Question 1

The difference in electrical charge between two points:
A)is called the potential difference between those points.
B)is called the diffusion potential between those points.
C) is called the the current,and is expressed in the units of millimoles.
D)is the same for all ions.

Accepted Answer

The difference in electrical charge between two points is called the potential difference between those points. It is an important concept in physics and is commonly used in electrical engineering and electrophysiology.

Question 2

Which is TRUE about typical,resting neurons?
A)The plasma membrane is most permeable to sodium ions.
B)The concentration of sodium ion is greater inside the cell than outside.
C) The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions.
D)The plasma membrane is completely impermeable to sodium ions.
E)The plasma membrane is completely impermeable to potassium ions.

Accepted Answer

Resting neurons typically have a resting membrane potential that is maintained by the selective permeability of the plasma membrane to different ions. The plasma membrane is more permeable to potassium ions than sodium ions, which is why choice C is correct. The concentration of sodium ion is higher outside the cell than inside, making choice B incorrect. The plasma membrane is not completely impermeable to either sodium or potassium ions, making choices D and E incorrect. Choice A is incorrect because the plasma membrane is not most permeable to sodium ions, even though it is somewhat permeable to this ion.

Question 3

Which is FALSE about neurons?
A)A given neuron can be either a presynaptic neuron or a postsynaptic neuron.
B)An individual neuron can receive information from multiple other neurons.
C)An individual neuron can transmit information to multiple other neurons.
D)A neuron can simultaneously release more than one type of neurotransmitter.
E)A neuron receives information on its axons and delivers it to other neurons through its dendrites.

Accepted Answer

Neurons receive information on their dendrites and transmit it through their axons.

Question 4

The diffusion potential due to the concentration gradient for Na⁺ across a nerve cell membrane: A)favors its movement into the cell at the resting membrane potential. B)favors its movement out of the cell at the resting membrane potential. C)is equal and opposite to the electrical potential acting on Na⁺ at the resting membrane potential. D)Is in the same direction as the diffusion potential due to the concentration gradient for K⁺. E)favors movement of Na⁺ in the opposite direction as the electrical potential acting on Na⁺ at the resting membrane potential.

Accepted Answer

The answer of The diffusion potential due to the concentration...

Question 5

Which is NOT an example of a graded potential?
A)a receptor potential in a sensory receptor cell
B)a depolarizing excitatory postsynaptic potential (EPSP)
C)a hyperpolarizing inhibitory postsynaptic potential (IPSP)
D)a depolarizing pacemaker potential
E)a depolarizing action potential

Accepted Answer

Graded potentials are small changes in membrane potential that can either depolarize (EPSP) or hyperpolarize (IPSP) a neuron, but they do not reach the threshold for an action potential. Action potentials, on the other hand, are a type of all-or-none electrical signal that are triggered once the membrane potential reaches a certain threshold. Therefore, a depolarizing action potential is not an example of a graded potential.

Question 6

An action potential in a neuronal membrane differs from a graded potential in that: A)an action potential requires the opening of Ca²⁺ channels,whereas a graded potential does not. B)an action potential is propagated without decrement,whereas a graded potential decrements with distance. C)an action potential has a threshold,whereas a graded potential is an all-or-none phenomenon. D)movement of Na⁺ and K⁺ across cell membranes mediate action potentials,while graded potentials do not involve movement of Na⁺ and K⁺. E)action potentials vary in size with the size of a stimulus,while graded potentials do not.

Accepted Answer

The answer of An action potential in a neuronal membrane...

Question 7

The membrane potential of most neurons at rest is:
A)equal to the equilibrium potential for potassium.
B)equal to the equilibrium potential for sodium.
C) slightly more negative than the equilibrium potential of potassium ion.
D) more positive than the equilibrium potential for potassium.
E) more positive than the equilibrium potential for sodium.

Accepted Answer

The answer of The membrane potential of most neurons at...

Question 8

Which of the following is not true of glial cells?
A)They form the myelin for axons.
B)Neurons outnumber glial cells 10 to 1 in the nervous system.
C)They deliver fuel molecules to neurons and remove the waste products of metabolism.
D)They are important for the growth and development of the nervous system.
E)They regulate the composition of the extracellular fluid in the CNS.

Accepted Answer

This statement is not true as the opposite is actually true. Glial cells outnumber neurons 10 to 1 in the nervous system.

Question 9

A threshold stimulus applied to an excitable membrane is one that is just sufficient to:
A)trigger an excitatory postsynaptic potential.
B)cause a change in membrane potential.
C)trigger an action potential.
D)be conducted to the axon hillock.
E)depolarize a dendrite.

