What is Glands?
The central nervous system controls much of the endocrine system through the hypothalamus. The hypothalamus directs many of the body's functions through the "master endocrine gland," the pituitary gland, which in turn is able to control other endocrine glands by secreting hormones such as GH (growth hormone) and TH (thyroid-stimulating hormone). The pituitary also secretes LH (luteinizing hormone) and FSH(follicle stimulating hormone), which affect the follicles and ovaries throughout the menstrual cycle. The thyroid stimulates metabolism, and regulates blood calcium and phosphate levels, along with the parathyroid glands. The adrenal glands, located by the kidneys, secrete epinephrine (adrenaline) and norepinephrine in response to threat or danger, regulate body fluid levels, control gluconeogenesis (glucose and glycogen synthesis) in the liver, and produce sex hormones.
Insulin is a well-known hormone that is produced by the cells named Islets of Langerhans in the pancreas. Insulin triggers the absorption of glucose by cells from the bloodstream. If there is a lack of enough insulin being produced, or if there is a low number of insulin receptors, the disease known as diabetes. Another hormone produced in the pancreas is glucagon. Glucagon is a hormone that signals the liver to release stored glucose whenever the glucose, or blood sugar, levels get too low.
The gonads are the sex organs. The ovaries in females secrete estrogen and progesterone, and the testes in males produce testosterone. They are discussed further in the section on the reproductive system. The pineal and thymus glands are secondary endocrine glands, respectively producing melatonin and thymosin.