(called goiters) where there is little or no iodine available. A second hormone, calcito-
nin, is produced by the thyroid gland and it is involved with calcium metabolism in the
Section IV. THE PARATHYROID GLANDS
LOCATION AND STRUCTURE
Located on the posterior aspects of the thyroid lobes are two pairs of small
round masses of tissue, known as the parathyroid glands.
The hormone produced by these glands is called parathyroid hormone, or
parathormone. It is involved with calcium metabolism.
Section V. THE PANCREATIC ISLETS (ISLANDS OF LANGERHANS)
10-11. LOCATION AND STRUCTURE
Within the substance of the pancreas are distributed small groups of cells known
as islets. Although the pancreas is a ducted gland of the digestive system, these
isolated islets are, in fact, ductless glands.
Insulin and glucagon are the two most commonly recognized hormones of the
islets. These hormones are involved with glucose metabolism.
Section VI. THE SUPRARENAL (ADRENAL) GLANDS
10-13. LOCATION AND STRUCTURE
Embedded in the fat above each kidney is a suprarenal gland. Both suprarenal
glands have an internal medulla and an external cortex.
10-14. HORMONES OF THE SUPRARENAL MEDULLA
The medullary portion of each suprarenal gland produces a pair of
hormones--epinephrine (adrenalin) and norepinephrine (noradrenalin). These