Endocrine System
The body’s slow, chemical control network. Where the nervous system sends fast electrical signals, the endocrine system releases hormones — chemical messengers — into the bloodstream to reach targets throughout the body.
Glands and structures
Section titled “Glands and structures”- Hypothalamus — the brain region linking the nervous and endocrine systems.
- Pituitary gland — directs many other glands; the “master gland.”
- Pineal gland — produces melatonin and sets the daily rhythm.
- Thyroid gland — sets the body’s metabolic rate.
- Parathyroid glands — regulate blood calcium.
- Adrenal glands — drive the stress response and salt balance.
- Pancreatic islets — regulate blood sugar.
- Gonads — produce sex hormones (also part of the reproductive system).
Several organs not listed here — including the heart, kidneys, stomach, and fat tissue — also release hormones as a secondary role.
What it does
Section titled “What it does”- Regulation — controls metabolism, growth, the stress response, salt and water balance, and blood sugar.
- Reproduction — drives sexual development and the reproductive cycles.
- Coordination — keeps distant organs working in concert over minutes, days, or years.
Key idea
Section titled “Key idea”Most endocrine control is organized into axes — chains of glands that signal one another and use feedback loops to stay balanced. See hormonal-axes for detailed treatment of the individual axes (HPA, HPT, HPG, and others).