(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
body.
Section IV. THE PARATHYROID GLANDS
10-9.
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.
10-10. HORMONE
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.
10-12. HORMONES
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
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