THE ENDOCRINE SYSTEM
This system consists of the ductless glands that release hormones. It works together with the nervous system in regulating metabolic activities so that homeostasis is maintained.

There are a few primary endocrine glands:

• The pituitary gland at the base of the brain
• The thyroid gland in the neck
• The four or five parathyroid glands in the tissue around the thyroid
• The two adrenal glands above the kidney against the posterior wall of the abdomen
• Certain areas of the pancreas near the stomach
• The sex glands, or gonads (testes in the male and ovaries in the female)

Various hormones are released by the endocrine glands, with each secretion causing a different reaction in the body. These include the body's growth rate, control of sex and reproductive functions, and the regulation of calcium and phosphate levels in the blood.