Mastering A&P Chapter 11
Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the plasma membranes of all cells because of the presence of what type of channel? a) ligand-gated channels b) leak channels c) sodium-potassium ATPases d) voltage-gated channels
b) leak channels
Binding of the neurotransmitter to its receptor causes the membrane to _____________. a) depolarize b) either depolarize or hyperpolarize c) hyperpolarize
b) either depolarize or hyperpolarize
The sensory, or afferent, division of he peripheral nervous system carries information from the brain and spinal cord to effector organs. a) true b) false
b) false
Loss of K ions from the cytosol will have the same effect as: a) gain of Na ions b) gain of Cl ions c) gain of K ions d) loss of Cl ions
b) gain of Cl ions
What channels open or close in response to physical distortion of the membrane surface, such as vibrations or pressure? a) voltage-gated b) mechanically-gated c) chemically-gated d) ligand-gated
b) mechanically-gated
If a neuron simultaneously receives a stimulus that results in local depolarization of 10 mV and a stimulus that results in a local hyperpolarization of 10 mV, the net effect would be: a) net depolarization b) no net change in membrane potential c) neurons can only receive one incoming stimulus at a time d) net hyperpolarization
b) no net change in membrane potential
During the repolarization of a neuron: a) sodium ions move out of the cell b) potassium ions move out of the cell c) potassium ions move into the cell d) sodium ions move into the cell
b) potassium ions move out of the cell
Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference? a) action potential b) resting membrane potential (RMP) c) threshold potential d) positive membrane potential
b) resting membrane potential (RMP)
Hyperpolarization results from ___________. a) slow closing of voltage-gated Na+ channels b) slow closing of voltage-gated K+ channels c) fast closing of voltage-gated K+ channels
b) slow closing of voltage-gated K+ channels
Why does the action potential only move away from the cell body? a) the flow of the sodium ions only goes in one direction - away from the cell body b) the areas that have had the action potential are refractory to a new action potential
b) the ares that have had the action potential are refractory to a new action potential
Why does regeneration of the action potential occur in one direction, rather than in two directions? a) the activation gates of voltage-gated Na+ channels close in the node, or segment, that has just depolarized b) the inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential c) the activation gates of voltage-gated K+ channels open in the node, or segment, that has just depolarized d) the inactivation gates of voltage-gated K+ channels close in the node, or segment, that has just fired an action potential
b) the inactivation gates of voltage-gated Na+ channels close int he node, or segment, that has just fired an action potential
Function of Microglial Cells
- act as phagocytes
Functions of Astrocytes
- anchor neurons and blood vessels - regulate the extracellular environment - facilitate the formation of the blood-brain barrier - repair damaged tissue
Functions of Ependymal Cells
- line cavities - cilia circulate fluid around brain and spinal cord - some secrete this fluid
Function of Oligodendrocytes
- myelinate certain axons in the CNS
Function of Schwann Cells
- myelinate certain axons in the PNS
Function of Satellite Cells
- surround and support cell bodies
Identify the sequence of events that occurs at a synapse. 1. An action potential arrives at the synaptic terminal 2. Vesicles containing neurotransmitter fuse with the plasma membrane of the sending neuron 3. Neurotransmitter molecules diffuse across the synaptic cleft 4. The neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, causing ion channels there to open 5. Calcium channels open, and calcium ions enter the synaptic terminal
1, 5, 2, 3, 4
Place the events involved in the propagation of an action potential in the correct order of occurrence from left to right. 1. Axon segment depolarized to threshold 2. Local current flows to axon segment 3. Influx of Na+ 4. Voltage-gated Na+ channels open 5. AP regenerated in adjacent axon segment
2, 1, 4, 3, 5
Place the events involved in generation of an action potential in the correct order of occurrence from left to right. 1. Na+ channels close, K+ channels open 2. Na+ influx, depolarization 3. Hyperpolarization, K+ channels close 4. Threshold stimulus, Na+ channels open 5. K+ efflux, repolarization
