A gland releases 800 units of a hormone into the blood and then stops…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A gland releases 800 units of a hormone into the blood and then stops. The hormone has a half-life of min.
- How many units are left after min?
- How many units are left after min?
- How many units are left after min?
Need a reminder? The key ideaShow
Hormones are non-nutrient messengers made in trace amounts by ductless glands. After a gland stops, the amount in the blood halves in each half-life. The hypothalamus makes releasing and inhibiting hormones that reach the anterior pituitary by the portal system. Oxytocin and vasopressin are made in the hypothalamus and released from the posterior pituitary.
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.
Given. Start: units. Half-life: min.
Plan. Find the number of half-lives, then halve that many times.
Step 1. min. half-lives. units.
Step 2. min. half-lives. units.
Step 3. min. half-lives. units.
Answer: units; units; units.
Check. Each answer is smaller than the one before, and each is exactly half of the amount one half-life earlier.
Watch out. The amount falls by half in each half-life, not by the same number of units each time.
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