Biology I - Nervous System - Gray and White Matter

Q: Why is white matter white?

A: It contains myelinated axons rich in lipid.

Q: What’s the structural difference between cortex and nuclei in the brain?

A: Cortex is outer gray matter; nuclei are deep gray matter clusters.

Q: Where is gray matter located in the spinal cord?

A: Centrally, in an H-shaped configuration.

Q: What do “tracts” in white matter represent?

A: bundles of axons that travel to the same location

Q: Why does damage to gray matter often cause loss of function?

A: It contains neuron cell bodies essential for processing.

Q: How does the brain’s gray-white organization differ from the spinal cord?

A: Brain: gray outside, white inside; spinal cord: opposite.

Q: A stroke damages a deep brain nucleus. What tissue type is affected?

A: Gray matter.

Q: How do Schwann cells contribute to faster nerve conduction?

A: They form myelin in the PNS, enabling saltatory conduction.

Q: Which cells produce myelin in the CNS and PNS, respectively?

A: Oligodendrocytes (CNS) and Schwann cells (PNS).

Q: What is saltatory conduction?

A: Action potentials "jump" between nodes of Ranvier, increasing conduction speed.

Q: What are nodes of Ranvier and why are they important?

A: Gaps between myelin sheaths where ion channels regenerate the action potential.