What Determines Whether a Cell Is a Target Cell for a Particular Signal Molecule?

Epinephrine is a hormone that helps trigger the "fight or flight" response in your body.

Cells in your body communicate by releasing signaling molecules like hormones. The signaling molecules induce responses in other cells in turn, like the muscle contractions in your fingers triggered by release of neurotransmitters from nerve cells as you type.

Types

Cells may secrete signals meant for nearby cells, a type of communication called paracrine signaling. Other intercellular mechanisms of communication include cell-cell recognition, synaptic signaling and endocrine signaling.

Function

Signal molecules bind to receptors, molecules that have the right shape to attach to the incoming signal molecule. A cell will only respond to the signal if it has a receptor that can recognize the signal molecule.

Features

Once the signal molecule binds to the receptor, it changes the receptor's shape so that the receptor is able to trigger a cascade of events inside the cell. The specific series of events triggered by the signal molecule may differ depending on the cell.

References

• "Biology"; Campbell, Reece, Urry, Cain, Wasserman, Minorsky, Jackson; 2008