The Adrenal Glands
Each of the adrenal glands, one atop each kidney, has a cortex, or outer
portion, and medulla, or central section. The cortex secretes about 30 hormones
and regulates many metabolic processes. The medulla produces the hormone
epinephrine, more commonly called adrenaline. Adrenaline output is stepped up
when you become fearful, angry, or excited-leading to a speed-up of heartbeat
and many chemical changes that prepare the body for action.
Among the major
functions of the adrenal cortex and its hormones are the control of salt and
water content of the body, and the control of sugar and protein metabolism. The
cortex also secretes a hormone similar to that put out by the testes. In some
tumors of the cortex, women develop masculine characteristics such as a deep
voice and facial hair, and menstruation may slow or cease. In men with such
tumors, the masculine secondary sex characteristics become more pronounced.
Underfunctioning of
the adrenal cortex produces a rare disorder, Addison's disease, discussed
elsewhere. With cortisone and other preparations, Addison's disease can be
controlled and the afflicted person can lead a normal life.
Both cortisone, an adrenal hormone preparation, and various
derivatives of it, can replenish the body's supply when the adrenals function
improperly. In addition, these medications may bring about favorable results in
such diseases as arthritis, asthma, sarcoidosis, and rheumatic fever. The
reason is not yet clear, for people with such diseases do not appear to be
deficient in adrenal hormones and yet additions to the normal output sometimes
produce striking improvement.
The Pituitary Gland If you think of one line
drawn through the head from ear to ear and another drawn backward from between
the eyes, the pituitary lays at the spot-at the base of the brain-where the two
lines cross. It consists of an anterior or front lobe; an intermediate part;
and a posterior or back lobe. The secretions of the pituitary are many and
perhaps still more remain to be discovered. From the anterior lobe come
powerful agents that influence other endocrine glands as well as various body
regions. ACTH, adrenocorticotrophic hormone, stimulates the adrenal cortex.
Thyro-trophic, or thyroid-stimulating hormone, often called
TSH, regulates size and activity of the thyroid gland. Also from the anterior
pituitary comes a hormone called the growth hormone, which has an important
influence on height. During the years when a child
is moving toward adulthood, the anterior pituitary secretes gonadotrophic
hormone which stimulates the reproductive organs. After childbirth, the
anterior lobe secretes lacto- genic hormone which causes milk to flow. One of
the posterior pituitary hormones, vasopressin, helps regulate water balance in
the body.
Another, oxytocin, stimulates smooth muscles such as those of the
digestive organs and the uterus. Research is constantly revealing new facts
about the pituitary and the relationship among the various glands of the
endocrine system. Scientists are trying to unravel the mysteries of the thymus
and pineal glands. When such problems are solved, it can be expected that many
more dis- eases may become not only curable but preventable.
Pituitary gland
diseases are rare. Inadequate pituitary secretion causes some types of
dwarfism; excessive secretion stimulates growth to gigantic proportions.
Pituitary tumors may press on the optic nerves and produce some loss of vision
and headaches. Acromegaly, in which bones increase in size, particularly the
bones of face, hands and feet, is caused by an overactive pituitary. Cushing'sdisease also is sometimes caused this way. Underactivity of the anterior lobe
of this complex gland leads to a thin, malnourished condition, Simmonds'
disease.
Pituitary insufficiency can cause children to become excessively fat.
In some cases, a condition called Frohlich's syndrome develops; children who
have it are excessively obese and sexually underdeveloped. If given an extract
of pituitary gland in time, they become normal and are spared unhappy lives. If
pituitary secretion decreases after puberty, fat may accumulate around certain
portions of the body, particularly the hips. When the back lobe of the
pituitary fails to function properly, excessive urination results-as much as 30
quarts a day.
This rare malady is diabetes insipidus, not to be confused
with" ordinary" diabetes mellitus. While effective replacements for
all pituitary hormones are not avail- able, treatment of the organs affected by
specific hormones is often possible. Thus, cortisone, thyroid, and sex hormones
are often employed for patients suffering from specific pituitary hormone
problems.
For patients affected by dwarfism, human growth hormone has become
available; it is effective only in specific cases and only if administered
before the normal growth period has ended. The Sex Glands (Gonads) The gonads(derived from the Greek word meaning seed) consist of the testes in men, the
ovaries in women. In addition to producing sperm and ova, the glands elaborate
hormones that are responsible for the special male and female characteristics.
