WorksheetsPhysiology 1: Chương 5 : Sinh lý thần kinh
Total questions: 180
Worksheet time: 3hrs 0mins
Which of the following is / are functions of the human nervous system?
Receiving, storing, and processing information on the internal and external environments
Bringing about changes in physiology and / or behavior to ensure optimal functions of homeostatic mechanisms.
Secretion of hormones
Coordination of movement
All of the choices are correct.
Which is not true of myelin?
It is a fatty membranous sheath
It is formed by glial cells.
It influences the velocity of conduction of an electrical signal down an axon
It covers all parts of the neuron, including the axon, cell body, and dendrites.
Which of the following is not true about axon transport?
It refers to the passage of materials from the cell body of a neuron to the axon terminals
It refers to the passage of materials from axon terminals to the cell body of a neuron
It refers to the transport of materials from the inside to the outside across the axonal membrane.
It is especially important for maintaining the integrity of neurons with long axons
Which is FALSE about neurons?
A given neuron can be either a presynaptic neuron or a postsynaptic neuron
B. An individual neuron can receive information from multiple other neurons.
C. An individual neuron can transmit information to multiple other neurons.
D. A neuron can simultaneously release more than one type of neurotransmitter.
E. A neuron receives information on its axons and delivers it to other neurons through its dendrites.
A given neuron can be either a presynaptic neuron or a postsynaptic neuron
An individual neuron can receive information from multiple other neurons
An individual neuron can transmit information to multiple other neurons.
A neuron can simultaneously release more than one type of neurotransmitter
A neuron receives information on its axons and delivers it to other neurons through its dendrites
Which of the following is not true of glial cells?
They form the myelin for axons.
Neurons outnumber glial cells 10 to 1 in the nervous system
They deliver fuel molecules to neurons and remove the waste products of metabolism
They are important for the growth and development of the nervous system.
They regulate the composition of the extracellular fluid in the CNS.
The difference in electrical charge between two points:
Is called the potential difference between those points
Is called the diffusion potential between those points
Is called the current, and is expressed in the units of millimoles
Is the same for all ions
According to the equation expressed as Ohm's law, which of these would cause the greatest increase in current?
Doubling both voltage and resistance
Reducing both voltage and resistance by half
Doubling voltage and reducing resistance by half
Reducing voltage by half and doubling resistance
Quadrupling both voltage and resistance
Compartments A and B are separated by a membrane that is permeable to K+ but not to Na+ or Cl-. At time zero, a solution of KCl is poured into compartment A and an equally concentrated solution of NaCl is poured into compartment B. Which would be true once equilibrium is reached?
The concentration of Na+ in A will be higher than it was at time zero.
Diffusion of K+ from A to B will be greater than the diffusion of K+ from B to A.
There will be a potential difference across the membrane, with side B negative relative to side A
The electrical and diffusion potentials for K+ will be equal in magnitude and opposite in direction
The concentration of Cl- will be higher in B than it was at time zero
Which is TRUE about the resting membrane potential?
It requires very few ions to be distributed unevenly
It has the same value in all cells.
It is oriented so that the cell's interior is positive with respect to the extracellular fluid.
Only nerve and muscle cells have a potential difference across the membrane at rest
It is not altered by changing concentration gradients of permeating ions
Which is TRUE about typical, resting neurons?
The plasma membrane is most permeable to sodium ions
The concentration of sodium ion is greater inside the than outside
The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions.
The plasma membrane is completely impermeable to sodium ions
The plasma membrane is completely impermeable to potassium ions
1. The membrane potential of most neurons at rest is:
Equal to the equilibrium potential for potassium.
Equal to the equilibrium potential for sodium.
Slightly more negative than the equilibrium potential of potassium ion.
More positive than the equilibrium potential for potassium
More positive than the equilibrium potential for sodium.
The diffusion potential due to the concentration gradient for Na+ across a nerve cell membrane:
Favors its movement into the cell at the resting membrane potential.
Favors its movement out of the cell at the resting membrane potential
Is equal and opposite to the electrical potential acting on Na+ at the resting membrane potential.
Is in the same direction as the diffusion potential due to the concentration gradient for K+
Favors movement of Na+ in the opposite direction as the electrical potential acting on Na+ at the resting membrane potential
Which would result from an increase in the extracellular concentration of K+ above normal?
Depolarization of resting nerve cells
Hyperpolarization of resting nerve cells
The potassium equilibrium potential of nerve cells would become more negative
The sodium equilibrium potential would become less positive
Which is TRUE about the Na+ / K+ - ATPase pump in neurons?
