Cameo

The Soccer Mom by Bolognese, Coronel, Intorre and Stephens

Part III—Diagnostic Tests


Dr. Thrush looked over the results of Phyllis’s Magnetic Resonance Imaging (MRI) and evoked potential tests. She was thinking how glad she was that Steven had accompanied Phyllis on this visit as she showed them the MR images of Phyllis’ brain.

“The machine took pictures of Phyllis’ brain in slices. The dark areas are the brain tissue, Phyllis, and the white areas in the middle and around the outside are the cerebrospinal fluid.”

“Is that normal? Am I OK?” Phyllis asked. “And what are those little white dots in the tissue?”

“The white dots are what concerned me,” replied the doctor. “So we did another type of MRI, called dark fluid, so that your cerebrospinal fluid would not show up white.”

“But I still see the white dots in my brain tissue. What does that mean?”

The doctor looked down, knowing that this was never an easy thing to tell a patient.

“I am afraid that this indicates that there are plaques or scars in your brain, and that you may have multiple sclerosis.”

Tears began to form in her eyes as Phyllis squeezed her husband’s hand.

“I am afraid that the evoked potential test and the elevated levels of myelin basic protein in you cerebrospinal fluid indicate the same thing.”

Flow diagram

Questions

  1. Test your knowledge of the function of chemical synapses by filling in the flow diagram to the right.
  2. What type of cell is myelin?
  3. What is the function of myelin in nerve cells?
  4. In myelinated axons, where are action potentials generated?
  5. Where, then, are voltage gated sodium channels concentrated in myelinated axons?
  6. What happens to myelin in people who suffer from multiple sclerosis?
  7. Why is there an elevated level of myelin basic protein in the cerebrospinal fluid?
  8. What would be the effect on action potential conduction at a region of axon where the disease had its effect?
  9. What effect would this have on the coordination of movements if this took place in areas involved in motor control of finger movements?

Go to Part IV—“The Diagnosis”

Originally published at http://www.sciencecases.org/soccer_mom/soccer_mom3.asp

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