Bio 121 Nerve Quiz
At which of the following membrane potentials would you expect the voltage-gated sodium channels to close and the voltage-gated potassium channels to open? +30mV -60mV 0mV -90mV
+30mV
The sodium-potassium ion exchange pump a) is not involved in producing the resting membrane potential. b) transports sodium ions into the cell during depolarization. c) transports potassium ions out of the cell during repolarization. d) moves sodium and potassium opposite to the direction of their electrochemical gradients. e) depends on a hydrogen gradient for energy
moves sodium and potassium opposite to the direction of their electrochemical gradients
threshold
"just sufficient" depolarization
Depolarization of a neuron cell membrane will shift the membrane potential toward __________. -90 mV -70 mV 0 mV -85 mV
0 mV
In a typical neuron at rest, the Na-K ion exchange pump transports a) 1 sodium ion out for 2 potassium ions in. b) 2 sodium ions out for 1 potassium ion in. c) 3 sodium ions in for 3 potassium ions out. d) 3 sodium ions out for 2 potassium ions in
3 sodium ions out for 2 potassium ions in
What happens when a barrier prevents the movement of opposite charges toward one another? An action potential occurs. A graded potential is produced. A potential difference exists. A current is produced.
A potential difference exists
The________ open or close in response to binding specific molecules. a) Leak channels b) Mechanically-gated channels c) Chemically gated channels d) Voltage-gated channels
Chemically gated channels
The ________ line the brain ventricles and spinal canal. a) Astrocytes b) Satellite cells c) Oligodendrocytes d) Microglia e) Ependymal cells
Ependymal cells
What type of neuroglial cell participates in the production and circulation of cerebrospinal fluid? Astrocytes Ependymal cells Microglia Oligodendrocytes
Ependymal cells
Increasing the intensity of a stimulus applied to a receptor will increase the amplitude of action potentials, assuming constant conditions. True False
False
The ___________ are the most numerous type of neuron in the CNS. a) Sensory neurons b) Motor neurons c) Unipolar neurons d) Bipolar neurons e) Interneurons
Interneurons
Which of the following is true for the sodium-potassium (Na+/K+) exchange pump? a) It helps maintain the resting membrane potential by exchanging three intracellular sodium ions for two extracellular potassium ions. b) It helps maintain the resting membrane potential by exchanging three intracellular potassium ions for two extracellular sodium ions. c) It helps maintain the resting membrane potential by exchanging two intracellular potassium ions for three extracellular sodium ions. d) It helps maintain the resting membrane potential by exchanging two intracellular sodium ions for three extracellular potassium ions.
It helps maintain the resting membrane potential by exchanging three intracellular sodium ions for two extracellular potassium ions.
The ________ channels open or close in response to physical distortion of the membrane surface. a) Voltage-gated b) Chemically gated c) Leak d) Mechanically gated e) Leak
Mechanically gated
What type of gated channel opens or closes in response to distortion of the membrane? Chemically gated channel Mechanically gated channel Leak channel Voltage-gated channel
Mechanically gated channel
Which type of neuroglial cell functions in the central nervous system to engulf cellular debris, waste products, and pathogens? Ependymal cells Microglia Oligodendrocytes Astrocytes
Microglia
Which cells produce myelin for neurons in the CNS? Oligodendrocytes Schwann cells Astrocytes Ependymal cells
Oligodendrocytes
Why do nerve impulses travel only in one direction? The impulse direction is controlled by the central nervous system. Depolarization cannot move through the neuron cell body. Only the axon side of a neuron can release chemical transmitters. The orientation of the myelin sheath determines the direction of the impulse.
Only the axon side of a neuron can release chemical transmitters
Which of the following is NOT a characteristic of a graded potential? Can be depolorizing or hyperpolarizing Passively spreads outward in all directions from the site of stimulation with a decrease in intensity Propagates along the entire membrane without a decrease in strength Amount of stimulation depends on the intensity of the stimulus
Propagates along the entire membrane without a decrease in strength
What type of neuroglial cell myelinates axons in the peripheral nervous system? Schwann cells Astrocytes Satellite cells Microglia
Schwann cells
Which of the following is a function of neuroglia? a) regulate the composition of interstitial fluid b) provide a supportive framework c) produce cerebrospinal fluid d) act as phagocytes e) all of the above
all of the above
Which of the following statements about the sodium-potassium pump is correct? a) The activity of the sodium-potassium pump is needed after every action potential in order to maintain the resting potential. b) The sodium-potassium pump brings sodium into and forces potassium out of a neuron during depolarization. c) The sodium-potassium pump is a leak channel that allows passive movement of sodium and potassium ions down the concentration gradient. d) The sodium-potassium pump requires ATP to pump sodium and potassium ions from higher to lower concentrations along their concentration gradients.
