A–Z
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A way into the science.

Five connected ideas, from the basics of a cell to reading a human study. Follow them in order or start with the question that brought you here.

About 26 minutes in total.

1

Start with a cell

Get the basic picture of what a cell is before following a signal through it.

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Sending cellReceiving cellA chemical signal
2

Cells exchange signals

Understand the sender, messenger and receiving cell.

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Sending cellReceiving cellA chemical signal
3

Receptors make a signal meaningful

See how a binding interaction can influence a response.

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Chemical messengerReceptorCell membraneA response inside the cell
4

Medicines change the response

Distinguish activating, blocking and other target interactions.

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TargetTissueOutcomeDIFFERENT LEVELS OF EXPLANATION
5

An experiment tests the idea

Move from a biological hypothesis to a clinical comparison.

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A DESIGNED COMPARISONGroup AGroup BRandom allocation

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Further reading

Trusted external resources selected to help explain this page. They open in a new tab.

  • What is a cell? ↗MedlinePlus Genetics / U.S. National Library of Medicine · Checked 3 Nov 2026A beginner-friendly overview of cells and the parts that help them function.
  • Glossary of common clinical research terms ↗National Institutes of Health · Checked 3 Nov 2026Plain-language definitions for terms used when reading studies in people.
Explanation