Quiz: Transmission of Nerve Impulses

1. A neuron has a polarized membrane, which means it is relatively positive on the outside of the membrane to relatively negative on the inside. Which of the following creates this opposite charge characteristic of a neuron's membrane?
a. sodium ions on the outside and proteins on the inside
b. sodium ions on the outside and potassium ions on the inside
c. sodium and potassium ions on the outside and proteins on the inside
2. When a neuron is depolarized, the gated channels of the membrane open to allow __________ to enter the neuron. A neuron becomes hyperpolarized when the gated channels of the membrane open thus allowing __________ to exit the neuron
a. K+; Na+
b. Na+; K+
c. Na+; protein
3. A resting membrane is measured at __________ while a depolarized membrane will measure at __________.
a. +30 mV; –70 mV
b. –70 mV; +30 mV
c. 0 mV; –70 mV
4. When the sodium channels open to let sodium ions into the neuron, other gated channels open to allow __________ to exit the neuron.
a. protein
b. calcium ions
c. potassium ions
5. In order to maintain an ionic charge balance across a neuron's membrane after depolarization, what ion is moved to the outside of the membrane to maintain the ionic charge?
a. protein
b. calcium
c. potassium
6. Depolarization is the term used to describe the movement of __________ ions to the inside of a neuron while repolarization is the term used to describe the movement of __________ ions to the outside of a neuron.
a. sodium; calcium
b. sodium; potassium
c. potassium; sodium
7. __________ is the term used to describe the movement of potassium ions to the outside of a neuron, and __________ is the term used to describe excess potassium ions moving to the outside of a neuron.
a. Repolarization; hyperpolarization
b. Hyperpolarization; depolarization
c. Polarization; hyperpolarization
8. During repolarization, the sodium channels are closed. How does this affect a neuron?
a. The neuron cannot respond to new stimuli.
b. The neuron becomes more sensitive to new stimuli.
c. It does not affect the neuron; it can still respond to stimuli.
9. When a neuron is hyperpolarized, it __________.
a. cannot respond to new stimuli
b. becomes more sensitive to new stimuli
c. responds as normal and is not affected at all
10. Once a gated channel is open, positive ions will enter through the channels to get inside the neuron. Which of the following can cause the gated channels to open?
a. stimulus
b. an impulse
c. an action potential
11. Once the gated channels are open and positive ions begin to enter the neuron, we have the start of a(n) __________.
a. stimulus
b. impulse
c. resting potential
12. Since depolarization results in positive ions entering into the neuron, there will be a voltage change. Which of the following correctly depicts the voltage value going from a resting neuron to a depolarized neuron?
a. +10 mV to +30 mV
b. –70 mV to 0 mV
c. +30 mV to –70 mV
13. When discussing a neuron's activity, we discuss graded potentials and action potentials. A graded potential arises in all of the following EXCEPT __________.
a. axons
b. somas
c. dendrites
14. Which of the following would be the best and most accurate way of describing an action potential?
a. If there are enough stimuli, the sodium ion channels (gates) will open only in the dendrite area. There have to be additional stimuli to get the channels to open in the axon area.
b. If there are enough stimuli, the sodium ion changes (gates) will open in succession all the way down an axon.
c. If there are enough stimuli, the sodium ion channels (gates) will open all at the same time within the axon.
15. Which of the following statements is FALSE?
a. If the stimulus reaches the threshold level, depolarization will occur.
b. If the stimulus does not reach the threshold level, depolarization will not occur.
c. If the stimulus almost reaches the threshold level, depolarization will only occur half way down the axon.
16. Which of the following statements is true?
a. An action potential occurs if the membrane goes from +30 mV to –70 mV.
b. An action potential occurs if there are more sodium ions than potassium ions on the inside of an axon.
c. An action potential occurs if there are more potassium ions than sodium ions on the inside of an axon.
17. Hyperpolarization of a neuron occurs when the inside becomes more negatively charged than when it was at a resting potential value. Which of the following will NOT cause hyperpolarization?
a. massive entrance of sodium ions into the axon
b. massive entrance of chloride ions into the axon
c. massive exit of potassium ions out of the axon

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