The activity of the sodium-potassium pump is needed after every action potential in order to maintain the resting potential
Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? a) Neurons would depolarize more rapidly. b) Action potentials would lack a repolarization phase. c) The absolute refractory period would be shorter than normal. d) The axon would be unable to generate action potentials. e) None, because the chemically gated sodium channels would still function.
The axon would be unable to generate action potentials
What forces are involved in creating the electrochemical gradient for potassium? The chemical gradient keeps potassium in the cell, while the electrical gradient moves potassium out of the cell. Both the electrical and chemical gradients move potassium into the cell. Both the electrical and chemical gradients move potassium out of the cell. The chemical gradient moves potassium out of the cell, while the electrical gradient keeps potassium in the cell.
The chemical gradient moves potassium out of the cell, while the electrical gradient keeps potassium in the cell
If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential? a) The inside of the membrane will become more positive. b The inside of the membrane will become more negative c) There will be almost no effect on transmembrane potential. d) The membrane will become depolarized. e) none of the above
The inside of the membrane will become more negative
Which of the following statements about the action potential is false? a) The rapid depolarization phase is caused by the entry of potassium ions b) During the repolarization phase, sodium channels are closed and potassium channels are open. c) During the depolarization phase, membrane potential becomes positive. d) None of these statements is false, all are true.
The rapid depolarization phase is caused by the entry of potassium ions
The function of a receptor is to transduce, or transform, environmental stimuli into receptor potentials which, in turn, initiate action potentials. True False
True
Temporal summation occurs when: a presynaptic neuron is inhibited by neuromodulators many presynaptic neurons inhibit one postsynaptic neuron a single presynaptic neuron fires a rapid series of many signals at one postsynaptic neuron many presynaptic neurons transmit signals at the same time to one postsynaptic neuron
a single presynaptic neuron fires a rapid series of many signals at one postsynaptic neuron
The period following an action potential during which another action potential cannot be initiated at the same location regardless of the strength of the stimulus is the: resting potential relative refractory period absolute refractory period stable period
absolute refractory period
Cholinergic synapses release the neurotransmitter a) norepinephrine. b) adrenalin. c) serotonin. d) acetylcholine
acetylcholine
neurotransmitter
acetylcholine
all-or-none event
action potential
A typical nerve cell: conducts an impulse from one part of the nervous system to another consists of a cell body, dendrites, and axon releases a chemical transmitter substance from the axon fiber all of the above
all of the above
In the process of continuous action potential propagation, a) the action potential is triggered by graded depolarization of the initial segment. b) at threshold, sodium channels begin to open rapidly. c) local currents depolarize the region just adjacent to the active zone. d) all of the above e) none of the above
all of the above
Ions can move across the plasma membrane in which of the following ways? a) through voltage-gated channels as in the action potential b) through passive or leak channels c) by ATP-dependent ion pumps like the sodium-potassium exchange pump d) through chemically-gated channels as in neuromuscular transmission e) all of the above
all of the above
The all-or-none principle states that a) all stimuli will produce identical action potentials. b) all stimuli great enough to bring the membrane to threshold will produce identical action potentials. c) the greater the magnitude of the stimuli, the greater the magnitude of the action potential. d) only sensory stimuli can activate action potentials. e) only motor stimuli can activate action potentials.
all stimuli great enough to bring the membrane to threshold will produce identical action potentials.
IPSPs (inhibitory postsynaptic potentials) a) are graded depolarizations. b) are graded hyperpolarizations c) increase membrane permeability to sodium ions. d) block the efflux of potassium ions. e) block the efflux of calcium ions.
are graded hyperpolarizations
At the synapse, what opens Ca++ channels in the axon of the presynaptic neuron? hyperpolarization arrival of an action potential neurotransmitters binding to the presynaptic membrane neurotransmitter synthesis
arrival of an action potential
The largest and most numerous neuroglia in the CNS that absorb and recycle neurotransmitters are the a) astrocytes b) ependymal cells. c) microglia. d) oligodendrocytes. e) none of the above
astrocytes
The neuroglia cells that help supply neurons with nutrients are the __________. microglia cells astrocytes Schwann cells ependymal cells
astrocytes
single long process extending from neuron
axon
The site in the neuron where EPSPs and IPSPs are integrated is the a) synaptic knob. b) electrical synapse. c) axon hillock. d) dendritic membrane.
