The endocrine system controls the complex activities of the body by secreting hormones into the circulatory system that influence target organs. These hormones maintain the proper balance of bodily functioning. The endocrine system consists of the pituitary gland, the thyroid gland, the parathyroid gland, the adrenal gland, the pineal gland, the pancreas, and the gonads. Each gland has its own important function.
The pituitary gland has the master role and influences the actions of the other glands. The thyroid gland secrets hormones which are vital for growth and metabolism. In birds the thyroid is important to behaviors linked to changes in daylight.
The parathyroid glands regulate the content of phosphorus and calcium in the blood and bones. Adrenal glands are divided into two parts, the medulla and the cortex. The hormones secreted by the medulla help the body in stressful situations. The pineal gland secretes melatonin, which inhibits ovarian function, and may be related to the body's circadian rhythms.
The islands of Langerhans, located in the pancreas, secrete insulin and pancreatic polypeptide. These hormones regulate carbohydrates and glucose in the blood. The gonads contain the sex hormones, which are important to the functioning of the reproductive system.
Information on the endocrine system is important to the field of veterinary technology because it can help determine why an animal is sick or not exhibiting normal behavior. If one of the glands is not functioning properly the hormone involved may be under- or over-produced which affects the maintenance of the body. .