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You are recording action potentials in a nerve cell in a petri dish in the laboratory. The only difference between your setup in the lab and the normal condition in the body is that the cell is now surrounded by a solution that has a higher concentration of sodium ions than normal. What are you most likely to observe?

A. The resting membrane potential is more hyperpolarized than in the body

B. The action potentials peak at a lower voltage than in the body

C. The action potentials peak at a higher voltage than in the body

D. A and B are both correct

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Irving Heathcote
Irving HeathcoteLv2
28 Sep 2019

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Related questions

1. The plasma membrane of rod and cone cells are

a) At resting potential in the dark and deploarized in thelight

b) At resting pootential in the dark and hyperpolarized in thelight

c) Depolarized in the dark and hyperpolarized in the light

d) Hyperpolarized in the dark and at resting potential in thelight

e) Hyperpolarized in the dark and depolarized in the light

2. The equilibrium potential of K+ ions in nerve cells is about-90mV. The membrane potential of a typical nerve cells at rist is-70mV. Therfore

a) Increasing the permeability of a resting neuronal membrane toK+ ions will increase the membrane potential (that is, make it morenegative, inside with respcect to outside)

b) In nerve cells at rest, there is a net diffusion of K+ ionsout of the cell

c) Increasing the membrane potential of a nerve cell would slowthe diffusion of K+ ions out of it.

d) K+ is not the only ion that is permeable at rest

e) All of the above

3. Which of the following is responsible for the replarizingphase of the action potential?

a) Voltage-gated Na+ channels are opened.

b) The Na+-K+ pump restores the ions to theri original restingstate.

c) The permeability to Na+ increases greatly.

d) ATPase destroys the energy supply that was maintaining theaction potential at its peak.

e) The permeability to K+ increases greatly while that to Na+decreases

4. The Relative refractory period of an axonm conincides withthe period of

a) Activation and inactivatioin of voltage-gated Na+channels

b) Increased Na+ flux into the cell

c) Increased K+ flux into the cell

d) Increased K+ flux out of the cell

e) Increased Na+ flux out of the cell

5. The plasma membranes of rod and cone cells are

a) At resting potential in the dark and epolarized in thelight

b) At resting potential in the dark and hyperpolarized in thelight

c) Depolarized in the dark and hyperoplarized in the light

d) Hyperpolarized in the dark and tat resing potential in thelight

e) Hyperpolarized in the dark and depolarized in the light

What would be most strongly affected by a drug that inhibited the opening of voltage-gated potassium channels (also known as delayed rectifiers)?

A. Falling phase of an action potential

B. Rising phase of an action potential

C. Resting membrane potential

D. Threshold for an action potential

Why does the voltage during the undershoot phase of the action potential become more negative than the resting membrane potential?

A. During the undershoot potassium ions are flowing into the cell due to the reversal of the potassium concentration gradient occurring during the action potential

B. The undershoot phase results from a delay in the activation of sodium channels, resulting in some sodium channels being open after the voltage-gated potassium channels have closed. C. The potassium conductance is higher during the undershoot than during the resting membrane potential.

D. The concentration gradient for potassium has been reversed as a result of the action potential, and the undershoot phase lasts until this the concentration gradient is restored.

Santiago Ramon y Cajal’s theory of dynamic polarization refers to the:

(a)membrane potential of a neuron at rest.

(b)membrane potential of a neuron firing action potentials.

(c)opening and closing of gated channels in the membrane.

(d)one way flow of information in neurons from dendrites to axon terminals.

(e)one way flow of information in neurons from axon terminals to dendrites.

Over the course of scientific history, there are many examples of scientists reaching the right conclusion for the wrong reasons. When Schwann first proposed that the nervous system was made of individual cells, he based it on observations of:

(a)synapses.

(b)dendrites

(c)axon terminals.

(d)astrocytes.

(e)Nodes of Ranvier.

The synaptic cleft was finally seen in the 1950s. What prevented scientists from seeing it earlier?

(a)The resolution of the light microscope.

(b)They were looking in the wrong place.

(c)Their tissue was not appropriately stained.

(d)Myelination of the axons.

(e)all of the above

The resting membrane potential of a neuron is approximately:

(a) +65 V

(b) +65 mV

(c) -65 V

(d) -65 mV

What is largely responsible for the resting membrane potential in a neuron?

(a)Axonal insulation by myelin

(b)Voltage-Gated Sodium Channels

(c)The Action Potential

(d)Potassium Leak Channels

Which of the following would DECREASE the propagation velocity of an action potential down an axon?

(a)Increase in axon diameter

(b)Increase myelination between nodes of Ranvier

(c)Remove myelination between nodes of Ranvier

(d)Decrease density of voltage-gated Na+ channels except at the Nodes of Ranvier

The resting membrane potential of a neuron can be estimated using the:

(a)Nernst equation

(b)Goldman equation

(c)Hodgkin and Huxley equation

(d)Ohm’s law

18. What would happen to the resting membrane potential of a neuron if you added K+ to the extracellular fluid?

(a)Resting membrane potential would increase (become more positive)

(b)Resting membrane potential would decrease (become more negative)

(c)Resting membrane potential would not change

(d)Resting membrane potential would be abolished

. Which of the following statements is FALSE for Graded Potentials

(a)Magnitude changes with magnitude of triggering stimulus

(b)Magnitude decreases with distance from initial site

(c)Cannot be summed

(d)No refractory period

In the nervous system, the strength of the stimulus is coded into:

(a)The frequency of action potentials generated

(b)The amplitude of action potentials generated

(c)Both the frequency and amplitude of action potentials generated

(d)The duration of individual action potentials generated

Ion movement during both the depolarization and repolarization phases of an action potential are the result of:

(a)active transport pumps along the neuron membrane.

(b)diffusion of ions down their electrochemical concentration gradients.

(c)negative feedback loops.

(d)All of the above

At the peak of the action potential, the membrane potential is:

(a)Exactly at the Na+ equilibrium potential

(b)Greater (more positive) than the Na+ equilibrium potential

(c)Above 0 mV but less positive than the Na+ equilibrium potential

(d)0 mV

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