axon hillock
If Cl- ions were to rush into a neuron, its membrane potential would __________. become more positive (undergo depolarization) become more negative (undergo hyperpolarization) undergo no change be repolarized
become more negative (undergo hyperpolarization)
If the permeability of a resting axon to sodium ion increases, a) the membrane will depolarize. b) the membrane will hyperpolarize. c) inward movement of sodium ions will increase. d) outward movement of sodium ions will decrease. e) both the inward movement of sodium ions will increase and the membrane will depolarize
both the inward movement of sodium ions will increase and the membrane will depolarize
In a neuron, an action potential is propagated along the axon: by depolarization of successive regions of membrane as a result of local current flow towards the soma of the presynaptic neuron by chemical transmitters directly by the activities of the sodium-potassium pump
by depolarization of successive regions of membrane as a result of local current flow
The ion that triggers the release of acetylcholine into the synaptic cleft is a) sodium. b) potassium. c) calcium. d) chloride. e) magnesium
calcium
Efferent neurons: carry sensory information control only involuntary movements carry motor signals carry action potentials from muscles or glands to the CNS
carry motor signals
The resting membrane potential of a nerve cell is: not dependent on the Na - K pump for its maintenance about -5mV inside negative to outside caused by unequal distribution of Na+ and K+ on each side of the cell membrane typically about +50 mV inside positive
caused by unequal distribution of Na+ and K+ on each side of the cell membrane
Satellite cells are __________. a) cells that surround neuron cell bodies in ganglia and regulate interstitial fluid around the neuron b) cells that produce cerebrospinal fluid c) phagocytic cells that move through the nervous system and remove unwanted substances d) also called neurolemmocytes and produce myelin that surrounds peripheral axons
cells that surround neuron cell bodies in ganglia and regulate interstitial fluid around the neuron
Which type of active channels in the plasma membrane open or close when they bind certain chemicals, such as neurotransmitters? Chemically gated channels Mechanically gated channels Voltage-gated channels Passive channels
chemically gated channels
Branches that may occur along an axon are called a) synapses. b) synaptic knobs. c) collaterals d) hillocks
collaterals
Functions of astrocytes include all of the following, except a) maintaining the blood-brain barrier. b) conducting action potentials c) forming a three-dimensional framework for the CNS. d) responding to neural tissue damage.
conducting action potentials
receives signal from axon
dendrite
Wallerian degeneration __________. describes the breakdown of astrocytes distal to the site of an injury describes the breakdown of Schwann cells distal to the site of an injury describes the breakdown on the soma distal to the site of an injury describes the breakdown on an axon distal to the site of injury
describes the breakdown on an axon distal to the site of injury
Increased membrane permeability to which of the following would cause an inhibitory postsynaptic potential (IPSP)? K+ Cl- acetylcholine either or both A and B
either or both A and B
EPSPs (excitatory postsynaptic potentials) occur when a) more potassium ions than usual leak out of a cell. b) more calcium ions than usual leak out of a cell. c) chloride ions enter a cell. d) extra sodium ions enter a cell. e) hyperpolarization occurs
extra sodium ions enter a cell
Damage to ependymal cells would most likely affect the a) formation of myelin sheaths. b) formation of cerebrospinal fluid. c) formation of ganglia. d) repair of axons.
formation of cerebrospinal fluid.
Which of the following is not involved in creating the resting potential of a neuron? a) diffusion of potassium ions out of the cell b) an excess of negative charges along the inner surface of the plasma membrane. c) greater membrane permeability for sodium ions than for potassium ions. d) greater membrane permeability for potassium ions than for sodium ions.
greater membrane permeability for sodium ions than for potassium ions
A movement of ions that increases the negativity of the resting membrane potential causes __________. repolarization depolarization hyperpolarization an action potentia
hyperpolarization
A simultaneous increase in membrane permeability to K+ and C1- in a resting nerve cell would have what effect? no effect, since the two would cancel each other depolarization repolarization hyperpolarization
hyperpolarization
Postsynaptic inhibition involves: hyperpolarization of postsynaptic membrane depolarization of postsynaptic membrane excitatory postsynaptic potential a sudden increase in permeability to sodium in the postsynaptic membrane
hyperpolarization of postsynaptic membrane
Voltage-gated channels are present a) at the motor end plate. b) on the surface of dendrites. c) in the membrane that covers axons. d) on the soma of neurons.
in the membrane that covers axons
Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. a) inactivation b) ion c) swinging d) repolarization
inactivation
Which of the following is the major function of myelin? protects the brain and spinal cord transmits action potentials from one neuron to another blocks postsynaptic potentials increases the rate of conduction of action potentials
increases the rate of conduction of action potentials
A signal that crosses a synapse between an axon and another neuron: is chemical usually goes from a dendrite to an axon involves two neurons touching each other is electrical
is chemical
Ion channels that are always open are known as a) leak channels b) mechanically-gated channels c) chemically gated channels. d) voltage-gated channels
leak channels
Graded potentials a) produce an effect that increases with distance from the point of stimulation. b) produce an effect that spreads actively across the membrane surface without diminishing. c) may be either a depolarization or a hyperpolarization d) are often all-or-none. e) always cause repolarization
may be either a depolarization or a hyperpolarization
After a stroke, what type of glial cell accumulates within the affected brain region? a) Schwann cells b) satellite cells c) oligodendrocytes d) microglia e) ependymal cells
microglia
Small, wandering cells that engulf cell debris and pathogens in the CNS are called a) astrocytes. b) satellite cells. c) oligodendrocytes. d) microglia e) ependymal cells.
