Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) Suppose that a presynaptic neuron releases acetylcholine from its axon terminals, which then binds to acetylcholine receptors on the postsynaptic cell, and this causes an EPSP to occur in the postsynaptic cell. Which of the following statements CANNOT be true?
A. The postsynaptic acetylcholine receptors are ligand-gated ion channels that are
opened when they bind acetylcholine
B. Sodium enters the cell through the acetylcholine receptor channel
C. Acetylcholine functions as an excitatory neurotransmitter at this synapse
**D. The acetylcholine receptor channel is permeable only to chloride
E. The postsynaptic membrane becomes depolarized from rest when acetylcholine
binds to the receptor
____2) Which of the following ions is a monovalent anion?
A. Calcium
B. Sodium
***C. Chloride
D. Potassium
E. Magnesium
3) Many sensory neurons in the eye, nose, and ear are bipolar neurons. By contrast, neurons in the Dorsal Root Ganglion are ****monopolar (or unipolar) neurons.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) Which of the following statements is NOT TRUE when a neuron is at its resting membrane potential?
A. The electrical gradient pushes sodium towards the inside of the cell
B. The chemical gradient pushes sodium towards the inside of the cell
C. The electrical gradient pushes potassium towards the inside of the cell
**D. The chemical gradient pushes potassium towards the inside of the cell
E. Sodium ions are not in electrochemical equilibrium
____2) Which if the following is the main excitatory neurotransmitter in the central nervous system?
A. GABA
B. glycine
C. Dopamine
***D. Glutamate
E. Serotonin
3) A pore in the cell membrane that is always open and never closed (allowing ions to pass through the membrane at all times) is called a ***leak channel.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) An unknown ion X has a reversal potential of +100 mV. When a neuron is at resting potential, both the electrical and chemical gradients push X toward the inside of the cell. Which of the following statements about X cannot be true?
A. The membrane is not permeable to X at rest
B. The concentration of X is greater outside the cell than inside the cell
***C. X is an anion
D. X is not at equilibrium when the neuron is at rest
E. X is divalent
____2) A pore in the membrane that opens only when the membrane potential rises above -55 mV is an example of a:
A. Leak channel
****B. Voltage-gated ion channel
C. Ligand-gated ion channel
D. ATPase pump
E. Modulatory neurotransmitter
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) There are two different kinds of cells in the brain: 10% of the cells are neurons, and the other 90% are ***glia (or glial cells).
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) In class we have learned that when neurotransmitters are released from a presynaptic cell, they bind to receptors on the postsynaptic cell. We have also learned that there are different kinds of neurotransmitters: excitatory, inhibitory, and modulatory. Based on what you know about the neurotransmitter GABA, which of the following membrane proteins would GABA be most likely to bind to?
A. a ligand-gated sodium channel (reversal potential = +60 mV)
B. a voltage-gated sodium channel (reversal potential = +60 mV)
C. a voltage-gated potassium channel (reversal potential = -80 mV)
D. a leak potassium channel (reversal potential = -80 mV)
****E. a ligand-gated chloride channel (reversal potential = -90 mV)
____2) Which of the following ions is divalent?
A. Sodium
***B. Calcium
C. Potassium
D. Chloride
E. None of the above
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) A person is suffering from a disease in which their brain’s oligodendrocytes are dying. This person’s disease is called ****multiple sclerosis.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) Which of the following types of ion channels is permeable to the same ion as the delayed rectifier channel?
A. The voltage-gated ion channels that trigger the action potential
B. Ligand-gated ion channels that cause EPSPs when they are opened
****C. Leak channels
D. Ligand-gated ion channels that are opened by glutamate
E. A channel that drives the membrane toward an equilibrium potential of +120 mV
whenever it is opened
____2) When a neuron is at rest, which if the following ions has a higher concentration inside of the cell than outside of the cell?
A. Sodium
****B. Potassium
C. Calcium
D. Chloride
E. All of the above are more highly concentrated outside of the cell
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) There are three ways an action potential can propagate through an axon: passive
conductance, active conductance, and **saltatory** conductance.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) An action potential would travel fastest in which type of axon? (Note: one micron equals one milliionth of a meter)
****A. A myelinated axon that is 5 microns in diameter (that is, 5 microns thick)
B. An unmyelinated axon that is 5 microns in diameter
C. An unmyelinated axon that is 10 microns in diameter
D. A myelinated axon that is 2 microns in diameter
E. An unmyelinated axon that is 2 microns in diameter
____2) Which of the following factors does NOT contribute to ending the action potential?
A. Sodium is pumped out of the cell by the Na,K ATPase
B. Voltage-gated sodium channels become inactivated
***C. Leak channels re-open after temporarily closing during the action potential
D. Voltage-gated potassium channels are opened by the action potential
E. All of the above contribute to ending the action potential
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) A pore in the cell membrane that opens when a chemical binds to it and allows ions to cross the membrane is called a **ligand-gated ion channel.
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) Which of the following statements is true ONLY when a neuron is at the equilibrium potential for potassium, but not at any other time?