Accepted Answer

A threshold stimulus is the minimal level of stimulation required to trigger an action potential in an excitable membrane. It is the point at which the membrane potential reaches the threshold voltage and rapidly depolarizes to generate an action potential.

Question 10

Which of the following is not true about axon transport?
A)It refers to the passage of materials from the cell body of a neuron to the axon terminals.
B)It refers to the passage of materials from axon terminals to the cell body of a neuron.
C)It refers to the transport of materials from the inside to the outside across the axonal membrane.
D)It is especially important for maintaining the integrity of neurons with long axons.

Accepted Answer

Axon transport refers to the movement of materials from the cell body of a neuron to the axon terminals or vice versa. It does not refer to the transport of materials across the axonal membrane as this is a function of ion channels and pumps.

Question 11

Which is TRUE about the Na⁺,K⁺ ATPase pump in neurons? A)It generates a small electrical potential such that the inside is made negative with respect to the outside. B)It maintains a concentration gradient for K⁺ such that diffusion forces favor movement of K⁺ into the cell. C)It maintains an electrical gradient at the equilibrium potential of K⁺. D)It transports equal numbers of sodium and potassium ions with each pump cycle. E)It pumps 3 Na⁺ ions into the cell for every 2 K⁺ ions it pumps out.

Accepted Answer

The answer of Which is TRUE about the Na⁺,K⁺ ATPase...

Question 12

Which of the following is/are functions of the human nervous system?
A) receiving,storing,and processing information on the internal and external environments
B)bringing about changes in physiology and/or behavior to ensure optimal functions of homeostatic mechanisms
C)secretion of hormones
D)coordination of movement
E)All of the choices are correct.

Accepted Answer

All of the choices listed are functions of the human nervous system. The nervous system receives, stores, and processes information on both internal and external environments, and also brings about changes in physiology and behavior to maintain homeostasis. In addition, the nervous system coordinates movement and mediates the secretion of hormones.

Question 13

Which of these would occur if the concentration of ATP were depleted in a typical nerve cell? A)Resting membrane potential would become more negative. B)Resting membrane potential would become less negative. C)The concentration gradient for Na⁺ would remain the same. D)The resting membrane potential would eventually become positive inside with respect to outside. E)There would be no change in the resting membrane potential.

Accepted Answer

ATP is required for the function of the sodium-potassium pump which maintains the concentration gradient of Na+ and K+. Without sufficient ATP, the pump would not function properly, leading to a higher concentration of sodium ions inside the cell and lower concentration of potassium ions. This would lead to a less negative resting membrane potential in the nerve cell.

Question 14

Which of the following statements concerning the permeability of a typical neuron membrane at rest is true? A)The permeability to Na⁺ is much greater than the permeability to K⁺. B) All of the K⁺ channels in the membrane are open. C)The voltage-gated Na⁺ channels are in the inactivated state. D)Most of the voltage-gated Na⁺ channels are in the closed state. E)There is equal permeability to Na⁺ and K⁺.

Accepted Answer

At rest, most voltage-gated Na+ channels are in the closed state, and some may be in the inactivated state. The permeability to K+ is higher than that of Na+ at rest, but not all K+ channels are necessarily open. Therefore, option D is the correct choice.

Question 15

Which is not true of myelin?
A)It is a fatty membranous sheath.
B)It is formed by glial cells.
C)It influences the velocity of conduction of an electrical signal down an axon.
D) It covers all parts of the neuron,including the axon,cell body,and dendrites.

Accepted Answer

Myelin only covers the axon of a neuron, not the cell body or dendrites.

Question 16

Which is TRUE about the resting membrane potential?
A)It requires very few ions to be distributed unevenly.
B)It has the same value in all cells.
C)It is oriented so that the cell's interior is positive with respect to the extracellular fluid.
D)Only nerve and muscle cells have a potential difference across the membrane at rest.
E)It is not altered by changing concentration gradients of permeating ions.

Accepted Answer

The resting membrane potential is established with relatively few ions needing to be distributed unevenly across the cell membrane, creating a voltage difference. This is due to the cell membrane's selective permeability to certain ions and the action of ion pumps.

Question 17

The equilibrium potential of K⁺ ions in nerve cells is about -90 mV.The membrane potential of typical nerve cells at rest is -70 mV.Therefore A)Increasing the permeability of a resting neuronal membrane to K⁺ will make the membrane potential more negative inside with respect to outside. B)In resting neurons,there is a net diffusion of K⁺ into the cell. C) changing the resting membrane potential of a neuron to -80 mV would increase K⁺ diffusion rate out of the cell. D) potassium is the only permanent ion at rest. E) there must be another permanent ion with an equilibrium potential more negative than -90 mV.

