Q: During the depolarization phase of an action potential, which ion channel opens and what is the result?

Voltage-gated Na\textsuperscript{+} channels open, allowing Na\textsuperscript{+} to enter the cell

Question 1

Which of the following best describes the three main functions of the nervous system?

Accepted Answer

Sensory input, processing and interpretation, and motor output

Question 2

A patient suffers damage to the oligodendrocytes in their central nervous system. Which of the following is the most likely consequence?

Accepted Answer

Decreased ability to transmit impulses due to loss of myelin sheaths in CNS axons

Question 3

Which equation correctly expresses Ohm's law as it applies to the flow of ions across a neuronal membrane?

Accepted Answer

$$V = I 	imes R$$

Question 4

During the depolarization phase of an action potential, which ion channel opens and what is the result?

Accepted Answer

Voltage-gated Na	extsuperscript{+} channels open, allowing Na	extsuperscript{+} to enter the cell

Question 5

Which of the following best explains why myelinated axons conduct impulses faster than unmyelinated axons?

Accepted Answer

Myelin increases membrane resistance, allowing saltatory conduction between nodes of Ranvier

Question 6

A neuron receives both excitatory and inhibitory inputs. If the sum of graded potentials at the axon hillock reaches threshold, what will occur?

Accepted Answer

An action potential will be generated and propagated down the axon

Question 7

Which glial cell type is responsible for forming the blood-brain barrier in the CNS?

Accepted Answer

Astrocytes

Question 8

Which of the following neurotransmitters is classified as a biogenic amine and is derived from the amino acid tryptophan?

Accepted Answer

Serotonin

Question 9

A patient is given a drug that blocks voltage-gated Na	extsuperscript{+} channels. What effect will this have on neuronal function?

Accepted Answer

It will prevent the generation and propagation of action potentials

Question 10

Which of the following best describes the difference between graded potentials and action potentials?

Accepted Answer

Graded potentials are local changes in membrane potential that decay with distance, while action potentials are all-or-none signals that propagate without decrement

Question 11

Which of the following equations correctly expresses the relationship between current, voltage, and resistance in a neuron?

Accepted Answer

$$I = \frac{V}{R}$$

Question 12

Which type of neuron is most likely to be found in the dorsal root ganglia of the spinal cord?

Accepted Answer

Unipolar (pseudounipolar) sensory neuron

Question 13

A patient with multiple sclerosis (MS) experiences muscle weakness and loss of coordination. What is the underlying cause of these symptoms?

Accepted Answer

Destruction of myelin sheaths in the CNS, leading to impaired nerve impulse conduction

Question 14

Which of the following best describes the role of microglial cells in the central nervous system?

Accepted Answer

They act as phagocytes, removing microorganisms and neuronal debris

Question 15

Which of the following is true regarding the refractory period of an action potential?

Accepted Answer

During the absolute refractory period, a neuron cannot generate another action potential regardless of stimulus strength

Question 16

Which of the following best explains the effect of increasing extracellular K	extsuperscript{+} concentration on the resting membrane potential?

Accepted Answer

It makes the resting membrane potential less negative (depolarizes the cell)

Question 17

Which of the following neurotransmitters is primarily inhibitory in the adult brain?

Accepted Answer

GABA (gamma-aminobutyric acid)

Question 18

A patient is experiencing numbness in their fingers after exposure to cold. Which physiological process is most likely responsible?

Accepted Answer

Reduced blood flow to neurons, slowing delivery of oxygen and nutrients

Question 19

Which of the following best describes the process of summation at the postsynaptic neuron?

Accepted Answer

Multiple EPSPs can add together to reach threshold and trigger an action potential

Fundamentals of the Nervous System and Nervous Tissue: Study Notes

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