A neurophysiologist is investigating nerve reflexes in two different animals: a crab and a fish. Action potentials are found to pass more rapidly along the fish's neurons. What is the most likely explanation

Option B, Unlike the crab, the fish's axons are wrapped in myelin.

Explanation:

Options for the question

A) The fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do.

B) Unlike the crab, the fish's axons are wrapped in myelin.

C) There are more ion channels in the axons of the crab compared with fish axons.

D) Unlike the crab, the fish's axons are wrapped in myelin, and the fish's axons are smaller in diameter; small axons transmit action potentials faster than large axons do.

solution

The signal conductivity of an axon increases when it is coated with an insulating material. Myelin is layer of fatty substance that insulated the axon and hence increases its conductivity by reducing or stopping the loss of ions responsible for conducting information. Not only this myelin also reduces the capacitance of the neuron by reducing the agitated negative ions which in turn attracts the positive ion.

Hence, option B is correct

Answer: Unlike the crab, the fish's axons are wrapped in myelin.

Explanation:

The neurophysiologists is investigating about action potential in the fish and a crab.

he found that the action potentials are moving faster in the fishes as compared to that of the crab.

This is because the neurons of the fishes are covered with myelin sheath and crabs's neurons does not have myelin coating on it.

The main function of myelin sheath is to enhance the effect of signal transmission and protect the axon.