Receptors & Signalling

Receptor Families and How the Signal Gets Inside the Cell

Two drugs, two speeds. A puff of acetylcholine snaps a muscle taut in milliseconds; a dose of steroid takes hours to quiet an inflamed joint. Same body, same idea — a chemical binds a receptor — yet one acts faster than a blink and the other slower than a nap. The secret is that receptors come in exactly four families, and each family has its own speed. Learn the four and you can predict how fast a drug will act before you ever give it.

Second Messengers and Signal Amplification: How a Whisper Becomes a Shout

A drug the size of a fingernail's dust can set your heart racing, open your airways, or flood your blood with sugar in seconds. But most drugs never even enter the cell — they knock on a door and leave. So how does a knock on the outside become an earthquake on the inside? The answer is a relay of tiny molecular messengers that don't just pass the signal along — they multiply it thousands of times. This is the machinery of amplification, and it is why a drop can move an ocean.