It generates a small electrical potential such that the inside is made negative with respect to the outside.
It maintains a concentration gradient for K+ such that diffusion forces favor movement of K+ into the cell
It maintains an electrical gradient at the equilibrium potential of K+
It transports equal numbers of sodium and potassium ions with each pump cycle
It pumps 3 Na+ ions into the cell for every 2 K+ ions it pumps out
Which of these would occur if the concentration of ATP were depleted in a typical nerve cell?
Resting membrane potential would become more negative
Resting membrane potential would become less negative
The concentration gradient for Na+ would remain the same.
The resting membrane potential would eventually become positive inside with respect to outside.
There would be no change in the resting membrane potential.
1. Which is FALSE about the equilibrium potential of a given ion across a membrane?
It is a function of concentration of that ion on both sides of the membrane.
It is the potential at which there is no net movement of that ion across the membrane
It is the potential difference across the membrane at which an electric force favoring movement of the ion in one direction is equal in magnitude and opposite in direction to the diffusion force provided by the concentration difference of the ion across the membrane.
A permeable ion will move in the direction that will tend to bring the membrane potential toward that ion’s equilibrium potential.
An anion that is in higher concentration inside the cell than outside the cell will have a negative equilibrium potential.
The equilibrium potential of K+ ions in nerve cells is about -90 mV. The membrane potential of typical nerve cells at rest is -70 mV. Therefore,:
Increasing the permeability of a resting neuronal membrane to K+ will make the membrane potential more negative inside with respect to outside.
In resting neurons, there is a net diffusion of K+ into the cell.
Changing the resting membrane potential of a neuron to -80 mV would increase K+ diffusion rate out of the cell
Potassium is the only permanent ion at rest.
There must be another permanent ion with an equilibrium potential more negative than -90 mV.
Which of the following statements concerning the permeability of a typical neuron membrane at rest is TRUE?
The permeability to Na+ is much greater than the permeability to K+
All of the K+ channels in the membrane are open
The voltage – gated Na+ channels are in the inactivated state.
Most of the voltage – gated Na+ channels are in the closed state.
There is equal permeability to Na+ and K+.
Which is NOT an example of a graded potential?
A receptor potential in a sensory receptor cell
A depolarizing excitatory postsynaptic potential (EPSP)
A hyperpolarizing inhibitory postsynaptic potential (IPSP)
A depolarizing pacemaker potential
A depolarizing action potential
An action potential in a neuronal membrane differs from a graded potential in that:
An action potential requires the opening of Ca2+ channels, whereas a graded potential does not
An action potential is propagated without decrement, whereas a graded potential decrements with distance.
An action potential has a threshold, whereas a graded potential is an all – or – none phenomenon.
Movement of Na+ and K+ across cell membranes mediate action potentials, while graded potentials do not involve movement of Na+ and K+.
Action potentials vary in size with the size of a thalamus, while graded potentials do not
A threshold stimulus applied to an excitable membrane is one that is just sufficient to:
Trigger an excitatory postsynaptic potential.
Cause a change in membrane potential
Trigger an action potential.
Be conducted to the axon hillock.
Depolarize a dendrite.
Which must happen in order for an action potential to begin?
The membrane potential must be at the Na+ equilibrium potential.
Na+ influx must exceed K+ efflux
The membrane must be out of the relative refractory period.
Na+ channels must all be inactivated.
Multiple inhibitory postsynaptic potentials (IPSPs) must summate.
Which describes the response of the voltage – gated channels when an axon is stimulated to threshold?
K+ channels open before the Na+ channels.
Na+ channels are activated and then inactivated.
K+ channels open at the same time as the Na+ channels.
K+ channels are opened when Na+ binds to the channel
K+ influx causes Na+ channels to inactivate.
During the rising (depolarizing) phase of a neuronal action potential:
. PK+ becomes much greater than PNa+.
PNa+ becomes much greater than PK+.
PK+ is the same as PNa+
Na+ efflux (flow out of the cell) occurs
K+ flows rapidly into the cell
Which is TRUE about neuronal membrane electrical and concentration gradients at the peak of the action potential?
The electrical gradient is in a direction that would tend to move K+ out of the cell
The concentration gradient for K+ is a direction that would tend to move it into the cell
The concentration gradient for K+ greatly increases compared to at rest.
The concentration gradient for Na+ is in a direction that would tend to move it out of the cell.
The electrical gradient for Na+ is in a direction that would tend to move it into the cell
Which is most directly responsible for the falling (repolarizing) phase of the action potential?
