Suppose that in a certain neuron, negatively charged protein molecules found in the intracellular compartment were suddenly able to diffuse through the cell membrane freely. What would be the result on this cell's resting membrane potential and action potential threshold? A) The resting potential would hyperpolarize and the action potential threshold would not change. B) The resting potential would depolarize and the action potential threshold would decrease. C) The resting potential would depolarize and the action potential threshold would not change. D) The resting potential would hyperpolarize and the action potential threshold would increase.

Suppose that in a certain neuron, negatively charged protein molecules found in the intracellular compartment were suddenly able to diffuse through the cell membrane freely. What would be the result on this cell's resting membrane potential and action potential threshold? A) The resting potential would hyperpolarize and the action potential threshold would not change. B) The resting potential would depolarize and the action potential threshold would decrease. C) The resting potential would depolarize and the action potential threshold would not change. D) The resting potential would hyperpolarize and the action potential threshold would increase.

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section: Chapter Questions

Problem 4TAHL: Assume presynaptic excitatory neuron A terminates on a postsynaptic cell near the axon hillock and...

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Assume presynaptic excitatory neuron A terminates on a postsynaptic cell near the axon hillock and presynaptic excitatory neuron B terminates on the same postsynaptic cell on a dendrite located on the side of the cell body opposite the axon hillock. Explain why rapid firing of presynaptic neuron A could bring the postsynaptic neuron to threshold through temporal summation, thus initiating an action potential, whereas firing of presynaptic neuron B at the same frequency and the same magnitude of EPSPs may not bring the postsynaptic neuron to threshold.
Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)
Match each type of membrane potential (resting, threshold, graded, or action) to its definition: a) The membrane potential at which voltage gated sodium channels open. b) The membrane potential that triggers the action potential. c) Change in membrane potential that may or may not reach threshold and that may be depolarizing or hyperpolarizing. d) Rapid, strong depolarization followed by immediate repolarization. This potential is self-renewing if the right ion channels are nearby.
Please answer both 1) What is responsible for returning the cell to its normal resting membrane potential following the absolute refractory period? a) K+ leak channels b) the Na+/K+ pump c) activation of voltage-gated Na+ channels d) a ligand binding to a ligand-gated Na+ channel 2) What property of an action potential allows it to propagate? a) the rapid period of depolarization b) the rapid period of repolarization c) the brief period of hyperpolarization d) the fact that the peak is 85 mV above threshold
The resting membrane potential…A) Can be approximated using the Nernst equation.B) Is established by a difference in charges across the cell membrane, with the inside more positive than the outside.C) Has no influence on the driving force for flow of a particular ion across the cell membrane.D) Is more dependent on the passive flow of potassium vs. sodium ions through leak channels across the cell membrane.E) Stays the same during an action potential.
Suppose you inactivated a neuron’s Na/K exchange pumps (the active transporters), then immediately stimulated the neuron. i) Would the action potential fail to occur or be different from usual? Briefly explain. ii) Would repolarization fail to occur or be different from usual? Explain briefly. iii) Would the cell’s ability to respond to a second stimulus be changed? Explain briefly.
1.A poison causes a drastic rise inE value with stimulation of the membrane.Thereafter membrane is slow to return towards resting membrane potential and levels off several millivolts above the threshold potential. This poison has likely affect which feature of the membrane? a) voltage gated na+ channels. b) voltage gated K+ channels. c) Na+/K+ Atp pump 2. All cell membrane demonstrate action potential if stimulated enough? True/False. 3. how many peaks are there in a compound action potential? a)2. b)4 c)6 d)8 4. Increasing the ionic concentration in the salt bridge results in E value increase to a point after which it plateeus. This is evidence brownian movement at work in the ionic solution that is keeping from energy flowing through the bridge with the fidelity that is seen in the metal bridge? True/ False 5. All cell membrane demonstrate action potential if stimulated enough? True or False.
Nerve membrane hyperpolarization after an action potential a)Is the movement of membrane potential voltage below normal resting potential voltage. b) This Is mostly due to the slow-closing of K+ channels. c)Makes it more difficult to evoke another action potential. d) This Is mostly due to the slow-closing of Na+ channels.
When a neuron fires an action potential, closing of the voltage-gated Na+ channels helps to bring an end to _________. A) the depolarizing phase of the action potential B) the repolarizing phase of the action potential C) graded potential changes D) the resting potential E) vesicle fusion at the synapse
Fluorescent FM dyes partition reversibly into biological membranes without penetrating through them. Suppose that you have neurons cultured in a dish, and you incubate them with an FM dye for a period of time before washing the cells with excess medium to remove the dye. a) You find that if you stimulate the neurons to trigger action potentials during incubation with the dye, the synaptic regions of the neurons remain fluorescent after the wash. Propose an explanation for this effect. b) After you have generated fluorescent synaptic regions by this procedure, suppose that you trigger further action potentials while continuing to wash with excess medium. Would you expect the synaptic regions to lose fluorescence? Explain.
The extracellular sodium [Na+]0 is reduced in the saline bath. Following another current injection in a neuron, the membrane potential changes were recorded. a) Why has the membrane potential changed following the Na+ reduction? b) Why has the current injection produced no action potentials? c) How might you experimentally rescue action potential generation?
What force(s) act(s) to move potassium ions from the inside of the cell to the outside when a neuron is about to enter the hyperpolarization phase of an action potential? O a) The sodium-potassium pump Ob) The electrical (electrostatic) gradient only Oc) The concentration (chemical) gradient only d) Both the concentration (chemical) gradient and the electrical (electrostatic) gradient