Unit 2 week 1 homework questions
What component of the reflex arc determines the response to a stimulus? integration center effector sensory neuron receptor
integration center
The small space between the sending neuron and the receiving neuron is the
synaptic cleft
An action potential releases neurotransmitter from a neuron by opening which of the following channels? chemically gated Ca2+ channels voltage-gated Ca2+ channels voltage-gated Na+ channels
voltage-gated Ca2+ channels
Which ion channel opens in response to a change in membrane potential and participates in the generation and conduction of action potentials? leakage channel voltage-gated channel mechanically-gated channel ligand-gated channel
voltage-gated channel
Assume you have a membrane with only potassium leakage channels. The RMP is -90mV. Predict the RMP if we add Na+Na+ leakage channels.The most likely RMP value of Na+Na+ is __________. -50 mV +90 mV -70 mV -90 mV
-70 mV
Which of the following is false or incorrect? A nerve impulse occurs if the excitatory and inhibitory effects are equal. An excitatory postsynaptic potential occurs if the excitatory effect is greater than the inhibitory effect but less than threshold. An inhibitory postsynaptic potential occurs if the inhibitory effect is greater than the excitatory, causing hyperpolarization of the membrane.
A nerve impulse occurs if the excitatory and inhibitory effects are equal.
Which of the following will occur when an excitatory postsynaptic potential (EPSP) is being generated on the dendritic membrane? A single type of channel will open, permitting simultaneous flow of sodium and potassium. Specific potassium gates will open. Sodium gates will open first, then close as potassium gates open. Specific sodium gates will open.
A single type of channel will open, permitting simultaneous flow of sodium and potassium.
Select the correct statement regarding chemical synapses. An action potential reaching the axon terminal causes a chemical signal to be transmitted across the synaptic cleft to the postsynaptic cell. Neurotransmitter receptors are located on the axons terminals of cells. The release of neurotransmitter molecules gives cells the property of being electrically coupled.
An action potential reaching the axon terminal causes a chemical signal to be transmitted across the synaptic cleft to the postsynaptic cell.
How is an action potential propagated along an axon? An efflux of potassium from the current action potential depolarizes the adjacent area. Stimuli from the graded (local) potentials from the soma and dendrites depolarize the entire axon. An influx of sodium ions from the current action potential depolarizes the adjacent area.
An influx of sodium ions from the current action potential depolarizes the adjacent area.
When a neurotransmitter like acetylcholine is acting in an excitatory manner which of the following is likely a result of the acetylcholine acting on the postsynaptic cell? Chemically gated sodium channels will be closed. Chemically gated chloride channels will open. Chemically gated sodium channels will open.
Chemically gated sodium channels will open.
What type of conduction takes place in unmyelinated axons? Synaptic transmission Saltatory conduction Electrical conduction Continuous conduction
Continuous conduction
The effect of acetylcholine can be stimulating or inhibiting. Which of the following gives the best explanation for why this is so? Postsynaptic cells have a dynamic and changing metabolism and respond differently at different times. Acetylcholine has many different forms. Acetylcholine has a "dose effect." Larger doses are stimulating while small doses inhibit. Different postsynaptic cells will have different receptors.
Different postsynaptic cells will have different receptors.
Which description of synapses is not correct? Direct signaling involves the activation of G proteins .Excitatory synapses cause depolarization. Second messengers can activate gene activities in the postsynaptic neuron.
Direct signaling involves the activation of G proteins
Which description best fits graded potentials? Graded potentials are found only along the axon of a neuron. Graded potentials are all-or-nothing events. Graded potentials are caused only by the influx of sodium ions. Graded potentials can result in either depolarization or hyperpolarization of the membrane and vary in strength.
Graded potentials can result in either depolarization or hyperpolarization of the membrane and vary in strength.