Accepted Answer

The equilibrium potential of K⁺ ions in nerve cells is more negative than the resting membrane potential of typical nerve cells. Therefore, increasing the permeability of a resting neuronal membrane to K⁺ will make the membrane potential more negative inside with respect to outside. This will lead to hyperpolarization of the cell. Answer: B At resting potential, the membrane is more permeable to potassium which causes the potassium ions to diffuse out of the cell. This results in a net diffusion of potassium ions out of the cell, which contributes to the negative resting potential. Answer: C Increasing the negative membrane potential will increase the electrical gradient, which will decrease the diffusion rate of positively charged ions out of the cell. Therefore, changing the resting membrane potential of a neuron to -80 mV would decrease K⁺ diffusion rate out of the cell. Answer: E There are other ions, such as chloride ions, that have equilibrium potentials more negative than -90 mV. Chloride ions can contribute to the resting potential of the membrane, although they are not as important as potassium ions. Answers A, B, C, and E are all valid choices.

Question 18

According to the equation expressed as Ohm's law,which of these would cause the greatest increase in current?
A)doubling both voltage and resistance
B)reducing both voltage and resistance by half
C)doubling voltage and reducing resistance by half
D)reducing voltage by half and doubling resistance
E)quadrupling both voltage and resistance

Accepted Answer

Ohm's law states that current is directly proportional to voltage and inversely proportional to resistance. Therefore, increasing voltage and decreasing resistance will result in the greatest increase in current. Doubling voltage and reducing resistance by half is the only option that fits this criteria.

Question 19

Which would result from an increase in the extracellular concentration of K⁺ above normal? A)depolarization of resting nerve cells B)hyperpolarization of resting nerve cells C)The potassium equilibrium potential of nerve cells would become more negative. D)The sodium equilibrium potential would become less positive.

Accepted Answer

The answer of Which would result from an increase in...

Question 20

Which is FALSE about the equilibrium potential of a given ion across a membrane?
A)It is a function of the concentration of that ion on both sides of the membrane.
B)It is the potential at which there is no net movement of that ion across the membrane.
C)It is the potential difference across the membrane at which an electric force favoring movement of the ion in one direction is equal in magnitude and opposite in direction to the diffusion force provided by the concentration difference of the ion across the membrane.
D)A permeable ion will move in the direction that will tend to bring the membrane potential toward that ion's equilibrium potential.
E)An anion that is in higher concentration inside the cell than outside the cell will have a negative eqilibrium potential.

Accepted Answer

An anion that is in higher concentration inside the cell than outside the cell will have a positive equilibrium potential. This is because the negative charge inside the cell will attract positive ions and repel negative ions, causing an electrical force that opposes the movement of negatively charged ions into the cell. Therefore, for an anion to reach equilibrium, the membrane potential would have to become more positive, resulting in a positive equilibrium potential.

Quiz 6: Neuronal Signaling and the Structure of the Nervous System

The difference in electrical charge between two points:

Which is TRUE about typical,resting neurons?

Which is FALSE about neurons?

The diffusion potential due to the concentration gradient for Na+ across a nerve cell membrane:

Which is NOT an example of a graded potential?

An action potential in a neuronal membrane differs from a graded potential in that:

The membrane potential of most neurons at rest is:

Which of the following is not true of glial cells?

A threshold stimulus applied to an excitable membrane is one that is just sufficient to:

Which of the following is not true about axon transport?

Which is TRUE about the Na+,K+ ATPase pump in neurons?

Which of the following is/are functions of the human nervous system?

Which of these would occur if the concentration of ATP were depleted in a typical nerve cell?

Which of the following statements concerning the permeability of a typical neuron membrane at rest is true?

Which is not true of myelin?

Which is TRUE about the resting membrane potential?

The equilibrium potential of K+ ions in nerve cells is about -90 mV.The membrane potential of typical nerve cells at rest is -70 mV.Therefore

According to the equation expressed as Ohm's law,which of these would cause the greatest increase in current?

Which would result from an increase in the extracellular concentration of K+ above normal?

Which is FALSE about the equilibrium potential of a given ion across a membrane?

The diffusion potential due to the concentration gradient for Na⁺ across a nerve cell membrane:

Which is TRUE about the Na⁺,K⁺ ATPase pump in neurons?

The equilibrium potential of K⁺ ions in nerve cells is about -90 mV.The membrane potential of typical nerve cells at rest is -70 mV.Therefore

Which would result from an increase in the extracellular concentration of K⁺ above normal?