Biopsych Quiz Chapter 2

Which statement best describes the action potential? A. The level of depolarization is graded in proportion to the magnitude of the stimulus. B. An action potential occurs when the cell's membrane potential reaches threshold. C. An action potential is elicited by hyperpolarization. D. An action potential is a brief change in membrane potential from positive to negative. E. An action potential is specialized to transmit signals over only very short distances.

An action potential occurs when the cell's membrane potential reaches threshold.

Which statement best describes the electrical properties of nerve cells? A. They are exceptionally good conductors of electricity (much better than copper wires). B. They are similar in their electrical conduction properties to copper wires. C. In comparison to copper wires, they are relatively poor conductors of electricity. D. They are electron sinks; they absorb many electrons, but no electricity comes out of them. E. They are unable to conduct electricity under any circumstances.

In comparison to copper wires, they are relatively poor conductors of electricity.

Which statement about the ionic permeability of cell membranes is true? A. In resting nerve cells, the membrane is permeable to all ions. B. In resting nerve cells, the membrane is quite permeable to potassium. C. The permeability of ions is constant over time. D. In resting nerve cells, the membrane is quite permeable to sodium. E. In resting nerve cells, the membrane is quite permeable to calcium.

In resting nerve cells, the membrane is quite permeable to potassium.

In a two-compartment model of a cell with a K +- and Ca 2+-permeable membrane and a 10-fold excess of K + in the inside compartment, how would the membrane potential change if all K + ions were replaced by Ca 2+ ions? A. It would become positive. B. No potential would be generated. C. It would double. D. It would not change. E. It would be reduced by half.

It would be reduced by half.

Which state of the plasma membrane does not occur during an action potential? A. Overshoot phase B. Rising phase C. Resting phase D. Falling phase E. Undershoot phase

Resting phase

During which phase of an action potential does membrane permeability to Na + exceed membrane permeability to K +? A. Rising phase only B. Overshoot and falling phases C. Rising and overshoot phases D. All of the phases of the action potential E. Overshoot phase only

Rising and overshoot phases

Which statement about ionic distributions in nerve cells is true? A. Potassium is higher outside cells than inside cells. B. Calcium is higher inside cells than outside cells. C. Sodium is higher outside cells than inside cells. D. Chloride is higher inside cells than outside cells. E. The concentrations of all ionic species are the same for all nerve cells in all animals.

Sodium is higher outside cells than inside cells.

What would happen if the membrane became permeable to the Y + ions? A. The Y+ ions would not move. B. The Y+ ions would move into the bottom chamber, down their electrical gradient. C. The Y+ ions would move into the top chamber, down their concentration gradient. D. The Y+ ions would move into the top chamber, down their electrical gradient. E. The Y+ ions would move into the bottom chamber, down their concentration gradient.

The Y+ ions would move into the top chamber, down their concentration gradient.

A dull probe stimulates a Pacinian corpuscle. An electrode is placed midway down the axon, and action potentials are recorded. After one second, the probe is pushed with greater force. What change will occur in the recording? A. The threshold potential level will increase. B. The frequency of action potentials will increase. C. The frequency of action potentials will decrease. D. The height of action potentials will increase. E. The resting membrane potential will increase.

The frequency of action potentials will increase.

Which statement about active ion transporters is true? A. They allow ion movement down the concentration gradient. B. They are selectively permeable to certain ions. C. They are functionally similar to ion channels. D. They move certain ions against the concentration gradient. E. They move all ions against the concentration gradient.

They move certain ions against the concentration gradient.

In a two-compartment model of a cell with a K +-permeable membrane and a 10-fold excess K + in the inside compartment, the membrane potential is experimentally made more negative than the K + equilibrium potential. How would K + ions flow across the membrane? A. They would flow from the inside compartment to the outside compartment. B. They would flow in both directions at the same time in equal molar quantities. C. They would flow from the outside compartment to the inside compartment. D. There would be no flow of K+ ions. E. They would flow in both directions, but the flow would be negligible.

They would flow from the outside compartment to the inside compartment.

Under which circumstances is the Goldman equation equivalent to the Nernst equation? A. When permeability of the membrane is different for different ions B. When a membrane is permeable to only one ion C. When the membrane is permeable to positively charged ions only D. When the membrane is permeable to negatively charged ions only E. When a membrane is permeable to multiple ions

When a membrane is permeable to only one ion

The amplitude of the action potential of a given neuron is A. related to the number of synapses on the neuron. B. always the same. C. smaller if the resting potential of the neuron is lower. D. larger in response to depolarizing currents of greater magnitude. E. dependent on the magnitude of the sensory stimulus.

always the same.

An action potential occurs if current injected into a neuron _______ the neuron to reach _______ potential. A. hyperpolarizes; synaptic B. depolarizes; synaptic C. hyperpolarizes; resting D. hyperpolarizes; threshold E. depolarizes; threshold

depolarizes; threshold

In a two-compartment model of a cell with a K +-permeable membrane, at K + equilibrium potential, there is _______ flux of K + ions. A. a large inward B. a large outward C. a small outward D. no net E. a small inward

no net

The squid giant axon is useful in neuronal studies because A. the cytoplasm in the axon can be extruded, thus allowing studies of its composition. B. the axon has fewer ion channels, which simplifies the analysis of observations. C. its axon is easy to penetrate with recording electrodes because it is so long. D. multiple synapses between the nerve cells make them easy to study. E. its giant ion channels allow insertion of recording electrodes into the channels.

the cytoplasm in the axon can be extruded, thus allowing studies of its composition.

Which stimulus is most likely to evoke an action potential? A. Microelectrode insertion B. Small hyperpolarizing current pulse C. Large depolarizing current pulse D. Small depolarizing current pulse E. Large hyperpolarizing current pulse

Large depolarizing current pulse

Which experimental model did Hodgkin and Katz use in their studies of the resting membrane potential? A. Mammalian neurons B. Mammalian brain slices C. Living squid neuron D. Neurons of Aplysia species E. Neurospheres

Living squid neuron

How does membrane permeability to K + (P K) and Na + (P Na) change during an action potential? A. PK always exceeds PNa; permeability does not change for either ion. B. PK exceeds PNa at rest; PNa increases during the action potential and remains higher than PK until the next action potential, then it quickly drops. C. PNa always exceeds PK; permeability does not change for either ion. D. PNa exceeds PK at rest; PK temporarily increases during the action potential. E. PK exceeds PNa at rest; PNa temporarily increases during the action potential.

PK exceeds PNa at rest; PNa temporarily increases during the action potential.

Which type(s) of electrical signals occur(s) within the neural circuit for a spinal reflex? A. Action potential only B. Receptor potential only C. Synaptic potential only D. Receptor potential, synaptic potential, and action potential E. Receptor potential and action potential only

Receptor potential, synaptic potential, and action potential