Where do most action potentials originate? Cell body Axon terminal Nodes of Ranvier Initial segment
Initial segment
In which type of axon will velocity of action potential conduction be the fastest? Unmyelinated axons with the largest diameter Myelinated axons with the largest diameter Myelinated axons with the smallest diameters
Myelinated axons with the largest diameter
During the action potential of a neuron, which ion is primarily crossing the membrane during the depolarization phase, and in which direction is the ion moving? K+ is exiting the cell. K+ is entering the cell .Na+ is exiting the cell. Na+ is entering the cell.
Na+ is entering the cell.
Which of the following does NOT describe the process of summation? Two EPSPs occur close enough in time to bring the cell to threshold. One EPSP and one IPSP cancel each other out. One EPSP fails to bring the cell to threshold.
One EPSP fails to bring the cell to threshold.
Which of the following statements is correct regarding the polarization of a neuronal membrane and the formation of a resting membrane potential? Sodium/Potassium pumps maintain concentration gradients; sodium and potassium move down their concentration gradients through leakage channels. As Na+ leaks across the membrane, that establishes a negative charge inside the membrane. As sodium leaks into the cell, the inside of the cell becomes more negative. A resting potential can be generated without the energy as an input.
Sodium/Potassium pumps maintain concentration gradients; sodium and potassium move down their concentration gradients through leakage channels.
Imagine that the cell membrane from the previous problem becomes more permeable to Na+Na+. Predict how this will affect the RMP. The RMP will be unaffected. The RMP will be zero .The RMP will be more negative. The RMP will be more positive.
The RMP will be more positive.
In a lab you are conducting tests with various chemicals and neurotransmitter receptors. You notice that exposed frog muscle cells depolarize when you add the chemical nicotine to the acetylcholine (ACh) receptors. What does this tell us about the relationship between neurotransmitters and their receptors? The effect of a neurotransmitter is based on the properties of the receptor more than the neurotransmitter. Neurotransmitter receptors only bind specifically with their neurotransmitter. The effect of a neurotransmitter is based on the properties of the neurotransmitter more than the receptor.
The effect of a neurotransmitter is based on the properties of the receptor more than the neurotransmitter.
Why does regeneration of the action potential occur in one direction, rather than in two directions? The activation gates of voltage-gated K+ channels open in the node, or segment, that has just depolarized. The activation gates of voltage-gated Na+ channels close in the node, or segment, that has just depolarized. The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential.
The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential.
If a postsynaptic cell is stimulated to threshold by temporal summation this implies that ________. the postsynaptic cell can be influenced by only one presynaptic cell the presynaptic neuron is sending frequent IPSP a presynaptic neuron is sending frequent EPSP
a presynaptic neuron is sending frequent EPSP
The mechanism by which the neurotransmitter is returned to a presynaptic neuron's axon terminal is specific for each neurotransmitter. Which of the following neurotransmitters is broken down by an enzyme before being returned? acetylcholine glutamate
acetylcholine
The term central nervous system refers to the ________.
brain and spinal cord
Binding of a neurotransmitter to its receptors opens __________ channels on the __________ membrane.
chemically gated; postsynaptic
During the action potential, when does sodium permeability initially DECREASE? during repolarization during the peak of depolarization during hyperpolarization
during hyperpolarization
Binding of the neurotransmitter to its receptor causes the membrane to ______ either depolarize or hyperpolarize depolarize hyperpolarize
either depolarize or hyperpolarize
These cells in the CNS have cilia that move in order to circulate cerebrospinal fluid. microglia oligodendrocytes astrocytes ependymal cells
ependymal cells
Neurotransmitter is released from presynaptic neurons through what mechanism?
exocytosis
An inhibitory postsynaptic potential (IPSP) is associated with ________.
