Biology / Unit 10: Human Body Systems
10.5 The Endocrine System
Notes
The endocrine system uses hormones, chemical messengers carried in the blood, to control the body. Its effects are slower but longer-lasting than nerve signals.
- Hormones affect only target cells that have matching receptors.
- Pituitary gland: the "master gland" that controls many other glands.
- Thyroid: controls metabolism. Adrenal glands: make adrenaline for "fight or flight."
- Pancreas: makes insulin (lowers blood sugar by helping cells take in glucose) and glucagon (raises blood sugar).
- Ovaries make estrogen; testes make testosterone.
- Diabetes happens when the body does not make enough insulin or cells do not respond to it.
Practice
After a big meal, blood sugar rises. Which hormone does the pancreas release to lower it?
Insulin helps cells take glucose out of the blood.
How do hormones travel to their target cells?
Endocrine glands release hormones directly into the blood.
Compared to the nervous system, the endocrine system usually acts:
Hormones take time to travel in the blood but their effects last longer.
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