Figure 1-3. The thyroid gland and the parathyroid glands.
a. Description. The parathyroid glands are tiny bean-shaped glands embedded
on either side of the thyroid gland. There are usually four parathyroid glands, but there
may be more. The upper parathyroids are usually located at the point where the upper
and middle third of the thyroid gland meet. The lower parathyroids are usually located
in the branches of the inferior thyroid artery, but these parathyroids may be located in
b. Hormones. The parathyroid glands secrete the hormone parathormone.
This hormone regulates the concentration of calcium and phosphorus in the blood.
Parathormone also influences the passage of calcium and phosphorus among the
bloodstream, bones, and urine.
a. Description. The adrenal glands are located above the kidneys. The
adrenal cortex is the outer part of the gland, and the medulla is the inner portion of the