hyperpolarization
When a neurotransmitter like GABA is acting in an inhibitory manner which of the following is likely a result of the GABA acting on the postsynaptic cell? depolarization of the postsynaptic cell membrane influx of positively charged ions into the postsynaptic cell opening of chemically gated sodium channels hyperpolarization of the postsynaptic cell membrane
hyperpolarization of the postsynaptic cell membrane
A molecule that carries information across a synaptic cleft is a
neurotransmitter
In multiple sclerosis, the cells that are the target of an autoimmune attack are the _________. neurons muscle cells Schwann cells oligodendrocytes
oligodendrocytes
In the brain, vision originates in the rods and cones in the retina. Separate regions of the brain decode basic information, like color, shapes, intensity of light, and there are other regions that decode information like position in space, and awareness of patterns. As you use your visual system, all of these regions are working simultaneously. This simultaneous awareness of all regions working at the same time is due to which processing pattern listed below? parallel processing oscillative processing serial processing
parallel processing
Which of the following is NOT a type of circuit? pre-synaptic circuits converging circuits diverging circuits reverberating circuit
pre-synaptic circuits
In a synapse, neurotransmitters are stored in vesicles located in the __________. synaptic cleft presynaptic neuron postsynaptic neuron
presynaptic neuron
In addition to diffusion, what are two other mechanisms that terminate neurotransmitter activity?' reuptake and degradation reuptake and inhibition excitation and degradation
reuptake and degradation
Which neuron circuit pattern is involved in the control of rhythmic activities such as breathing? diverging circuit reverberating circuit converging circuit parallel after-discharge circuit
reverberating circuit
Cranial nerve II, the optic nerve, sends nerve impulses to the brain carrying information about the things we see. These nerve fibers most likely belong to which division of the nervous system? sensory (afferent) division somatic nervous system sympathetic division parasympathetic division
sensory (afferent) division
Nerve impulses leading to the brain carry information about cool temperatures on the skin. The nerve fibers sending these signals will most likely belong to which division of the nervous system? sensory (afferent) division somatic nervous system sympathetic division parasympathetic division
sensory (afferent) division
Which of the following describes the excitatory postsynaptic potential? moves membrane potential away from threshold short distance depolarization opens K+ or Cl- channels short distance hyperpolarization
short distance depolarization
Which is the main receptive portion of the neuron? the dendrite the synapse the cell body or soma the axon
the dendrite
Which criterion is used to functionally classify neurons? the number of processes extending from the cell body neuron the direction in which the nerve impulse travels relative to the central nervous system whether the nerve fibers are myelinated or unmyelinated whether the neurons are found within the CNS or the PNS
the direction in which the nerve impulse travels relative to the central nervous system
If a motor neuron in the body were stimulated by an electrode placed about midpoint along the length of the axon, ________. the impulse would move to the axon terminal only, and the muscle contraction would occur the impulse would move to the axon terminal only the impulse would spread bidirectionally
the impulse would spread bidirectionally
If a postsynaptic neuron is stimulated to threshold by spatial summation this implies that ________. the postsynaptic cell has a lower than normal threshold the postsynaptic cell has many synapses with many presynaptic neurons the postsynaptic cell is slow to repolarize
the postsynaptic cell has many synapses with many presynaptic neurons
During depolarization, the inside of the neuron's membrane becomes less negative.
true
What opens first in response to a threshold stimulus? Voltage-gated K+ channels Voltage-gated Na+ channels
Voltage-gated Na+ channels
What is the first change to occur in response to a threshold stimulus? Voltage-gated K+ channels change shape, and their activation gates open. Voltage-gated Na+ channels change shape, and their activation gates open. Voltage-gated Na+ channels change shape, and their inactivation gates close.
Voltage-gated Na+ channels change shape, and their activation gates open.
