Forensic Pathology for Police - Brainshare Public Online Library

118 6 Overview of Anatomy and Physiology
Fig. 6.28 Gross appearance of the thyroid gland
hormone effects many other tissues and organs and is responsible for maintaining
normal metabolism. If someone has too much thyroid hormone, they have a hyperfunctioning
metabolism but if they have too little thyroid hormone, they have a
depressed metabolism. The other type of parenchymal cell within the thyroid gland
are the parafollicular C cells and these are scattered amongst the thyroid follicles.
The parafollicular C cells produce calcitonin, a hormone that plays an important role
in the metabolism of calcium and phosphorus. As such, its actions occur primarily
within the bone and kidneys.
Parathyroid Gland – There are usually at least four parathyroid glands, but
sometimes more. They are small, pea-sized glands that reside adjacent to the
thyroid gland within the anterior neck and produce parathyroid hormone, which
also plays an important role in calcium and phosphorus metabolism. Some of the
hormone’s effects are via the hormone’s ability to activate vitamin D within the
kidneys.
Adrenal Glands – The adrenal glands are small, triangular-shaped glands that
are present above the kidneys and have a distinct outer golden yellow cortex, as
well as an inner, brown-gray medulla (Fig. 6.29). The cortex is composed of three
zones of cortical cells (Disc Image 6.30): from outside to inside known as the zona
glomerulosa, the zona fasciculata, and the zona reticularis, which produce mineralcorticoids
(especially aldosterone), glucocorticoids (especially cortisol), and sex
steroids (estrogens and androgens), respectively. Aldosterone is important in sodium
and potassium metabolism. Cortisol can be thought of as the body’s major steroid −
it has many important physiologic roles, including immune function, glucose regulation,
blood vessel tone, and bone metabolism. The adrenal medulla is the source
of epinephrine (adrenaline) and norepinephrine and is also considered a part of the
sympathetic autonomic nervous system.