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The endocrine system is one of the body’s main systems for communicating, controlling and coordinating the body’s functioning. It works closely with the nervous system, reproductive system, kidneys, gut, liver, pancreas and fat to help maintain and control energy levels, reproduction, growth and development, internal balance of body systems (homeostasis), and responses to surroundings, stress and injury.

The endocrine system is comprised of a network of glands and organs that produce, store and secrete hormones. Like a factory, endocrine glands and endocrine-related organs produce hormones and release them through the bloodstream to specific areas throughout the body and brain. These hormones dictate a body’s metabolic function.

Adrenal Glands

Weighing only a fraction of an ounce each, with a length of just one-to-two inches, they secrete more than 36 different hormones. These triangular-shaped glands, which are perched on each of the kidneys, secrete steroid hormones directly into the bloodstream and can be divided into two distinct organs. The outer region, the adrenal cortex, secretes corticosteroids steroids that regulate the body’s metabolism, the balance of salt in water in the body, the immune system and sexual functions. These hormones importantly affect the way energy is stored and food is used, on chemicals in the blood and on characteristics such as hairiness and body shape. The smaller, inner region, the adrenal medulla, is part of the sympathetic nervous system and is the body’s first lines of defense and response to physical and emotional stress – such as “fight or flight” hormones as instructed by the nervous system in response to fear and anger. The adrenal medulla produces hormones called catecholamines, such as adrenaline, that help the body cope with physical and emotional stress by increasing the heart rate and blood pressure.

Pancreas

It is a long, tapered gland that lies across and behind the stomach. This gland secretes digestive juices that break down fats, carbohydrates, proteins and acids. It also secretes biocarbonate, which neutralizes stomach acid as it enters the duodenum. Some cells in the pancreas secrete hormones that regulate the level of glucose in the blood, namely, glucagon and insulin.

Pineal Gland

Located in the middle of the brain, it secretes the hormone melatonin, which may help regulate the wake-sleep cycle of the body. Some researchers theorize other hormones originate from this gland but this is not yet universally recognized.

Pituitary Gland & Hypothalamus

Located in the center of the skull just behind the bridge of the nose and the size of a pea, is an important link between the nervous and endocrine systems and releases many hormones that affect growth, sexual development, metabolism and the reproductive system. It is divided into two parts – the anterior and posterior lobes. The hypothalamus is a tiny cluster of brain cells just above the pituitary gland that transmits messages from the body to the brain.

Reproductive Glands: The Ovaries and Testes

In addition to producing eggs in females, the ovaries produce the female sex hormones estrogen and progesterone. Located in the male scrotum, the testes secrete androgen hormones, such as testosterone, which affect male characteristics and sperm production.

Thymus

Situated in the upper part of the chest behind the breastbone with two lobes that join in front of the trachea, the thymus is part of the immune system. Each lobe is made of lymphoid tissues consisting of tightly packed white blood cells and fat. Its function is to transform lymphocytes (white blood cells developed in the bone marrow) into T-cells (cells developed in the thymus), which are then transported to various lymph glands to help fight infections and disease.

Thyroid and Parathyroid Glands