For each case, say whether a nerve message or a hormone is the better way, and give a reason.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
For each case, say whether a nerve message or a hormone is the better way, and give a reason. (a) Pulling a hand away from a hot iron. (b) Controlling the growth of the body over many years.
Need a reminder? The key ideaShow
Endocrine glands release hormones into the blood. The pituitary makes growth hormone, the thyroid makes thyroxin (which needs iodine), the pancreas makes insulin (which lowers blood sugar), and the adrenal glands make adrenaline (which prepares the body for danger). Feedback keeps each level right.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The hot iron. A nerve message: it is very fast, and only a few muscles need to act at once.
Step 2. Growth. A hormone, growth hormone: it reaches every cell through the blood, and its effect lasts a long time.
Answer: (a) nerves, for speed; (b) a hormone, because it reaches the whole body and acts over a long time.
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