4, 2, 1, 5, 3
Order each of the following events so that they occur in the proper order with respect to the function of the channels, ion permeability, and changes in membrane potential. 1. Repolarization of the membrane 2. Depolarization of the membrane to +30 mV 3. K+ ion flow out of the neuron increases 4. Na+ ion flow into the neuron increases 5. Opening of voltage-gated Na+ channels
5, 4, 2, 3, 1
What type of conduction takes place in unmyelinated axons? a) saltatory conduction b) continuous conduction c) synaptic transmission d) electrical conduction
b) continuous conduction
For every ATP split into an ADP and a phosphate, the Na+/K+ pump moves __________ out of the cell and __________ into the cell. a) 3 Na+; 2 K+ b) 3 K+; 2 Na+ c) 2 Na+; 3 K+ d) 2 K+; 3 Na+
a) 3 Na+; 2 K+
Which of these ions triggers exocytosis of synaptic vesicles? a) Ca2+ b) Na+ c) K+ d) Cl-
a) Ca2+
Which of the following causes the hyperpolarization phase of an action potential? a) K+ outflow via voltage-gated potassium ion channels b) Na+ outflow via voltage-gated sodium ion channels c) K+ influx via voltage-gated potassium ion channels d) Na+ influx via voltage-gated sodium ion channels
a) K+ outflow via voltage-gated potassium ion channels
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 beofre being returned? a) acetylcholine b) glutamate
a) acetylcholine
How is an action potential propagated along in an axon? a) an influx of sodium ions from the current action potential depolarizes the adjacent area b) stimuli from the graded (local) potentials from the soma and dendrites depolarize the entire axon c) an efflux of potassium from the current action potential depolarizes the adjacent area
a) an influx of sodium ions from the current action potential depolarizes the adjacent area
Where in the neuron is an action potential initially generated? a) axon hillock b) soma and dendrites c) anywhere on the axon
a) axon hillock
During depolarization, which gradient(s) move(s) Na+ into the cell? a) both the electrical and chemical gradients b) only the chemical gradient c) only the electrical gradient d) Na+ does not move into the cell. Na+ moves out of the cell
a) both the electrical and chemical gradients
Branches that may occur along an axon are called: a) collaterals b) dendrites c) hillocks d) telodendria
a) collaterals
Determine the direction in which and electrical signal is carried in a typical multipolar neuron. a) dendrites, cell body, axon b) cell body, axon, dendrites c) dendrites, axon, cell body d) axon, cell body, dendrites
a) dendrites, cell body, axon
A series of measurements with a voltmeter show a neuron's membrane potential becoming more negative, from -70 mV to -85 mV. This neuron is experiencing a: a) hyperpolarization phase b) polarization phase c) repolarization phase d) depolarization phase
a) hyperpolarization phase
Batrachotoxin produced by certain species of frogs is a toxin that permanently opens voltage-gated Na ion channels. The results of exposure to batrachotoxin will be: a) inability to generate action potentinals b) increased frequency of action potentials c) no depolarization d) permanent hyperpolarization
a) inability to generate an action potential
What changes occur to the voltage-gated Na+ and K+ channels at the peak of depolarization? a) inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open b) activation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open c) inactivation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open d) activation gates of voltage-gated Na+ channels close, while inactivation gates of voltage-gated K+ channels open
a) inactivation gates of voltage-gated Na+ channels close, while activation gates of voltage-gated K+ channels open
What type of neuron is found within the CNS to perform the job of information processing? a) interneurons (association neurons) b) motor (efferent) neurons c) bipolar neurons d) sensory (afferent) neurons
a) interneurons (association neurons)
Postsynaptic potentials are: a) local potentials b) action potentials c) resting potentials d) chemical potentials
a) local potentials
In which type of axon will velocity of action potential conduction be the fastest? a) myelinated axons with the largest diameter b) unmyelinated axons of the shortest length c) unmyelinated axons with the largest diameter d) myelinated axons with the smallest diameters
