You have seen that you can use combinations of agonists and antagonists to find out about:
- 
The types of receptor present in a tissue
 
- Where new agonists and antagonists act in a tissue
 
 
In the next screen, you are given a choice of agonists and antagonists.  Your aim is to use combinations of these drugs to find out, as far as possible, what receptors are present in the guinea pig ileum.