The Endocrine System

The endocrine system controls aspects of the body that occur over longer periods of time. While the nervous system can detect, process and respond to a stimulus in a fraction of a second and then move on to the next stimulus, the endocrine response can take place over minutes, hours, days or even years.

Endocrine glands throughout the body make specific hormones.
- Hormones travel through the blood and stimulate cells in a different part of the body to respond.
The benefit of endocrine responses is that they can last longer than nervous signals.
- It can take many minutes to bring blood sugar back to normal levels.
- It can take years for growth hormone to stimulate bones and muscles to expand.

Endocrine Glands

The poster child of the endocrine system is the pancreas and how it regulates blood sugar to maintain homeostasis, but there are other glands that release hormones. The following is a list of endocrine glands and the hormones they release.

Pancreas - controls the amount of glucose in the blood
- Insulin - lowers blood sugar
- Glucagon - increases blood sugar
Hypothalamus - links the nervous system (brain) to the endocrine system (pituitary gland), but also makes its own hormones
- Oxytocin - critical for childbirth, but also helps to form social bonds
Pituitary Gland - releases hormones that affect other endocrine glands, but also makes...
- Growth Hormone - stimulates growth of skeletal, muscle and other tissues.
Thyroid Gland - controls general metabolism and calcium levels in the blood
- T3/T4 - increase metabolism
- Calcitonin - lowers blood calcium
Parathyroid Gland - helps control calcium
- Parathyroid hormone - raises blood calcium
Adrenal Glands - help the body deal with stress
- Adrenaline - short term stress; speeds up blood flow and breathing to maximize physical activity
- Cortisol - long term stress; increases blood glucose, decreases inflammation/immune response
Testes - influence male reproduction
- Testosterone - stimulate the production of sperm and male secondary sex characteristics
Ovaries - influence female reproduction
- Estrogen/Progesterone - development and maintenance of eggs, reproductive cycle, and female secondary sex characteristics