a) myelinated axons with the largest diameter
Saltatory propagation occurs in _________ axons, in which action potentials __________. a) myelinated; move from one node of Ranvier to another b) unmyelinated; spread by depolarizing the adjacent region of the axon membran c) unmyelinated; move from one node of Ranvier to another d) myelinated; move continuously along the axon toward the axon hillock
a) myelinated; move from one node of Ranvier to another
Which of the following is an effect of myelination? a) myelination increases the speed of conduction of action potentials b) myelination increases the volume of cerebrospinal fluid in circulation c) myelination increases the rate of mitosis in damaged neurons d) myelination increases the rate at which phagocytosis occurs in the brain
a) myelination increases the speed of conduction of action potentials
In a synapse, neurotransmitters are stored in vesicles located in the ____________. a) presynaptic neuron b) postsynaptic neuron c) synaptic cleft
a) presynaptic neuron
The type of action potential propagation in which action potentials are only generated at nodes of Ranvier is called ___________. a) saltatory conduction b) synaptic transmission c) unmyelinated conduction d) continuous conduction
a) saltatory conduction
Sarah sensed a mosquito land on her arm and swatted it away with her hand. Which specific PNS division was responsible for the movement of Sarah's hand? a) somatic motor division b) visceral sensory division c) somatic sensory division d) autonomic nervous system
a) somatic motor division
Upon entering your house, you noticed the smell of cake baking in the oven. What division of the peripheral nervous system is responsible? a) somatic sensory division b) somatic motor division c) visceral motor division d) visceral sensory division
a) somatic sensory division
What is the function of the myelin sheath? a) the myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals b) the myelin sheath decreases the speed of action potential conduction from the initial segment to the axon terminals c) the myelin sheath increases the insulation along the entire length of the axon d) the myelin sheath decreases the resistance of the axonal membrane to the flow of charge
a) the myelin sheath increases the speed of action potential conduction from the initial segment to the axon terminals
If a signal from a sending neuron makes the receiving neuron more negative inside, a) the receiving neuron is less likely to generate an action potential b) the receiving neuron is more likely to generate an action potential c) the receiving neuron immediately generates an action potential d) the sending neuron becomes more negative inside e) the sending neuron becomes more positive inside
a) the receiving neuron is less likely to generate an action potential
In the axon hillock, slow depolarization to threshold is due to ____________. a) the summation of EPSPs b) the opening of Na+ voltage-gated channels c) the opening of K+ voltage-gated channels d) the summation of IPSPs
a) the summation of EPSPs
The depolarization phase of an action potential results from the opening of which channels? a) voltage-gated Na+ channels b) chemically gated K+ channels c) voltage-gated K+ channels d) chemically gated Na+ channels
a) voltage-gated Na+ channels
what opens first in resonse to a threshold stimulus? a) voltage-gated Na+ channels b) ligand-gated cation channels c) ligand-gated Cl- channels d) voltage-gated K+ channels
a) voltage-gated Na+ channels
The generation of an action potential in a neuron requires the presence of what type of membrane channels? a) voltage-gated channels b) chemically gated channels c) leakage channels d) membrane channels are not required
a) voltage-gated channels
During the action potential, when does sodium permeability initially decrease? a) during repolarization b) during the peak of depolarization c) during hyperpolarization d) during the rising phase of depolarization
b) during the peak of depolarization
What is the value for the resting membrane potential for most neurons? a) +30 mV b) -70 mV c) -90 mV
b) -70 mV
The membranes of neurons at rest are very permeable to __________ but only slightly permeable to ___________. a) K+; Cl- b) K+; Na+ c) Na+; Cl- d) Na+; K+
b) K+; Na+