Voltage – gated Na+ channels are opened.
The Na+ / K+ pump restores the ions to their original locations inside and outside of the cell.
The permeabiltiy to Na+ increases greatly.
ATPase destroys the energy supply that was maintaining the action potential at its peak.
The permeability to K+ increases greatly while that to Na+ decreases.
Why are action potentials sometimes described as being "all-or-none" in character?
The rate of propagation of an action potential down an axon is independent of stimulus strength
They are associated with an absolute refractory period
A supra-threshold stimulus is required to stimulate an action potential during the relative refractory period.
An action potential occurs whenever a suprathreshold stimulus occurs, and its amplitude does not vary with the size of a stimulus.
Action potentials are always the same size, even when ion gradients vary in size
Which of the following statements about the phases of a neuronal action potential is TRUE ?
During the after-hyperpolarization phase, the permeability of the membrane to sodium ions is greater
than its permeability to potassium ions.
During the after-hyperpolarization phase, the permeability of the membrane to potassium ions is greater than its permeability at rest.
During the repolarizing phase, the permeability of the membrane to sodium ions is greater than its permeability to potassium ions
Potassium channels inactivate during the depolarization phase.
Repolarizing to negative membrane potentials causes the sodium channels to inactivate.
Which of the following statements about the refractory period of a membrane is TRUE?
The absolute refractory period refers to the period of time during which another action potential cannot be initiated in that part of the membrane that is undergoing an action potential, no matter how great the strength of the stimulus.
The relative refractory period refers to the period of time during which another action potential can be initiated in that part of the membrane that has just undergone an action potential if a stronger than normal stimulus is applied.
The refractory period prevents the action potential from spreading back over the part of the membrane that just underwent an action potential
The refractory period places an upper limit on the frequency with which a nerve cell can conduct action potentials.
All of the above choices are correct.
The relative refractory period of an axon coincides with the period of:
Activation and inactivation of voltage – dependent Na+ channels
Na+ permeability that is greater than that during the depolarization phase.
Increased K+ flux into the cell.
Increased K+ permeability of the cell.
Increased Na+ flux through K+ channels.
Neuronal axons typically have abundant:
Voltage – gated channels for Na+ that open in response to depolarization.
Voltage – gated channels for K+ that open in response to hyperpolarization.
Receptor – mediated channels for Na+.
Receptor – mediated channels for K+.
Voltage – gated channels for Ca2+
Which of the following statements regarding action potentials generated in a neuronal membrane is NOT TRUE?
Action potentials travel decrementally down the membrane
An action potential generates a new action potential in an adjacent area of membrane
An action potential generates a local current that depolarizes adjacent membrane to threshold potential
Action potentials are usually initiated at the initial segment of a neuron.
An action potential generated by a threshold stimulus is the same size as one generated by a suprathreshold stimulus.
Which of the following statements concerning the properties of action potentials is TRUE?
The rate of propagation of action potential down an axon is independent of stimulus strength
Action potentials can undergo summation.
A suprathreshold stimulus can stimulate an action potential during the absolute refractory period.
Action potentials generally propagate from the axon terminal toward the initial segment.
Increasing the size of a stimulus will increase the amplitude of an action potential.
How is the strength of a stimulus encoded by neurons?
By the size of action potentials
By the frequency of action potentials
By the duration of action potentials
By whether the action potential peak is positive or negative.
Which of the following statements concerning the rate of action potential propagation is TRUE?
It is faster in small-diameter axons than in large-diameter axons.
It is faster for a strong stimulus than for a weak one.
It is faster in myelinated axons than in nonmyelinated axons
It is faster in the dendrites than in the axon.
It occurs at the same rate in all axons, regardless of their diameter.
An action potential does not re-stimulate the adjacent membrane that was previously depolarized because
Stimulation is inhibited by the myelin sheath.
It is impossible for an action potential to be propagated along an axon toward the nerve cell body.
The resting membrane potential of the axon is too positive
The resting membrane potential of the axon is too negative.
That area of the membrane is in the absolutely refractory period.
The regions of axon membrane that lie between regions of myelin are the:
Islets of Langerhans.
Nodes of Ranvier.
Synaptic membranes.
Glial cells
Dens of iniquities.
Which is FALSE about interneurons?
They receive synaptic input from other neurons in the CNS
They sum excitatory and inhibitory synaptic inputs.
They deliver synaptic input on other neurons
They make synapses on effector organs in the PNS
They can transmit information between afferent neurons and efferent neurons.