What type of channel on the postsynaptic membrane binds neurotransmitter? a mechanically gated channel a chemically gated channel a leakage channel
a chemically gated channel
What is meant by an EPSP? a localized change in the membrane potential that always results in threshold being reached a localized change in the membrane potential resulting in a less negative membrane voltage a localized change in the membrane potential resulting in a more negative membrane voltage
a localized change in the membrane potential resulting in a less negative membrane voltage
A postsynaptic cell can be a neuron, a muscle cell, or a secretory cell. What is an example of a presynaptic cell? a Schwann cell a neuron a muscle cell a secretory cell
a neuron
The velocity of the action potential is fastest in which of the following axons? a small myelinated axon a small unmyelinated axon a large unmyelinated axon
a small myelinated axon
What does the central nervous system use to determine the strength of a stimulus? type of stimulus receptor size of action potentials origin of the stimulus frequency of action potentials
frequency of action potentials
Collections of nerve cell bodies outside the central nervous system are called ________. ganglia nerves tracts nuclei
ganglia
Which of the following is NOT a function of dendrites? produce short-distance signals called graded potentials generate nerve impulses and transmit them away from the cell body provide enormous surface area for receiving signals from other neurons convey incoming messages toward the cell body
generate nerve impulses and transmit them away from the cell body
Events that occur during synaptic activity are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Voltage-gated calcium channels open (b) Neurotransmitter binds to receptors (c) Action potential arrives at axon terminal (d) Neurotransmitter is removed from the synaptic cleft (e) Neurotransmitter released into synaptic cleft (f) Graded potential generated in postsynaptic cell
(c) Action potential arrives at axon terminal (a) Voltage-gated calcium channels open (e) Neurotransmitter released into synaptic cleft (b) Neurotransmitter binds to receptors (f) Graded potential generated in postsynaptic cell (d) Neurotransmitter is removed from the synaptic cleft
Cl−Cl− is a common, negatively charged extracellular ion. Predict the effect on the RMP if many Cl−Cl− gated channels are suddenly opened. The membrane would become hypopolarized or have less charge separation across the membrane. The RMP would become more positive. A more negative RMP would result. There would be no change in the RMP.
A more negative RMP would result.
What is the role of calcium in synaptic activity? Calcium diffuses across the synaptic cleft and binds to receptors on the postsynaptic neuron. Calcium influx into the axon causes an action potential to propagate into the synaptic terminal. Calcium degrades neurotransmitter in the synaptic cleft. Calcium influx into the synaptic terminal causes vesicle fusion.
Calcium influx into the synaptic terminal causes vesicle fusion.
During the hyperpolarization phase of the action potential, when the membrane potential is more negative than the resting membrane potential, what happens to voltage-gated ion channels? K+ channels close. Na+ channels go from an inactivated state to a closed state. K+ channels close. Na+ channels open .K+ channels open. Na+ channels inactivate.
K+ channels close. Na+ channels go from an inactivated state to a closed state.
What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization? Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open. Activation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open. Activation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.
Inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open.
Which of the following correctly describes a graded potential? It is initiated by voltage changes in the membrane. It has a depolarization, repolarization, and hyperpolarization phase. It travels long distances. It can have amplitudes of various sizes.
It can have amplitudes of various sizes.
Which of the following is the clearest example of a neuronal membrane's selective permeability? The Na+-K+ pump only transports Na+ and K+ ions. K+ ions can diffuse across the membrane more easily than Na+ ions. The concentration gradient for Na+ ions is inward, but the concentration gradient for K+ ions is outward.
K+ ions can diffuse across the membrane more easily than Na+ ions.
During an action potential, hyperpolarization beyond (more negative to) the resting membrane potential is primarily due to __________. K+ ions diffusing through voltage-gated channels Na+-K+ pump activity Na+ diffusing through voltage-gated channels
K+ ions diffusing through voltage-gated channels
The repolarization phase of the action potential, where voltage becomes more negative after the +30mV peak, is caused primarily by __________. Na+ ions leaving the cell through voltage-gated channels Na+ ions transported out of the cell by the Na+-K+ pump K+ ions entering the cell through voltage-gated channels K+ ions leaving the cell through voltage-gated channels
K+ ions leaving the cell through voltage-gated channels
During an action potential, the rapid decrease in sodium permeability and simultaneous increase in potassium permeability is responsible for __________.
repolarization
Which of the following does NOT describe conditions that occur during an action potential? Na+ is used to repolarize the membrane. The Na+/K+ pump reestablishes resting concentration gradients. After initial depolarization, K+ now has both an electrical and a chemical gradient drawing it out of the cell. Na+ enters the cell through voltage-gated channels, causing a reversal of the resting membrane potential
Na+ is used to repolarize the membrane.
