Ouch! How Getting Hurt Hurts

If you’ve dropped a heavy object on your toe or slammed your finger in the door, you’ll notice that a sharp pain happens immediately, followed by a dull, throbbing ache later. Why the lag? It’s because two kinds of neurons—cells that relay signals between your body and brain—are working. The key difference between these neurons is how fast they transmit signals back to your brain, and the speed depends on whether the neuron is covered by a membrane called myelin.

Neurons are star-like shaped with long tendrils coming out. One finalist from The Physiological Society’s BioBake—a baking competition in which participants create physiology-themed baked goods—diagrammed a neuron out of gingerbread and Swiss rolls.

Credit: Amy Bradley / The Physiological Society

Credit: Amy Bradley / The Physiological Society

The star-shaped cookie is the neuron’s cell body which contains the proteins and machinery the neuron needs to work. Neurons receive signals— for instance, pain from your toe—at the cell body or at the dendrites, the points on the gingerbread cell body. The electrical signal travels down the axon, the cord portion with the Swiss rolls, and comes out the end of the axon to go onto the next neuron back to the brain. Neurons also pass signals from the brain to the body.

Many neurons have axons that are wrapped with layers of myelin—the Swiss rolls in this gingerbread neuron. The wrapped sections are spaced out like the Swiss rolls, with gaps in between. On a myelinated neuron, instead of passing down the entire length of the axon, the electrical signal hops from one gap to the next, going much faster. You will notice how much faster myelinated neurons are when you injure yourself. The sharp pain in your toe immediately after dropping a heavy object on it is from signals coming on myelinated neurons. The dull pain you feel later is from signals traveling unmyelinated neurons.

See what other physiological systems look like as baked goods. Check out this year’s BioBake entries and vote for your favorite one tomorrow and Friday.

Maggie KuoMaggie Kuo, PhD, is the former Communications and Social Media Coordinator for APS. Catch more of her writing in the Careers Section of Science Magazine.

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