The Endocrine System

The endocrine system consists of glands and organs that make and release hormones. These chemical messengers travel through the bloodstream to specific target cells, where they help control processes such as growth, development, metabolism, and reproduction.

Major endocrine glands include the pituitary, thyroid, adrenal glands, pancreas, and gonads—the ovaries and testes. Hormone release responds to signals such as shifts in blood sugar or the concentration of certain minerals in the blood. The pituitary is commonly called the “master gland” because several of its hormones direct the activity of other endocrine glands. For instance, it releases thyroid-stimulating hormone (TSH), which prompts the thyroid to produce and release hormones that help regulate metabolism and growth.

The adrenal glands produce hormones such as adrenaline and cortisol that help the body respond to stress. The pancreas releases insulin and glucagon to manage blood glucose levels. The ovaries and testes produce reproductive hormones, including estrogen, progesterone, and testosterone, which support reproduction and sexual development. Other organs and tissues, including the kidneys, liver, and body fat, also produce hormones.

Through these hormonal signals, the endocrine system helps maintain the body’s internal balance, known as homeostasis. It connects the activities of different organs and tissues, coordinating bodily processes so they work together effectively.