Exocytosis of neurotransmitter into the synaptic cleft is triggered by an influx of ____________ in response to the arrival of an action potential in the axon terminal.
K+.
Na+
Ca2+
ATP.
Cl-
The main role of calcium ions at chemical synapses is to:
Depolarize the axon terminal of the presynaptic cell.
Bind to neurotransmitter receptors on the postsynaptic cell.
Cause fusion of synaptic vesicles with the plasma membrane of the axon terminal
Interfere with IPSPs in the postsynaptic cell
Diffuse across the synaptic space and enter the postsynaptic cell.
At an excitatory chemical synapse between two neurons:
There is increased permeability of a postsynaptic cell to both Na+ and K+
A small hyperpolarization of the postsynaptic membrane occurs when the synapse is activated.
An action potential in the presynaptic neuron always causes an action potential in the postsynaptic neuron
Excitation occurs because K+ enters the postsynaptic cell.
Action potentials spread through gap junctions between cells.
An inhibitory postsynaptic potential:
Is produced by simultaneous increases in permeability to both Na+ and K+
Occurs when a ligand – gated ion channel increases its permeability to K+.
Is a small depolarization in a postsynaptic cell
Can be summed with other IPSPs to trigger an action potential in the postsynaptic cell.
Is produced by an increase in permeability to only Na+.
Which of the following statements about EPSPs is FALSE?
They are produced by the opening of chemically – gated sodium channels
They transmit signals over relatively short distances.
They depolarize postsynaptic cell membranes.
They are able to summate.
They are always the same amplitude.
1. An EPSP:
Is a direct result of the opening of ligand – gated channels permeable to both Na+ and K+ ions.
Is a direct result of the opening of voltage – gated channels permeable to both Na+ and K+ ions.
Stabilizes the membrane to remain at its resting potential.
Opens voltage – gated Ca2+ channels in the presynaptic membrane
Occurs when voltage – gated Cl- channels open in a postsynaptic cell membrane.
Which best describes temporal summation?
A synapse is stimulated a second time before the effect of a first stimulus at the synapse has terminated.
It only refers to addition of EPSPs.
Two synapses on different regions of a cell are stimulated at the same time
It always brings a postsynaptic cell to threshold
The size of an EPSP depends on the size of the stimulus.
A postsynaptic neuron has three presysnaptic inputs – from neurons X, Y, and Z. Stimulation of neuron X causes the postsynaptic neuron to depolarize by 0.5 mV. When X and Y are stimulated simultaneously, the postsynaptic neuron depolarizes by 1 mV. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. What is most likely TRUE about presynaptic neurons Y and Z?
They are both excitatory
They are both inhibitory.
Y is excitatory and Z is inhibitory.
Z is excitatory and Y is inhibitory
A postsynaptic neuron has three presynaptic inputs – from neurons X, Y, and Z. When X and Y are stimulated simultaneously and repeatedly, the postsynaptic neuron reaches threshold and undergoes an action potential. When X and Z are stimulated simultaneously, however, there is no change in the membrane potential of the postsynaptic neuron. The simultaneous stimulation of X and Y is an example of:
Temporal summation.
Presynaptic inhibition.
Spatial summation.
Neuronal divergence.
Presynaptic facilitation
Which is TRUE about the initial segment of an axon ?
Its threshold potential is more positive than that of the cell body and dendrites
Its threshold potential is more negative than that of the cell body and dendrites.
Synapses far from the initial segment are more effective in influencing whether an action potential will be generated in the axon than are synapses close to the initial segment.
It is the region where neurotransmitter vesicles are docked and ready to be released by exocytosis.
It can only conduct graded potentials because it lacks voltage – gated Na+ channels
A presynaptic synapse:
Is a synapse between an axon terminal and a dendrite that can be either excitatory or inhibitory.
Is a synapse between an axon terminal and another axon’s terminal that can be either excitatory or inhibitory.
Is any synapse onto a cell body, and they can be either stimulatory or inhibitory.
Is a synapse between an axon terminal and a dendrite of the same cell, which is always inhibitory
Is a synapse between an axon terminal and another axon terminal that is always inhibitory.
Neuron X makes inhibitory axon – axon synaptic contact with neuron Y at the synapse of Y and neuron Z. Which will occur when action potentials are stimulated in neuron X?
Neuron Y will be inhibited from reaching the threshold to fire an action potential.
The release of neurotransmitter by neuron Y will be inhibited
The synapse between neurons Y and Z will be changed from an excitatory synapse to an inhibitory one.
Neurons Y and Z will both be more likely to reach threshold and fire an action potential.