The concentrations of which two ions are highest outside the cell. a) Na+ and A- (negatively charged proteins) b) Na+ and Cl- c) K+ and A- (negatively charged proteins) d) K+ and Cl-
b) Na+ and Cl-
What prevents the Na+ and K+ gradients from dissipating? a) H+-K+ ATPase b) Na+-K+ ATPase c) Na+ and K+ leaks d) Na+ cotransporter
b) Na+-K+ ATPase
Which of the following membrane proteins is involved in active transport? a) Na+ leak channel b) Na+/K+ pump c) K+ leak channel d) Na+ voltage-gated channel
b) Na+/K+ pump
On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? a) the inside surface of the plasma membrane is much more positively charged than the outside surface b) the inside surface of the plasma membrane is much more negatively charged than the outside surface c) the outside surface of the plasma membrane is much more negatively charged than the inside surface d) there is no electrical potential difference between the inside and the outside surfaces of the plasma membrane
b) the inside surface of the plasma membrane is much more negatively charged than the outside surface
What characterizes depolarization, the first phase of the action potential? a) the membrane potential changes to a much more negative value b) the membrane potential changes from a negative value to a positive value c) the membrane potential reaches a threshold value and returns to the resting state d) the membrane potential changes to a less negative (but not a positive) value
b) the membrane potential changes from a negative value to a positive value
Which of the following is NOT one of the mechanisms for synaptic transmission termination? a) diffusion of neurotransmitter away b) uptake of neurotransmitter into postsynaptic neuron c) reuptake of neurotransmitter into presynaptic neuron d) degradation of neurotransmitter by enzyme
b) uptake of neurotransmitter into postsynaptic neuron
An action potential releases neurotransmitter from a neuron by opening which of the following channels? a) chemically gated Ca2+ channels b) voltage-gated Ca2+ channels c) voltage-gated K+ channels d) voltage-gated Na+ channels
b) voltage-gated Ca2+ channels
The channels that open when the axolemma reaches threshold depolarization are the: a) voltage-gated K ion channels b) voltage-gated Na ion channels c) chemically gated K ion channels d) chemically gated Na ion channels
b) voltage-gated Na ion channels
What is the magnitude (amplitude) of an action potential? a) 70 mV b) 30 mV c) 100 mV
c) 100 mV
During an action potential, hyperpolarization is caused by: a) K+ influx b) Na+ efflux c) K+ efflux d) Na+ influx
c) K+ efflux
The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped? a) K+ is pumped out of the cell and Na+ is pumped into the cell b) both Na+ and K+ are pumped into the cell c) Na+ is pumped out of the cell and K+ is pumped into the cell d) both Na+ and K+ are pumped out of the cell
c) Na+ is pumped out of the cell and K+ is pumped into the cell
Dark-staining clusters of RER and ribosomes in neurons are called ________. a) dendrites b) neurofibrils c) Nissl bodies d) nodes of Ranvier
c) Nissl bodies
The velocity of the action potential is fastest in which of the following axons? a) a large unmyelinated axon b) a small unmeylinated axon c) a small myelinated axon
c) a small myelinated axon
Which statement best describes the all-or-none principle? a) all neurons conduct an action potential together, or none do b) all voltage-gated sodium channels will open or none will open c) an action potential happens completely, or it doesn't happen at all d) local, or graded, potentials will always become action potentials
c) an action potential happens completely, or it doesn't happen at all
Involuntary control of smooth and cardiac muscles and glands is provided by the __________. a) visceral sensory division b) afferent division c) autonomic nervous system d) somatic motor division
c) autonomic nervous system
Which of the following are organs of the central nervous system? a) brain and cranial nerves b) spinal cord and spinal nerves c) brain and spinal cord d) brain, cranial nerves, spinal cord, and spinal nerves
c) brain and spinal cord
Bundles of axons known as tracts are part of the: a) ganglion b) myelin sheath c) central nervous system d) peripheral nervous system
c) central nervous system
The two anatomical divisions of the nervous system are the: a) sensory division and motor division b) somatic sensory division and visceral sensory system c) central nervous system and peripheral nervous system d) visceral motor division and somatic motor division
