Endocrine System and Hormones
Hormones are chemical messengers in the blood.
About this topic
The endocrine system uses hormones, chemical messengers released by glands into the blood, to coordinate slower, longer-lasting responses than nerves. Glands include the pituitary (the "master gland"), thyroid (metabolism), adrenal (adrenaline), pancreas (insulin) and ovaries/testes (sex hormones).
Hormones act only on target cells with matching receptors. Negative feedback keeps levels balanced. Nervous responses are fast and brief, whereas hormonal ones are slower and longer.
Adrenaline is released by the adrenal glands during fear or excitement, raising heart rate and sending glucose to muscles within seconds, while growth hormone from the pituitary acts over years. Thyroxine from the thyroid controls metabolic rate, and the sex hormones control puberty. Hormones work only on target cells that have matching receptors.
Many hormones are controlled by negative feedback. Problems include diabetes, where insulin is lacking or ineffective, and goitre, where lack of iodine swells the thyroid. Hormones are used medically, such as in the contraceptive pill and in fertility treatment. Students tend to confuse nerves and hormones: nerves are fast and short-lived through electrical impulses; hormones travel in blood and have slower, longer effects.
Key ideas
- Glands such as the pituitary and thyroid
- Slower but longer lasting than nerves
- Insulin controls blood sugar
Quick check
Use cases: where Endocrine System and Hormones helps
- Homework: review the key idea behind Endocrine System and Hormones before you start a problem set.
- Exam revision: use the quick check to test whether you can recall Endocrine System and Hormones without notes.
- Visual learning: play with the interactive lab to see how Endocrine System and Hormones changes when you adjust its inputs.
- Teaching a friend: explain Endocrine System and Hormones in your own words, then compare your version with the key ideas.
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Frequently asked questions
What is Endocrine System and Hormones?
Hormones are chemical messengers in the blood.
What will I learn in Endocrine System and Hormones?
Glands such as the pituitary and thyroid. Slower but longer lasting than nerves. Insulin controls blood sugar.
Is Endocrine System and Hormones part of Biology?
Yes. It is one of 150 Biology topics on LearnViz HighSchoolEdu, with 3 key ideas, a live animation and a quick check.
Does the Endocrine System and Hormones lab work on a phone or tablet?
Yes. The animation resizes to fit your screen and supports touch, so you can drag, tap and slide with your finger.
How should I study Endocrine System and Hormones?
Read the summary and key ideas first, play with the interactive lab to see the idea in motion, then answer the quick check. If you get a question wrong, go back to the key idea it tests.
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