Biology / Unit 4 Bio 0767 short lesson, about 20 seconds
Synaptic Signaling, a Paracrine Case
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The idea
A synapse is the small gap between two nerve cells where a presynaptic cell releases neurotransmitters, a paracrine ligand, triggering a response in the postsynaptic cell.
In practice
The 20-to-40-nanometer synaptic gap lets a neurotransmitter reach its receptor almost instantly, enabling a hand-off-a-hot-stove reflex.
Where people slip
A nerve impulse travels electrically inside one cell; only the crossing between cells is chemical.
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