N.M., for her question:
WHAT DO GLANDS DO?
Glands are cells or groups of cells inside our bodies that help to regulate the way the body functions. Every gland has a special purpose.
There are two types of glands. They produce liquidLike substances that are known either as secretions or excretions.
If the gland secretes, a substances is discharged into the body. This is what we call an endocrine gland. If the gland excretes, the fluid it produces is discarded from the body. This is known as an exocrine gland.
An example of the secreting, or ductless, gland is the thyroid. Examples of excreting, or duct, glands are the kidney and the liver.
Sometimes lymph nodes are called glands. Actually, they are not true glands because they neither secrete or excrete. When the lymph node enlarges because of infection it should be called a swollen lymph node rather than a swollen gland.
The secretions of some endocrine glands contain hormones that have to reach the cells quickly at distant parts of the body. These glands are located close to tiny blood vessels called capillaries, so the fluid is able to rush quickly to where it is needed.
Each hormone has a job of its own to do to help keep the body in good health, and the body is harmed by either too much or too little of any endocrine secretion. When all is going well, the balance is exactly right.
Exocrine glands have tubes or ducts through which the excretion flows to the spot where it is used or discharged. The saliva glands, that move saliva to the mouth, are of this type.
Some exocrine glands produce a slimy substance called mucous. This is used in the nose and in the respiratory system.
Among the important exocrine glands are the salivary glands; the tear, or lachrymal, glands; the stomach glands; the mammary or milk glands; the kidneys; and the liver.
The pituitary gland, an important endocrine gland, secretes many hormones that are used to control other endocrine glands. The pituitary, which is also called the hypophysis,, is about the size of a pea. It is located in the central part of the brain.
The anterior or front part of the pituitary makes hormones that control the adrenals, thyroid and gonads. It also makes a hormone that helps control the growth of the body. If there's too much secretion, a person may grow to be larger than normal. If not enough, he may remain smaller than normal. The posterior pituitary makes a hormone that controls the body water sad blood pressure.
The thyroid gland is in the neck, in front and on either side of the windpipe. It produces a hormone called thyroxine, which is needed for the normal physical and mental growth of infants and children.