microglia
The substance released at axonal endings to propagate a nerve impulse is known as a(n): ion neuromodulator neurotransmitter cholinesterase
neurotransmitter
The same ________ can have different effects depending on the properties of the ________. a) neurotransmitter; receptor b) receptor; neurotransmitter c) substrate; receptor d) hormone; neurotransmitter
neurotransmitter; receptor
Unmyelinated axons are __________. protected by a single Schwann cell only partially surrounded by myelin called nodes of Ranvier completely lacking any support from myelin
only partially surrounded by myelin
Schwann cells are glial cells responsible for __________. phagocytic activities in the neural tissue of the PNS producing the myelination around peripheral axons surrounding nerve cell bodies in peripheral ganglia secreting cerebrospinal fluid
producing the myelination around peripheral axons
The voltage that exists across the plasma membrane of an unstimulated cell is called the _______. depolarization resting membrane potential action potential graded potential
resting membrane potential
An action potential: will occur if the membrane is hyperpolarized by about 20-30 millivolts results from a sudden increase in membrane permeability to sodium followed by a slower increase in permeability to potassium varies in amplitude (strength) with the strength of the stimulus is caused by a sudden increase in activity of the Na-K pump
results from a sudden increase in membrane permeability to sodium followed by a slower increase in permeability to potassium
node of Ranvier
saltatory conduction
Glial cells that surround the neurons in ganglia are a) astrocytes. b) satellite cells c) oligodendrocytes. d) microglia. e) ependymal cells.
satellite cells
Tyson decides to travel overseas, but he does not get all the needed vaccines before he goes on the trip. While on his trip, he contracts diphtheria. Which type of glial cells are particularly at risk from this disease? Microglia Satellite cells Oligodendrocytes Schwann cells
schwann cells
The two ions that are primarily responsible for stabilizing the resting membrane potential are __________. potassium and chloride calcium and chloride sodium and potassium sodium and chloride
sodium and potassium
During the depolarization period of an action potential in a neuron: sodium permeability increases membrane permeability to potassium decreases the inside of the cell becomes more negative all of the above
sodium permeability increases
Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? specific sodium gates will open specific potassium gates will open a gate will open which allows for sodium and potassium to flow simultaneously specific calcium gates will open
specific sodium gates will open
When a second EPSP arrives at a single synapse before the effects of the first have disappeared, what occurs? a) spatial summation b) temporal summation c) inhibition of the impulse d) hyperpolarization
temporal summation
If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur, except a) the intracellular concentration of potassium ions will increase b) the neuron will slowly depolarize. c) the membrane will slowly lose its capacity to generate action potentials. d) the inside of the membrane will have a resting potential that is more positive than normal. e) the intracellular concentration of sodium ions will increase.
the intracellular concentration of potassium ions will increase
The sodium/potassium pump functions to pump: three sodium ions outside the cell and two potassium ions inside two sodium ions outside the cell and three potassium ions inside three sodium ions inside the cell and two potassium ions outside two sodium ions inside the cell and three potassium ions outside
three sodium ions outside the cell and two potassium ions inside
Which of the following is not a function of the nervous system? a) to sense the internal and external environments b) to integrate sensory information c) to coordinate voluntary and involuntary activities d) to direct long-term functions, such as growth e) to control peripheral effectors
to direct long-term functions, such as growth
Drug A inhibits the enzymatic breakdown of a neurotransmitter at the postsynaptic membrane, and this increases the magnitude of excitatory postsynaptic potentials (EPSPs) in the postsynaptic neuron. True of False: Drug A increases the probability of the postsynaptic neuron firing an action potential. true false
true
Graded potentials differ from action potentials in that graded potential: do not decrease in strength with distance traveled vary in magnitude with the strength of stimulus cannot be summed, or added together are hyperpolarizing only, whereas action potentials are depolarizing
vary in magnitude with the strength of stimulus
Which of the following does not influence the time necessary for a nerve impulse to be transmitted? a) length of the axon b) presence or absence of a myelin sheath c) diameter of the axon d) presence or absence of nodes e) whether or not the impulse begins in the CNS
whether or not the impulse begins in the CNS
Most CNS neurons lack centrioles. This observation explains a) why CNS neurons grow such long axons. b) why CNS neurons cannot regenerate. c) the ability of neurons to generate an action potential. d) the ability of neurons to communicate with each other.
why CNS neurons cannot regenerate
