Quiz 9: Neural Mechanisms

Branches that may occur along an axon are called Question 10 options: a) synapses. b) synaptic knobs. c) collaterals. d) hillocks.

collaterals.

Branches that may occur along an axon are called Question 17 options: a) synapses. b) synaptic knobs. c) collaterals .d) hillocks.

collaterals.

Small, wandering cells that engulf cell debris and pathogens in the CNS are called Question 12 options: a) astrocytes. 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 Question 6 options: a) astrocytes. b) satellite cells .c) oligodendrocytes. d) microglia. e) ependymal cells.

microglia.

receives signal from axon threshold node of Ranvier all-or-none event neurotransmitter single long process extending from neuron 1.saltatory conduction2.dendrite3."just sufficient" depolarization4.axon5.action potential6.acetylcholine

2, 3, 1, 5, 6, 4

In a typical neuron at rest, the Na-K ion exchange pump transports Question 2 options: 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.

The________ open or close in response to binding specific molecules. Question 15 options: 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. Question 19 options: a) Astrocytes b) Satellite cells c) Oligodendrocytes d) Microglia e) Ependymal cells

Ependymal cells

Increasing the intensity of a stimulus applied to a receptor will increase the amplitude of action potentials, assuming constant conditions. Question 14 options: True False

False

Increasing the intensity of a stimulus applied to a receptor will increase the amplitude of action potentials, assuming constant conditions. Question 8 options: True False

False

The ___________ are the most numerous type of neuron in the CNS. Question 2 options: a) Sensory neurons b) Motor neurons c) Unipolar neurons d) Bipolar neurons e) Interneurons

Interneurons

The ________ channels open or close in response to physical distortion of the membrane surface. Question 5 options: a) Voltage-gated b) Chemically gated c) Leak d) Mechanically gated e) Leak

Mechanically gated

Why do nerve impulses travel only in one direction? Question 1 options: a. Only the axon side of a neuron can release chemical transmitters. b. The impulse direction is controlled by the central nervous system. c. The orientation of the myelin sheath determines the direction of the impulse. d. Depolarization cannot move through the neuron cell body.

Only the axon side of a neuron can release chemical transmitters.

Why do nerve impulses travel only in one direction? Question 11 options: a. The impulse direction is controlled by the central nervous system. b. Depolarization cannot move through the neuron cell body. c. The orientation of the myelin sheath determines the direction of the impulse. d. Only the axon side of a neuron can release chemical transmitters.

Only the axon side of a neuron can release chemical transmitters.

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? Question 11 options: 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.

Puffer fish poison blocks voltage-gated sodium channels like a cork. What effect would this neurotoxin have on the function of neurons? Question 17 options: 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.

If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential? Question 12 options: 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.

If the potassium permeability of a resting neuron increases above the resting permeability, what effect will this have on the transmembrane potential? Question 5 options: 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? Question 2 options: 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. Question 16 options: True False

True

Temporal summation occurs when: Question 9 options: a. many presynaptic neurons transmit signals at the same time to one postsynaptic neuron b. a presynaptic neuron is inhibited by neuromodulators c. a single presynaptic neuron fires a rapid series of many signals at one postsynaptic neuron d. many presynaptic neurons inhibit 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: Question 15 options: a. resting potential b. absolute refractory period c. stable period d. relative refractory period

absolute refractory period

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: Question 17 options: a. resting potential b. relative refractory period c. absolute refractory period d. stable period

absolute refractory period

Cholinergic synapses release the neurotransmitter Question 20 options: a) norepinephrine. b) adrenalin. c) serotonin. d) acetylcholine.

acetylcholine.

Cholinergic synapses release the neurotransmitter Question 7 options: a) norepinephrine. b) adrenalin. c) serotonin. d) acetylcholine.

acetylcholine.

A typical nerve cell: Question 10 options: 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

A typical nerve cell: Question 2 options: a. conducts an impulse from one part of the nervous system to another b. consists of a cell body, dendrites, and axon c. releases a chemical transmitter substance from the axon fiber d. all of the above

all of the above

In the process of continuous action potential propagation, Question 10 options: 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

In the process of continuous action potential propagation, Question 7 options: 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? Question 9 options: 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

Which of the following is a function of neuroglia? Question 11 options: 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 is a function of neuroglia? Question 5 options: 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

The all-or-none principle states that Question 20 options: 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) Question 20 options :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? Question 4 options: a. hyperpolarization b. arrival of an action potential c. neurotransmitters binding to the presynaptic membrane d. neurotransmitter synthesis

arrival of an action potential

The largest and most numerous neuroglia in the CNS that absorb and recycle neurotransmitters are the Question 13 options: a) astrocytes. b) ependymal cells. c) microglia. d) oligodendrocytes. e) none of the above

astrocytes.

The site in the neuron where EPSPs and IPSPs are integrated is the Question 3 options: a) synaptic knob. b) electrical synapse. c) axon hillock. d) dendritic membrane.

axon hillock.

If the permeability of a resting axon to sodium ion increases, Question 5 options: 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: Question 19 options: a. by depolarization of successive regions of membrane as a result of local current flow b. towards the soma of the presynaptic neuron c. by chemical transmitters d. 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 Question 19 options: a) sodium .b) potassium .c) calcium. d) chloride. e) magnesium.

calcium.

