a. Description. The gonads are the sex glands. In the female, the gonads are
the ovaries which are located in the pelvic cavity. In the male, the gonads are the testes
which are located in the scrotum. These glands give the primary sex characteristics in
the growth and development of the primary reproductive organs at puberty. These
glands are also responsible for the secondary sex characteristics.
(1) Hormones in females. The ovaries, in the female, produce estrogen,
progesterone, and relaxin. Estrogen is responsible for stimulating the development of
the female sex organs and secondary sexual characteristics of voice pitch, broad pelvis,
and hair pattern. Progesterone acts with estrogen to regulate menstruation. Relaxin
causes the birth canal to widen.
(2) Hormones in males. The testes, in the male, produce the hormone
testosterone. Testosterone is the principal male hormone and has a number of effects
on the body. First, this hormone controls the development, growth, and maintenance of
the male sex organs. Additionally, the hormone stimulates bone growth, sexual
behavior, final maturation of sperm, and development of male secondary sex
characteristics. Secondary male sex characteristics include the following:
(a) Muscular and skeletal development such as wide shoulders and
(b) Body hair patterns that include pubic hair, armpit hair and chest
hair, facial hair, and hair recession at the temple.
(c) Enlargement of the thyroid cartilage of the larynx which produces
the deepening of the male voice.
Testosterone is also responsible for stimulating the descent of the testes just
before a male is born.
The interworking of the endocrine system with all other systems is a remarkable
and delicate balance. As you evaluate your patients, you will not be looking for
diseases of the adrenal medulla or thyroid gland but the symptoms of what their
malfunction will show. Keep in mind that your patient's body is a complex machine
where every part affects another part.