c) central nervous system and peripheral nervous system
Bidirectional, instantaneous synaptic transmission is typical of ___________. a) electrochemical synapses b) chemical synapses c) electrical synapses d) all synapses
c) electrical synapses
The relative refractory period is caused by: a) inactivation of voltage-gated Na ion channels b) depolarization to threshold c) hyperpolarization d) inactivation of voltage-gated K ion channels
c) hyperpolarization
If a drug inhibits the enzyme Acetylcholinesterase, the effect will be: a) decreased stimulation of ACh receptors b) increased ACh reuptake into presynaptic cell c) increased ACh availability in synaptic cleft d) increased levels of ACh inside synaptic vesicles
c) increased ACh availability in synaptic cleft
If the cytosol loses K+ ions through leak channels, it will become: a) less negative b) more positive c) more negative d) there will be no change in the membrane potential
c) more negative
What characterizes repolarization, the second phase of the action potential? a) as the membrane repolarizes to a negative value, it goes beyond the resting state to a value of -80 mV b) before the membrane has a chance to reach a positive voltage, it repolarizes to its negative resting value of approximately -70 mV c) once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV d) once the membrane depolarizes to a threshold value of approximately -55 mV, it repolarizes to its resting value of -70 mV
c) once the membrane depolarizes to a peak value of +30 mV, it repolarizes to its negative resting value of -70 mV
What event triggers the generation of an action potential? a) the membrane potential must hyperpolarize from the resting voltage of -70 mV to the more negative value of -80 mV b) the membrane potential must return to its resting value of -70 mV from the hyperpolarized value of -80 mV c) the membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of -55 mV d) the membrane potential must depolarize from the resting voltage of -70 mV to its peak value of +30 mV
c) the membrane potential must depolarize from the resting voltage of -70 mV to a threshold value of of -55 mV
The repolarization phase of an action potential results from ___________. a) the closing of voltage-gated K+ channels b) the closing of voltage-gated Na+ channels c) the opening of voltage-gated K+ channels d) the opening of voltage-gated Na+ channels
c) the opening of voltage-gated K+ channels
The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. a) the presence of concentration gradients and Na+-K+ pumps b) the presence of a resting membrane potential and leak channels c) the presence of concentration gradients and leak channels d) the presence of concentration gradients and voltage-gated channels
c) the presence of concentration gradients and leak channels
During an action potential, the rapid decrease in sodium permeability and simultaneous increase in potassium permeability is responsible for __________. a) the depolarization phase b) returning to the resting membrane potential after the action potential c) the repolarization phase d) the hyperpolarization phase
c) the repolarization phase
The plasma membrane is much more permeable to K+ than to Na+. Why? a) there are many more voltage-gated K+ channels than voltage-gated Na+ channels b) ligand-gated cation channels favor a greater influx of Na+ than K+ c) there are many more K+ leak channels than Na+ leak channels in the plasma membrane d) the Na+-K+ pumps transport more K+ into cells than Na+ out of cells
c) there are many more K+ leak channels than Na+ leak channels in the plasma membrane
Which of the following events will cause an EPSP? a) Ca ions exit the postsynaptic cell b) K ions exit postsynaptic cell c) Cl ions enter postsynaptic cell d) Na ions enter postsynaptic cell
d) Na ions enter postsynaptic cell
Depolarizing local potentials are caused by an influx of: a) Na ions via leak channels b) K ions via leak channels c) K ions via gated ion channels d) Na ions via gated ion channels
d) Na ions via gated ion channels
A bundle of axons in the PNS is called _______. a) a tract b) a spinal cord c) a ganglion d) a nerve
d) a nerve
Which nervous system division is responsible for the integration of sensory information? a) visceral motor division b) peripheral nervous system c) somatic motor division d) central nervous system
d) central nervous system
