TEAS® Science Study Guide
Endocrine System
The endocrine system releases hormones into the bloodstream to regulate body processes.
Nervous vs. endocrine: the nervous system sends fast electrical signals for immediate responses. The endocrine system sends slower chemical signals that produce longer-lasting effects. Both coordinate the body; they just work on different timescales.
Major glands and what they release
- Pituitary — The "master gland." Controls other glands. Growth hormone.
- Thyroid — Regulates metabolism. Needs iodine.
- Adrenal glands — Sit on the kidneys. Release adrenaline (fight-or-flight) and cortisol (stress).
- Pancreas — Insulin lowers blood sugar; glucagon raises it. (The pancreas is also a digestive organ.)
- Ovaries / testes — Estrogen and progesterone / testosterone.
Negative feedback
Most hormones are controlled by negative feedback: when a level gets too high, the body acts to bring it back down, and vice versa. Blood sugar is the classic example — eat, blood sugar rises, insulin is released, blood sugar falls. This is how the body maintains homeostasis, a stable internal environment.
Terms to know
- Hormone — Chemical messenger released into the blood.
- Homeostasis — Maintaining stable internal conditions.
- Negative feedback — A response that reverses a change and restores balance.
- Insulin — Lowers blood glucose. Glucagon — Raises it.
What the TEAS asks most
- Which hormone lowers blood sugar? Insulin.
- Which gland is the "master gland"? Pituitary.
- Which gland controls metabolism? Thyroid.
- What is negative feedback? A mechanism that reverses a change to restore homeostasis.