Question

21
what is myelin?
multiple choice
a substance released from a neuron that travels to another neuron.
a form of chromatophilic substance that fills schwann cells.
a substance produced in response to bacterial infection.
layers of lipids and proteins that wrap around an axon

Explanation:

Myelin is formed by Schwann cells (in the peripheral nervous system) or oligodendrocytes (in the central nervous system). It consists of layers of lipids and proteins that wrap around an axon. This myelin sheath insulates the axon, allowing for faster nerve impulse conduction (saltatory conduction).

• The first option describes a neurotransmitter, not myelin.
• Chromatophilic substance (Nissl bodies) is related to protein synthesis in neurons, not myelin.
• The third option is incorrect as myelin is not a response to bacterial infection.

Answer:

Layers of lipids and proteins that wrap around an axon.