Binding of a neurotransmitter to its receptors opens ___________ channels on the ____________ membrane. a) chemically gated; presynaptic b) voltage-gated; postsynaptic c) voltage-gated; presynaptic d) chemically gated; postsynaptic
d) chemically gated; postsynaptic
Ependymal cells: a) form myelin in the brain and spinal cord b) help form the blood-brain barrier c) serve as wandering phagocytes during brain injury d) circulate cerebrospinal fluid
d) circulate cerebrospinal fluid
Action potential propagation in unmyelinated axons happens via: a) saltatory conduction b) synaptic transmission c) local potentials d) continuous conduction
d) continuous conduction
Which of the following is one of the mechanisms for termination of synaptic transmission? a) storage of neurotransmitter in vesicles b) reuptake of neurotransmitter into the postsynaptic cell c) release of neurotransmitter into the synaptic cleft d) degradation of neurotransmitter by enzyme
d) degradation of neurotransmitter by enzyme
If a stimulus opens ligand-gated sodium ion channels, the neuron will ___________. a) remain at its resting membrane potential b) repolarize c) hyperpolarize d) depolarize
d) depolarize
An action potential is self-regenerating because _________. a) repolarizing currents established by the efflux of Na+ flow down the axon and trigger and action potential at the next segment b) repolarizing currents established by the efflux of K+ flow down the axon and trigger and action potential at eh next segment c) depolarizing currents established by the influx of K+ flow down the axon and trigger an action potential at the next segment d) depolarizing currents established by the influx of Na+ flow down the axon and trigger and action potential at the next segment
d) depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment
Depolarization to threshold during action potential propagation in axons is due to: a) diffusion of K ions up to the previous segment of the axon b) diffusion of K ions down to the next segment of the axon c) diffusion of Na ions up to the previous segment of the axon d) diffusion of Na ions down to the next segment of the axon
d) diffusion of Na ions down to the next segment of the axon
Where do most action potentials originate? a) axon terminal b) cell body c) Nodes of Ranvier d) initial segment
d) initial segment
Conduction speed will be fastest in a ____________. a) large unmyelinated axon b) small unmyelinated axon c) small myelinated axon d) large myelinated axon
d) large myelinated axon
A molecule that carries information across a synaptic cleft is a: a) receiving neuron b) synapse c) synaptic cleft d) neurotransmitter e) sending neuron
d) neurotransmitter
Which of the following is controlled by the somatic motor division? a) smooth muscle b) cardiac muscle c) glands d) skeletal muscle
d) skeletal muscle
When calcium ions enter the synaptic terminal, a) they cause an action potential in the sending neuron b) the inside of the receiving neuron becomes more negative c) the inside of the receiving neuron becomes more positive d) they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron e) neurotransmitter molecules are quickly removed from the synaptic cleft
d) they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron
What is the first change to occur in response to a threshold stimulus? a) voltage-gated Na+ channels change shape, and their inactivation gates close b) voltage-gated K+ channels change shape, and their activation gates open c) voltage-gated Ca2+ channels change shape, and their activation gates open d) voltage-gated Na+ channels change shape, and their activation gates open
d) voltage-gated Na+ channels change shape, and their activation gates open
Myelinated axons in the CNS are known as: a) dark matter b) internodes c) gray matter d) white matter
d) white matter
When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, a) vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron b) ion channels in the plasma membrane of the sending neuron open c) the receiving neuron becomes more positive inside d) the receiving neuron becomes more negative inside e) ion channels in the plasma membrane of the receiving neuron open
e) ion channels in the plasma membrane of the receiving neuron open
The small space between the sending neuron and the receiving neuron is the: a) vesicle b) synaptic terminal c) neurotransmitter d) calcium channel e) synaptic cleft
e) synaptic cleft