A. Potassium leak channels are open
**B. The electrical and chemical gradients push equally on potassium, but in opposite directions
C. The electrical gradient pushes potassium towards the inside of the cell
D. The chemical gradient pushes potassium towards the inside of the cell
E. The chemical gradient pushes potassium towards the outside of the cell
____2) When one presynaptic neuron fires an action potential, it causes a small EPSP in the postsynaptic cell. When two different presynaptic neurons fire action potentials simultaneously, a larger EPSP occurs in the postsynaptic cell. This is an example of:
A. Saltatory Conductance
B. Passive Conductance
**C. Spatial Summation
D. Active Conductance
E. Temporal Summation
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) The outside of a neuron is bathed in cerebrospinal fluid, and the inside of a neuron is filled with ***cytoplasm.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) Assume that two different neurons, A and B, both have a ligand-gated ion channel in their membranes that is ONLY permeable to potassium and no other ions. In neuron A, the membrane is briefly depolarized from rest when the ligand binds to the channel. In neuron B, the membrane is briefly hyperpolarized from rest when the ligand binds to the channel. Which of the following statements MUST be true?
A. The resting potential of neuron A is -70 mV
B. The resting potential of neuron B is -90 mV
***C. The resting potentials of neurons A and B are different
D. Neuron B contains leak chloride channels
E. Neuron A contains no voltage-gated sodium channels
____2) In the peripheral nervous system, the cells that provide the myelin sheath around axons are called ___________, and each of these cells provides a sheath for ________ axon.
***A. Schwann cells; one
B. Schwann cells, more than one
C. Oligodendrocytes; one
D. Oligodenrocytes; more than one
E. Glial cells; more than one
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) The sodium ***equilibrium (or reversal or Nernst)*** potential is the membrane voltage that a neuron will have when the membrane is permeable only to sodium and no other ions.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) Which of the following statements is ONLY TRUE when a neuron is at the equilibrium potential for sodium, and not at any other time?
A. The electrical gradient pushes sodium towards the inside of the cell
B. The chemical gradient pushes sodium towards the inside of the cell
**C. On average, an equal number of sodium ions flows into and out of the cell
D. No sodium ions at all flow in or out of the cell
E. The electrical and chemical gradients push sodium in opposite directions
____2) Which of the following neurotransmitters is the main inhibitory neurotransmitter in the central nervous system?
A. Dopamine
B. Acetylcholine
C. Serotonin
**D. GABA
E. Glutamate
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) An atom which contains two more protons than electrons is called a **divalent** cation.
Multiple Choice (choose the single best answer and write it in the blank).
(2 points each, 4 points total)
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) If a person was poisoned with picrotoxin (which blocks delayed rectifier channels), what would happen to their neurons (choose only ONE best answer)?
A. Neurotransmitters would no longer bind to ligand-gated ion channels
B. Action potentials would no longer occur when the membrane is depolarized from
the resting potential
C. The sodium-potassium ATPase pump would cease to function
**D. The membrane would not properly repolarize after an action potential
E. Spatial summation of EPSPs would no longer occur, but temporal summation of
EPSPs would remain unaffected
____2) A neuron’s membrane is permeable only to one ion and no others. The membrane potential of this neuron is +60 mV. Which ion is the membrane permeable to?
**A. Sodium
B. Calcium
C. Potassium
D. Chloride
E. Magnesium
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) A positively charged ion is called a(n) **cation.
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) If a person was poisoned with tetrodotoxin, what would happen to their neurons (choose only ONE best answer)?
A. Neurotransmitters would no longer bind to ligand-gated ion channels
**B. Voltage-gated sodium channels would no longer open
C. The sodium-potassium ATPase pump would cease to function
D. The membrane would not properly repolarize after an action potential
E. Spatial summation of EPSPs would no longer occur, but temporal summation of
EPSPs would remain unaffected
____2) Neurons in the _______________ are myelinated by Schwann cells.
A. Neocortex
B. Amygdala
C. Subthalamic nucleus
D. Hypothalamus
**E. Dorsal Root Ganglion
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) There are two forces that act to push ions back and forth across the membrane of a neuron: an electrical force and a **chemical** force.
Use the following information if needed to answer the questions:
Ion equilibrium potentials: EK = -80 mV; ENa = +60 mV; ECl = -90 mV; ECa = +120 mV
Resting membrane potential = -75 mV
____1) A glutamatergic neuron is firing at a rate of 4 Hz. This presynaptic neuron releases glutamate onto a postsynaptic neuron, which causes EPSPs to occur in the postsynaptic neuron. However, these EPSPs do not elicit action potentials from the postsynaptic neuron. The presynaptic neuron increases its rate to 12 Hz, and now the postsynaptic neuron starts firing action potentials. Which of the following explanations best describes why the postsynaptic neuron did not start firing action potentials until the presynaptic neuron increased its firing rate?
A. The spike threshold in the postsynaptic cell was too high when the presynaptic
cell was firing slowly
B. Glutamate could not bind to postsynaptic receptors when the presynaptic cell
was firing slowly
C. Spatial summation of EPSPs did not occur when the presynaptic cell was firing
slowly
**D. Temporal summation of EPSPs occurred only after the presynaptic cell increased its firing rate
E. The presynaptic cell releases GABA when it is firing slowly, but not when it is
firing quickly
____2) Which part of a neuron contains synaptic vesicles?
A. Soma
B. Dendrite
**C. Axon terminal
D. Active Zone
E. Nucleus
Fill-in-the-blank (write the correct word or phrase in the blank).
(3 points each, 3 points total)
3) A sodium channel can be in one of three states: closed, open, or **inactivated
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