While most people have four small parathyroid glands poised around the thyroid gland, about 14% of the population have one or two additional parathyroid glands. Because these oval glands are so small, the extra space occupied by extra glands does not seem to be a problem. The sole function of these glands is to regulate calcium levels in the body. Although this may seem like a simple task, the maintenance of specific calcium levels is critical. Calcium has numerous important bodily functions. Calcium makes up 2-3% of adult weight with roughly 99% of the calcium in bones. Calcium also plays a pivotal role in muscle contraction and neurotransmitter secretion.
Science EncyclopediaScience & Philosophy: Electrophoresis (cataphoresis) to EphemeralEndocrine System - History Of Endocrinology, Basic Endocrine Principles, The Pituitary, The Pineal, The Thyroid, The Parathyroids