What is the direct role of neurotransmitter at a chemical synapse? Neurotransmitter causes a graded potential in the postsynaptic cell. Neurotransmitter causes vesicles to fuse with the presynaptic membrane. Neurotransmitter causes calcium to flood into the presynaptic cell. Neurotransmitter binds to receptors on the postsynaptic cell membrane and allows ions to diffuse across the membrane.
Neurotransmitter binds to receptors on the postsynaptic cell membrane and allows ions to diffuse across the membrane.
What characterizes repolarization, the second phase of the action potential?
Once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV
Some nerve fibers of the peripheral nervous system have the ability to regenerate after damage has occurred. Which of the following cells is most responsible for aiding in this regulation? oligodendrocytes Schwann cells astrocytes satellite cells
Schwann cells
Which of the following best describes the Na+ and K+ concentrations across a neuron's plasma membrane? The Na+ concentration is higher outside the cell compared to inside. The K+ concentration is higher inside the cell compared to outside. Both Na+ and K+ concentrations are higher outside the cell compared to inside. The Na+ concentration is higher inside the cell compared to outside. The K+ concentration is higher outside the cell compared to inside. Both Na+ and K+ concentrations are higher inside the cell compared to outside.
The Na+ concentration is higher outside the cell compared to inside. The K+ concentration is higher inside the cell compared to outside.
Tetraethylammonium (TEA) blocks voltage-gated K+ channels such that K+ cannot pass even when the channels are open. However, TEA leaves K+ leakage channels largely unaffected. How would you expect the action potential to change if you treated a neuron with TEA? The membrane would depolarize and repolarize as usual, but no hyperpolarization beyond (more negative to) the resting membrane potential would occur.The action potential would fail. Once the voltage reached threshold, it would return to the resting membrane potential. The action potential would depolarize as usual, but the repolarization phase would take longer, causing the action potential to be more broad in time.
The action potential would depolarize as usual, but the repolarization phase would take longer, causing the action potential to be more broad in time.
Why does the action potential only move away from the cell body? The flow of the sodium ions only goes in one direction—away from the cell body The areas that have had the action potential are refractory to a new action potential.
The areas that have had the action potential are refractory to a new action potential.
You are going to record RMP from a cell using an electrode. You place your electrode and record a resting membrane potential every millisecond. You record an initial value of -70mV; however, over time you notice that your recordings become more and more positive until the RMP reaches 0mV. Assuming that Na+Na+ and K+K+ are the major determinants of RMP in this cell, which of the following could best explain your results? The cell is becoming depleted of K+K+. The cell's Na+Na+ leakage channels have stopped functioning. The cell's Na+Na+-K+K+ ATPase pumps have stopped functioning. The cell is becoming depleted of Na+Na+.
The cell's Na+Na+-K+K+ ATPase pumps have stopped functioning.
Many neurons have many short, branching extensions called dendrites. What is the benefit of these structures for a neuron? There is a large area for production of chemicals used to signal other neurons. There is a large amount of space for myelin to form and make electrical conduction more efficient. The dendrites provide a large surface area for connections from other neurons. There is a large surface area to send signals to other cells
The dendrites provide a large surface area for connections from other neurons.
Which of the following is NOT a difference between graded potentials and action potentials? Greater stimulus intensity results in larger graded potentials, but not larger action potentials. Graded potentials can result from the opening of chemically gated channels; action potentials require the opening of voltage-gated channels. The magnitude of action potentials decrease as the impulse travels further away from the start of the impulse while graded potentials do not decrease in magnitude. Graded potentials occur along dendrites, whereas action potentials occur along axons.
The magnitude of action potentials decrease as the impulse travels further away from the start of the impulse while graded potentials do not decrease in magnitude.
What characterizes depolarization, the first phase of the action potential? The membrane potential changes to a much more negative value. The membrane potential changes to a less negative (but not a positive) value. The membrane potential changes from a negative value to a positive value.
The membrane potential changes from a negative value to a positive value.
What event triggers the generation of an action potential? The membrane potential must depolarize from the resting voltage of -70 mV to its peak value of +30 mV. The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV. The membrane potential must hyperpolarize from the resting voltage of -70 mV to the more negative value of -80 mV.
The membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV.
What is the function of the myelin sheath? The myelin sheath increases the insulation along the entire length of the axon. The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals. The myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals.
The myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals.
You discover that a new chemical compound interacts with K+ voltage-dependent channels. What would be the effect on a neuron if the chemical came into contact with the axonal membrane? The cell would be unable to generate a resting potential. The cell would die. The neuron would be unable to repolarize.
The neuron would be unable to repolarize.
Which mechanism allows the rabies virus to gain access to the central nervous system (CNS)? The rabies virus enters the Schwann cells of the peripheral nervous system and uses salutatory movement to move toward the CNS. The rabies virus uses retrograde movement along the neuronal axon. The rabies virus uses anterograde along the neuronal axon. Rabies virus moves through the blood vessels to the CNS.
The rabies virus uses retrograde movement along the neuronal axon.
Suppose a drug is developed that blocks K+ leakage channels. The drug prevents ions from passing through those channels. If this drug was applied to a neuron, what would be the most immediate effect on that neuron? The resting membrane potential would become more negative. The concentration gradient for Na+ would decrease. The resting membrane potential would become less negative (more positive).
The resting membrane potential would become less negative (more positive).
What is the basic condition when a neuron is described as polarized? Na+ is found outside of the neuron and K+ is found inside of the cell. Na+ is found outside of the neuron. There are large, protein anions inside the neuron. There is a separation of positive and negative charges across a membrane.
There is a separation of positive and negative charges across a membrane.
Which of the following is NOT a characteristic of neurons? They have an exceptionally high metabolic rate. They are mitotic. They have extreme longevity. They conduct impulses.
They are mitotic.
Which of the following is NOT true of graded potentials? They increase amplitude as they move away from the stimulus point. They can be called postsynaptic potentials. They are short-lived. They can form on receptor endings.
They increase amplitude as they move away from the stimulus point.
The depolarization phase of an action potential is punctuated by the closing of inactivation gates in the voltage gated sodium ion channels. All of the following are consequences of this inactivation except one. Choose the statement below that is not a consequence of the closing of inactivating gates. This stops the depolarization of the axon membrane. This limits the frequency of action potentials down the axon. This allows for the efflux (diffusion out) of potassium ions, resulting in the repolarization of the cell. This allows for the one way transmission of action potential down the axon.
This allows for the efflux (diffusion out) of potassium ions, resulting in the repolarization of the cell.
Local anesthetics block voltage-gated Na+ channels, but they do not block mechanically gated ion channels. Sensory receptors for touch (and pressure) respond to physical deformation of the receptors, resulting in the opening of specific mechanically gated ion channels. Why does injection of a local anesthetic into a finger still cause a loss of the sensation of touch from the finger? The local anesthetic prevents Na+ from causing the initial depolarization of this sensory receptor. The local anesthetic prevents any type of repolarization of this sensory receptor. Touch stimulation of this sensory receptor requires that there be a simultaneous opening of voltage-gated Na+ channels and mechanically gated ion channels. Touch stimulation of this sensory receptor will open the mechanically gated ion channels, but action potentials are still not initiated because propagation of an action potential requires the opening of voltage-gated Na+ channels.
Touch stimulation of this sensory receptor will open the mechanically gated ion channels, but action potentials are still not initiated because propagation of an action potential requires the opening of voltage-gated Na+ channels.
Cold sores on the skin of the mouth occur when herpes simplex viruses that are dormant in neural ganglia become active and travel to the skin of the mouth. Which of the following is the mechanism by which these viruses travel from the ganglia (located within the head) to the skin of the mouth? transport by nerve impulses that travel down the axons anterograde transport retrograde transport
anterograde transport
The concentration of ions in the chemical environment surrounding the neurons must be tightly regulated for neurons to function properly. Which of the following cells is most responsible for this? oligodendrocytes Schwann cells astrocytes satellite cells
astrocytes
During what part of the action potential do voltage-gated Na+ channels begin to inactivate (their inactivation gates close)? at the beginning of an action potential, as the membrane potential reaches threshold at the end of the repolarization phase, as the membrane potential briefly passes its resting value at the end of the depolarization phase, as the membrane potential approaches its peak value
at the end of the depolarization phase, as the membrane potential approaches its peak value
What kinds of gated channels are typically found in high concentrations at the dendrites?
