These steps of an allergic reaction are in the wrong order…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
These steps of an allergic reaction are in the wrong order.
- Histamine and serotonin are released. (ii) The allergen enters the body for the first time. (iii) IgE antibodies attach to the mast cells. (iv) The same allergen enters the body again and attaches to the IgE. (v) The person sneezes and has watery eyes. (vi) B cells make IgE antibodies.
- Write the steps in the right order.
- Name the cells that release the chemicals.
- Name two drugs that quickly reduce the symptoms.
Need a reminder? The key ideaShow
In allergy, IgE on mast cells makes the cells release histamine and serotonin. HIV is a retrovirus that destroys the helper T cells. A count below 200 helper T cells in each mm³ of blood is the sign of AIDS. In an ELISA plate a sample is positive when its reading is above the cutoff.
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. (a) The order is (ii), (vi), (iii), (iv), (i), (v).
Step 2. (b) The mast cells.
Step 3. (c) Anti-histamine drugs, and also adrenaline and steroids.
Answer: (a) (ii), (vi), (iii), (iv), (i), (v); (b) mast cells; (c) anti-histamines, adrenaline or steroids.
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