The ion that triggers the release of acetylcholine into the synaptic cleft is Question 8 options :a) sodium. b) potassium. c) calcium. d) chloride. e) magnesium.

calcium.

Efferent neurons: Question 8 options: a. control only involuntary movements b. carry sensory information c. carry action potentials from muscles or glands to the CNS d. carry motor signals

carry motor signals

The resting membrane potential of a nerve cell is: Question 3 options: a. not dependent on the Na - K pump for its maintenance b. about -5mV inside negative to outside c. caused by unequal distribution of Na+ and K+ on each side of the cell membrane d. typically about +50 mV inside positive

caused by unequal distribution of Na+ and K+ on each side of the cell membrane

Functions of astrocytes include all of the following, except Question 1 options: 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.

Increased membrane permeability to which of the following would cause an inhibitory postsynaptic potential (IPSP)? Question 20 options: a. K+ b. Cl- c. acetylcholine d. either or both A and B

either or both A and B

EPSPs (excitatory postsynaptic potentials) occur when Question 17 options: 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 Question 16 options: a) formation of myelin sheaths. b) formation of cerebrospinal fluid. c) formation of ganglia. d) repair of axons.

formation of cerebrospinal fluid.

Damage to ependymal cells would most likely affect the Question 4 options: 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? Question 15 options: 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 simultaneous increase in membrane permeability to K+ and C1- in a resting nerve cell would have what effect? Question 14 options: a. no effect, since the two would cancel each other b. depolarization c. repolarization d. hyperpolarization

hyperpolarization

Postsynaptic inhibition involves: Question 4 options: a. hyperpolarization of postsynaptic membrane b. depolarization of postsynaptic membrane c. excitatory postsynaptic potential d. a sudden increase in permeability to sodium in the postsynaptic membrane

hyperpolarization of postsynaptic membrane

Voltage-gated channels are present Question 13 options: 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. Question 14 options: a) inactivation b) ion c) swinging d) repolarization

inactivation

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate. Question 6 options: a) inactivation b) ion c) swinging d) repolarization

inactivation

Which of the following is the major function of myelin? Question 1 options: a. transmits action potentials from one neuron to another b. protects the brain and spinal cord c. increases the rate of conduction of action potentials d. blocks postsynaptic potentials

increases the rate of conduction of action potentials

A signal that crosses a synapse between an axon and another neuron: Question 11 options: is chemical involves two neurons touching each other usually goes from a dendrite to an axon is electrical

is chemical

Ion channels that are always open are known as Question 1 options: a) leak channels .b) mechanically-gated channels c) chemically gated channels. d) voltage-gated channels.

leak channels.

Graded potentials Question 18 options: 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? Question 18 options: a) Schwann cells b) satellite cells c) oligodendrocytes d) microglia e) ependymal cells

microglia

The sodium-potassium ion exchange pump Question 14 options: 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.

The substance released at axonal endings to propagate a nerve impulse is known as a(n): Question 13 options: a. ion b. neuromodulator c. neurotransmitter d. cholinesterase

neurotransmitter

The same ________ can have different effects depending on the properties of the ________. Question 19 options: a) neurotransmitter; receptor b) receptor; neurotransmitter c) substrate; receptor d) hormone; neurotransmitter

neurotransmitter; receptor

An action potential: Question 10 options: a. will occur if the membrane is hyperpolarized by about 20-30 millivolts b. results from a sudden increase in membrane permeability to sodium followed by a slower increase in permeability to potassium c. varies in amplitude (strength) with the strength of the stimulus d. 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

Glial cells that surround the neurons in ganglia are Question 12 options: a) astrocytes. b) satellite cells. c) oligodendrocytes. d) microglia. e) ependymal cells.

satellite cells.

Glial cells that surround the neurons in ganglia are Question 18 options: a) astrocytes .b) satellite cells. c) oligodendrocytes. d) microglia. e) ependymal cells.

satellite cells.

During the depolarization period of an action potential in a neuron: Question 4 options: a. sodium permeability increases b. membrane permeability to potassium decreases c. the inside of the cell becomes more negative d. 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? Question 13 options: a. specific sodium gates will open b. specific potassium gates will open c. a gate will open which allows for sodium and potassium to flow simultaneously d. specific calcium gates will open

specific sodium gates will open

Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? Question 7 options: a. specific sodium gates will open b. specific potassium gates will open c. a gate will open which allows for sodium and potassium to flow simultaneously d. 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? Question 7 options: 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 Question 16 options: 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.

If the sodium-potassium pumps in the plasma membrane fail to function, all of the following occur, except Question 3 options: 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: Question 3 options: a. three sodium ions outside the cell and two potassium ions inside b. two sodium ions outside the cell and three potassium ions inside c. three sodium ions inside the cell and two potassium ions outside d. 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? Question 18 options: 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. Question 6 options: true false

true

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. Question 9 options: true false

true

Graded potentials differ from action potentials in that graded potential: Question 15 options: a. are hyperpolarizing only, whereas action potentials are depolarizing b. do not decrease in strength with distance traveled c. vary in magnitude with the strength of stimulus d. cannot be summed, or added together

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? Question 8 options: 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

Which of the following does not influence the time necessary for a nerve impulse to be transmitted? Question 9 options: 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 Question 12 options: 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.