Biopsych quiz 2

Which experimental model did Hodgkin and Katz use in their studies of the resting membrane potential? a. Living squid neuron b. Neurons of Aplysia species c. Mammalian neurons d. Mammalian brain slices e. Neurospheres

a. Living squid neuron

Which state of the plasma membrane does not occur during an action potential? a. Resting phase b. Rising phase c. Overshoot phase d. Falling phase e. Undershoot phase

a. Resting phase

Under which circumstances is the Goldman equation equivalent to the Nernst equation? a. When a membrane is permeable to only one ion b. When a membrane is permeable to multiple ions c. When the membrane is permeable to positively charged ions only d. When the membrane is permeable to negatively charged ions only e. When permeability of the membrane is different for different ions

a. When a membrane is permeable to only one ion

In a two-compartment model of a cell with a K+ and Ca2+ 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 Ca2+ ions? a. It would double. b. It would be reduced by half. c. It would not change. d. It would become positive. e. No potential would be generated.

b. It would be reduced by half.

During which phase of an action potential does membrane permeability to Na+ exceed membrane permeability to K+? a. Rising phase only b. Rising and overshoot phases c. Overshoot phase only d. Overshoot and falling phases e. All of the phases of the action potential

b. Rising and overshoot phases

Which statement about ionic distributions in nerve cells is true? a. Potassium is higher outside cells than inside cells. b. Sodium is higher outside cells than inside cells. c. Chloride is higher inside cells than outside cells. d. Calcium is higher inside cells than outside cells. e. The concentrations of all ionic species are the same for all nerve cells in all animals.

b. Sodium is higher outside cells than inside cells.

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 height of action potentials will increase. b. The frequency of action potentials will increase. c. The frequency of action potentials will decrease. d. The resting membrane potential will increase. e. The threshold potential level will increase.

b. The frequency of action potentials will increase.

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 from the outside compartment to the inside compartment. c. There would be no flow of K+ ions. d. They would flow in both directions at the same time in equal molar quantities. e. They would flow in both directions, but the flow would be negligible.

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

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

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

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 unable to conduct electricity under any circumstances. e. They are electron sinks; they absorb many electrons, but no electricity comes out of them.

c. 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. The permeability of ions is constant over time. c. In resting nerve cells, the membrane is quite permeable to potassium. d. In resting nerve cells, the membrane is quite permeable to sodium. e. In resting nerve cells, the membrane is quite permeable to calcium.

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

What would happen if the membrane became permeable to the Y+ ions? a. The Y+ ions would move into the bottom chamber, down their concentration gradient. 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 not move.

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

An action potential occurs if current injected into a neuron _______ the neuron to reach _______ potential. a. depolarizes; synaptic b. hyperpolarizes; synaptic c. depolarizes; threshold d. hyperpolarizes; threshold e. hyperpolarizes; resting

c. 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. no net d. a small inward e. a small outward

c. no net

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

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

Which stimulus is most likely to evoke an action potential? a. Small hyperpolarizing current pulse b. Large hyperpolarizing current pulse c. Small depolarizing current pulse d. Large depolarizing current pulse e. Microelectrode insertion

d. Large depolarizing current pulse

How does membrane permeability to K+ (PK) and Na+ (PNa) change during an action potential? a. PNa always exceeds PK; permeability does not change for either ion. b. PK always exceeds PNa; permeability does not change for either ion. c. PNa exceeds PK at rest; PK temporarily increases during the action potential. d. PK exceeds PNa at rest; PNa temporarily increases during the action potential. e. 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.

d. 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. Receptor potential only b. Action potential only c. Synaptic potential only d. Receptor potential and action potential only e. Receptor potential, synaptic potential, and action potential

e. Receptor potential, synaptic potential, and action potential

Which statement about active ion transporters is true? a. They are selectively permeable to certain ions. b. They are functionally similar to ion channels. c. They allow ion movement down the concentration gradient. d. They move all ions against the concentration gradient. e. They move certain ions against the concentration gradient.

e. They move certain ions against the concentration gradient.

The amplitude of the action potential of a given neuron is: a.larger in response to depolarizing currents of greater magnitude. b. dependent on the magnitude of the sensory stimulus. c. related to the number of synapses on the neuron. d. smaller if the resting potential of the neuron is lower. e. always the same.

e. always the same.