So, the greater the number of receptors a body part has, the more sensitive it will be.

At this point, they were designated as a separate class of receptors.

But cancer cells have a much higher concentration of receptors.

Not least among the puzzles is the number of different receptors observed.

The first is to clarify the role of particular receptors in individual illnesses.

They discovered that only the deeper cells had the right type of receptors.

A fourth group of receptors has recently been identified in the brain, gut and heart.

'It must be that we have the same kinds of receptors,' she said.

However, no single set of receptors is solely responsible for the information the brain uses to control eating.

That search led them to discover a family of closely related receptors far bigger than they had expected.