Question 1

Which glial cell type is primarily responsible for immune defense in the central nervous system and facilitates recovery from metabolic insults?

Accepted Answer

Microglia

Question 2

A patient with Alzheimer's disease is found to have altered glial cell activity. Which cell type is most likely involved in this neurodegenerative process?

Accepted Answer

Microglia

Question 3

Which of the following best describes the function of ependymal cells in the brain?

Accepted Answer

They line fluid-filled cavities and help circulate cerebrospinal fluid

Question 4

After a peripheral neuron injury, which glial cell type can form a tube to guide regenerating axons?

Accepted Answer

Schwann cells

Question 5

Which equation predicts the membrane potential resulting from the combined contributions of all ions that can cross the membrane?

Accepted Answer

Goldman-Hodgkin-Katz (GHK) equation

Question 6

Given the GHK equation for membrane potential:
$$
V_m = 61 \log \left( \frac{P_K[K^+]_{out} + P_{Na}[Na^+]_{out} + P_{Cl}[Cl^-]_{in}}{P_K[K^+]_{in} + P_{Na}[Na^+]_{in} + P_{Cl}[Cl^-]_{out}} \right)

If $$the permeability to $$K^+$$ increases significantly, what will happen to the membrane potential?

Accepted Answer

It will become more negative (hyperpolarize)

Question 7

Which of the following is TRUE regarding graded potentials in neurons?

Accepted Answer

They can be depolarizing or hyperpolarizing and lose strength as they travel

Question 8

A mutation causes a sodium channel to remain open longer than normal. Which of the following is a likely consequence?

Accepted Answer

Prolonged depolarization of the neuron

Question 9

Which type of ion channel opens in response to physical pressure or stretch?

Accepted Answer

Mechanically gated channel

Question 10

According to Ohm's law, what happens to the current ($$I) if $$the membrane resistance ($$R) $$increases while the voltage ($$V) $$remains constant?
$$
I = \frac{V}{R}
$$

Accepted Answer

Current decreases

Question 11

Which of the following best explains why only a tiny fraction of total $$K^+$$ ions need to move to change the membrane potential by 100 mV?

Accepted Answer

The electrical potential is highly sensitive to small ion movements

Question 12

Which of the following channelopathies is caused by a defect in a chloride channel?

Accepted Answer

Cystic fibrosis

Question 13

A neuron is exposed to a drug that increases the permeability of its membrane to $$Na^+. $$What is the most likely effect on the resting membrane potential?

Accepted Answer

It will become less negative (depolarize)

Question 14

Which of the following is a property of action potentials but NOT graded potentials?

Accepted Answer

They are all-or-none signals

Question 15

Which of the following statements about ion channel gating is correct?

Accepted Answer

Different channel isoforms can have distinct gating kinetics

Question 16

A patient presents with neuropathic pain due to abnormal glial cell activity. Which glial cell is most likely implicated?

Accepted Answer

Microglia

Question 17

Which of the following best describes the role of membrane resistance ($$R_m) in $$the propagation of electrical signals in neurons?

Accepted Answer

High $$R_m$$ allows current to travel farther before dissipating

Question 18

Which of the following is NOT a function of ependymal cells?

Accepted Answer

Forming myelin sheaths

Question 19

Which of the following would most likely result from a mutation that increases the permeability of neuronal membranes to $$Cl^-$$ ions?

Accepted Answer

Hyperpolarization of the neuron

Question 20

Which of the following best explains the difference between the Nernst equation and the Goldman-Hodgkin-Katz (GHK) equation?

Accepted Answer

Nernst equation calculates equilibrium potential for a single ion, GHK considers multiple ions and their permeabilities

Neuroglia, Neuron Repair, and Electrical Signaling in Neurons

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