Neuroendocrine tissues are tissues that have both nervous system and hormone-producing functions. They are found in a number of locations throughout the body. Tumors develop occasionally from neuroendocrine cells in the adrenal or thyroid glands, digestive tract, or pancreas. These tumors can be benign or malignant. Even if benign, a growing tumor can disrupt nearby normal tissues and, in some cases, secrete excess hormone.
Insulinomas
The thyroid gland is a 2-lobed gland in the neck. It produces iodine-containing hormones, the most important of which are T3 and T4 , which affect many processes in the body. In general, the thyroid hormones regulate metabolic rate, or the speed at which body processes “run.” Too little hormone causes body processes to be sluggish. Too much causes them to run too fast.
The secretion of thyroid h
The pituitary gland is located near the center and bottom of the brain. It produces a number of critical hormones that control many parts of the body, including several other endocrine glands. Because of this central role, it is sometimes called a “master gland.” Because large numbers of hormones are produced by the pituitary gland, a variety of different conditions can be caused by pituitary disease or tumors. The specific illness and signs depend on the cause and t
The way in which the body processes calcium and phosphate, the function of vitamin D (which acts more like a hormone than a vitamin), and the formation of bone are all tied together into a system that involves 2 other hormones—parathyroid hormone and calcitonin—that are secreted by the parathyroid and thyroid glands.
Disorders of calcium and phosphorus metabolism that affect the skeletal system are discussed in the chapter on bone, joint, and mus
The pancreas is composed of several types of cells that have distinct functions involved in the production of hormones and digestive enzymes. The exocrine pancreas produces enzymes that are essential for the digestion of complex dietary components such as proteins, triglycerides, and complex carbohydrates. The exocrine pancreas also secretes large amounts of bicarbonate, which buffers stomach acid. Disorders of the exocrine pancreas a
The adrenal glands are located just in front of the kidneys. The adrenal gland has 2 parts—the cortex and the medulla.
The adrenal cortex is subdivided into 3 layers, and each layer produces a different set of steroid hormones. The outer layer produces the mineralocorticoids, which help to control the body’s balance of sodium and potassium salts. The middle layer produces glucocorticoids, which are involved in met
Hormones are chemical messengers that have many different functions. The effects of hormones in the body are wide-ranging and varied. Some familiar examples of hormones include insulin, which is important in the development of diabetes, and estrogen and progesterone, which are involved in the female reproductive cycle.
The endocrine system consists of a group of tissues that release hormones into the bloods