Question

The axons from touch fibers are A fibers, and the axons from pain fibers are C fibers. When you stub your toe, which would you expect to perceive first?

1) pain
2) your toe touching something
3) both would be perceived at the same time
4) neither would be perceived

Answer 1

The first perception experienced when stubbing your toe would be touch, conveyed via faster, myelinated A fibers, rather than pain, which is transmitted by slower, unmyelinated C fibers. Therefore, touch is typically felt before pain. Therefore, the correct option is 2).

Step-by-step explanation:

When you stub your toe, the perception you would expect to perceive first is the touch from the A fibers rather than the pain from the C fibers. A fibers are associated with the sensation of light touch and are myelinated, which allows for faster transmission of nerve impulses compared to the unmyelinated C fibers that transmit pain. Because myelination significantly increases the speed of nerve conduction, stimuli carried by A fibers reach the cerebral cortex more quickly than those carried by C fibers, leading to an earlier perception of touch.

Furthermore, the conscious perception of pain can be delayed due to the time it takes for the sensations to travel along the slower C fibers to reach the cerebral cortex. This process, known as the propagation of the axon potential, is due to the all-or-none property where action potentials maintain their strength traveling down the axon without fading. Therefore, touch is typically perceived before pain, meaning the correct option in the final answer is option 2) your toe touching something.