Questions: Question 17 (1 point) Professor Cook is lecturing on the importance of the myelin sheath. He told the class that - a) myelin is the only structure that can prevent action potentials from traveling the wrong direction. b) the fatty nature of the myelin speeds up the action potential down the length of the axon c) the fatty nature of myelin provides storage for key nutrients for the neuron d) myelin increases the strength of the action potential

The answer is the second one (b): the fatty nature of the myelin speeds up the action potential down the length of the axon.

Explanation for each option:

a) Myelin is the only structure that can prevent action potentials from traveling the wrong direction.

• Incorrect. While myelin does play a role in the efficient transmission of action potentials, it is not the only structure that prevents action potentials from traveling in the wrong direction. The refractory period of the neuron also ensures that action potentials only travel in one direction.

b) The fatty nature of the myelin speeds up the action potential down the length of the axon.

• Correct. Myelin sheaths are composed of fatty substances that insulate the axon and allow for faster transmission of electrical signals through a process called saltatory conduction, where the action potential jumps from one node of Ranvier to the next.

c) The fatty nature of myelin provides storage for key nutrients for the neuron.

• Incorrect. Myelin does not serve as a storage site for nutrients. Its primary function is to insulate the axon and speed up the transmission of electrical signals.

d) Myelin increases the strength of the action potential.

• Incorrect. Myelin does not increase the strength of the action potential. The strength of an action potential is generally constant; myelin primarily affects the speed at which the action potential travels along the axon.

Summary: The correct answer is b) the fatty nature of the myelin speeds up the action potential down the length of the axon. This is because myelin sheaths facilitate faster transmission of electrical signals through saltatory conduction.