chemically gated
Which component has a role in the postsynaptic cell during synaptic activity? chemically gated channels axon terminal Vesicles filled with neurotransmitter calcium channels
chemically gated channels
An action potential is self-regenerating because __________. depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment repolarizing currents established by the efflux of Na+ flow down the axon and trigger an action potential at the next segment depolarizing currents established by the influx of K+ flow down the axon and trigger an action potential at the next segment
depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment
Loss of function in the enzyme acetylcholine esterase would result in which of the following? inability to destroy and remove acetylcholine from the synaptic cleft inability to release acetylcholine stimulation of the production of acetylcholine
inability to destroy and remove acetylcholine from the synaptic cleft
A neuron that has as its primary function the job of connecting other neurons is called a(n) ________. efferent neuron interneuron glial cell afferent neuron
interneuron
When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron. ion channels in the plasma membrane of the sending neuron open. ion channels in the plasma membrane of the receiving neuron open.
ion channels in the plasma membrane of the receiving neuron open.
What is the major role of the Na+-K+ pump in maintaining the resting membrane potential? maintaining the concentration gradients for Na+ and K+ across the cell membrane hydrolyzing ATP making the membrane potential negative by moving more Na+ ions out of the cell than K+ ions into the cell
maintaining the concentration gradients for Na+ and K+ across the cell membrane
Meningitis can be caused by infection of the central nervous system by bacteria. Which cells would be most responsible for removing the infection? microglia oligodendrocytes astrocytes ependymal cells
microglia
Which of the following types of glial cells monitors the health of neurons, and can transform into a special type of macrophage to protect endangered neurons? microglia oligodendrocytes astrocytes ependymal cells
microglia
Which of the following would increase the membrane permeability to K+? more Na+ leakage channels a greater concentration gradient for K+ more negative membrane potential more K+ leakage channels
more K+ leakage channels
Which of the choices below describes the ANS? motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands sensory neurons that convey information from somatic receptors in the head, body wall, and limbs and from receptors from the special senses of vision, hearing, taste, and smell to the CNS sensory and motor neurons that supply the digestive tract motor fibers that conduct nerve impulses from the CNS to skeletal muscles
motor fibers that conduct nerve impulses from the CNS to smooth muscle, cardiac muscle, and glands
Ependymal cells line many open cavities in the central nervous system (CNS). Ependymal cells have cilia on the side of the cell that face these openings. What is the most likely function of these ciliated cells? act as macrophage cells to destroy microorganisms or neuronal debris exchange of nutrients between the circulatory system and neurons create myelin sheaths for CNS cells movement and circulation of cerebrospinal fluid
movement and circulation of cerebrospinal fluid
Complete the following sentence. The operation of the Na+−K+Na+−K+ ATPase pump __________ .releases 1 Na+Na+ to the ECF and 1 K+K+ to the cytoplasm moves 2 Na+Na+ to the ECF and 3 K+K+ to the cytoplasm releases 3 K+K+ to the ECF moves 3 Na+Na+ to the ECF and 2 K+K+ to the cytoplasm
moves 3 Na+Na+ to the ECF and 2 K+K+ to the cytoplasm
The interior surface of a neuron's plasma membrane at resting membrane potential will have a ________. negative charge and contains more sodium than outside of the cell negative charge and contains less sodium than outside of the cell positive charge and contains less sodium than outside of the cell
negative charge and contains less sodium than outside of the cell
Like all cells, the neurons' internal organization dictates its function. Neurons have relatively many mitochondria, an extensive network of rough endoplasmic reticulum and many clusters of ribosomes. These cellular features indicate all of the following EXCEPT ________. neurons have a relatively high consumption of oxygen neurons have stable, relatively unchanging internal environments neurons must meet a high demand for ATP neurons produce many proteins
neurons have stable, relatively unchanging internal environments
Schwann cells are functionally similar to ________. oligodendrocytes Schwann cells astrocytes satellite cells
oligodendrocytes
Nerve impulses are sent to slow the heart's rate of contraction. The nerve fibers sending these signals will most likely belong to which division of the nervous system? sensory (afferent) division somatic nervous system sympathetic division parasympathetic division
parasympathetic division
Nerve impulses leading to the skeletal muscle carry information to direct movement. The nerve fibers sending these signals will most likely belong to which division of the nervous system? sensory (afferent) division somatic nervous system sympathetic division parasympathetic division
somatic nervous system
What division of the nervous system is most specifically responsible for voluntary motor control? central nervous system sympathetic nervous system parasympathetic nervous system somatic nervous system
somatic nervous system
Imagine you changed the concentration of K+ outside a neuron such that the resting membrane potential changed to -80 mV (from the normal resting value of -70 mV). What have you changed? the electrical gradients and concentration gradients for both Na+ and K+. the electrical gradient for K+ the concentration gradient for K+ the electrical gradient for K+ and the concentration gradient for K+
the electrical gradient for K+ and the concentration gradient for K+
A second nerve impulse cannot be generated until ________. all sodium gates are closed the Na ions have been pumped back into the cell the membrane potential has been reestablished
the membrane potential has been reestablished
If a signal from a sending neuron makes the receiving neuron more negative inside, the sending neuron becomes more positive inside. the sending neuron becomes more negative inside. the receiving neuron is more likely to generate an action potential. the receiving neuron immediately generates an action potential. the receiving neuron is less likely to generate an action potential.
the receiving neuron is less likely to generate an action potential.
Hypothetically, what would be the most immediate effect of doubling the number of Na+ leakage channels in the plasma membrane? The resting membrane potential would become less negative (more positive). The resting membrane potential would become more negative. The inward concentration gradient for Na+ would become larger.
the resting membrane potential would become less negative (more positive).
What is the electrochemical gradient of an ion? the direction an ion would tend to diffuse based on the membrane potential the difference between the inside and outside concentrations of that ion the sum of the electrical and concentration gradients for that ion
the sum of the electrical and concentration gradients for that ion
As you start working out, you notice that your heart rate and breathing rate start to increase. Which division of your nervous system is generating this response? Be as specific as possible. the somatic nervous system the sympathetic division of the autonomic nervous system the afferent division of the nervous system the parasympathetic division of the autonomic nervous system
the sympathetic division of the autonomic nervous system
During the relative refractory period of an action potential, a larger than normal stimulus is needed to cause another action potential. This is due to the fact that ________. the inactivation gates on voltage gated sodium ion channels are closed the voltage gated potassium ion channels remain open long enough to hyperpolarize the axon membrane the membrane is now impermeable to all ions
the voltage gated potassium ion channels remain open long enough to hyperpolarize the axon membrane
When calcium ions enter the synaptic terminal, the inside of the receiving neuron becomes more positive. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. they cause an action potential in the sending neuron.
they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron.
Which choice best characterizes K+K+ leakage channels? common transmembrane channels that are always open for any ion to move through in the presence of K+ K+transmembrane channels that use energy to allow the movement of K+K+ across the membrane chemically gated K+K+ channels that open and close according to the binding of other molecules transmembrane protein channels that are always open to allow K+K+ to cross the membrane without the additional input of energy
transmembrane protein channels that are always open to allow K+K+ to cross the membrane without the additional input of energy
Bundles of axons in the central nervous system are called tracts.
true
If the neuron membrane becomes more permeable to Na+, Na+ will transport across the membrane, causing the cell to depolarize.
true
the generation of an action potential in a neuron requires the presence what type of membrane channels? leakage channels voltage-gated channels chemically gated channels
voltage-gated channels
Immediately after an action potential has peaked, which of the following channels will open? voltage-gated calcium channels voltage-gated potassium channels voltage-gated sodium channels
voltage-gated potassium channels