Neurons Y and Z will be less likely to reach threshold and fire an action potential.
Which of the following is not known to be an important neurotransmitter in the CNS?
Dopamine
Acetylcholine.
Morphine
Glutamate.
Substance P
Which of the following statements about acetylcholine is correct ?
Acetylcholine binds to nicotinic and muscarinic receptors
Acetylcholine binds to adrenergic receptors.
Acetylcholine synthesis is catalyzed by acetylcholinesterase
Acetylcholine is the neurotransmitter released by most sympathetic postganglionic neurons
Acetylcholine is generally transported back into presynaptic nerve terminals without being enzymatically degraded.
Which of the following statements regarding neurotransmitters is TRUE?
Acetylcholine is broken down by enzymes present on postsynaptic cell membranes
Acetylcholine that is released at synapses bind to adrenergic receptors in the postsynaptic cell membrane
Catecholamines are the most abundant neurotransmitters in the central nervous system.
Opiate drugs, such as morphine, are antagonists of a class of neurotransmitters called endorphins
Gamma – aminobutyric acid (GABA) is a major excitatory transmitter in the central nervous system
Acetylcholine is the main neurotransmitter released by:
Preganglionic sympathetic neurons and cells of the adrenal medulla.
Cells of the adrenal medulla and postganglionic parasympathetic neurons.
Motor neurons and postganglionic sympathetic neurons.
Preganglionic sympathetic neurons and postganglionic sympathetic neurons
Preganglionic sympathetic neurons and motor neurons.
Which of the following statements about norepinephrine is FALSE?
Norepinephrine is a neurotransmitter
Norepinephrine binds to adrenergic receptors
Norepinephrine is a catecholamine.
Dopamine is a precursor to norepinephrine.
Epinephrine is a precursor to norepinephrine.
Which of the following enzymes is important for the metabolism of catecholamines?
Tyrosine hydroxylase.
Acetylcholinesterase
Superoxide dismutase.
Hydrocortinase.
Adenyl cyclase.
Nicotine is:
A cholinergic antagonist.
A beta – adrenergic agonist.
A cholinergic agonist.
An alpha – adrenergic antagonist.
A neurotransmitter.
Serotonin:
Acts as a neuromodulator.
Is a catecholamine neurotransmitter.
Is a neuropeptide
Has an inhibitory effect on pathways that are involved in the control of muscles.
Has an excitatory effect on pathways that mediate sensations
Alzheimer’s disease is thought to involve primarily:
Loss of neurons that secrete or respond to catecholamines.
Loss of adrenergic neurons
Loss of cholinergic neurons.
Loss of neurons that secrete or respond to dopamine
Tumors that produce excess serotonin.
Which is one of the major inhibitory neurotransmitters in the CNS?
Glutamate
Dopamine
Norepinephrine
Gamma – aminobutyric acid (GABA).
Beta – endorphin.
Which is one of the most abundant excitatory neurotransmitters in the CNS?
Glutamate.
Dopamine
Norepinephrine
Gamma – aminobutyric acid (GABA).
Endorphin
The central nervous system includes the:
Afferent nerves and spinal cord.
Efferent nerves and spinal cord.
Autonomic nervous system and the brain
Brain stem and the autonomic nervous system
Brain and spinal cord
The portion of the peripheral nervous system that is composed of nerve fibers that innervate skeletal muscle is called the:
Afferent nervous system
Sympathetic nervous system
Parasympathetic nervous system
Somatic motor nervous system
Autonomic nervous system
The region of the brain that is the most important control area for homeostatic regulation of the internal environment is:
The thalamus
The hippocampus
The cerebrum
The cerebellum
The hypothalamus
Which of the following kinds of neurons is NOT generally cholinergic?
Somatic motor neurons.
Postganglionic sympathetic neurons
Postganglionic parasympathetic neurons.
Preganglionic sympathetic neurons.
Preganglionic parasympathetic neurons
Which of the following does NOT result from the binding of nicotine with nicotinic acetylcholine receptors ?
A mild form of skeletal muscle paralysis that creates a more relaxed state
Signal transmission at neuromuscular junction
Generation of excitatory signals within autonomic ganglia
The release of norepinephrine, dopamine, and epinephrine.
Facilitation of the release of multiple neurotransmitters within the brain, including the “reward pathway” involving dopamine.
Drug X interferes with the action of norepinephrine at synapses. Which of the following mechanisms would not explain the effects of X?
X inhibits synthesis of norepinephrine at the axon terminal
X inhibits norepinephrine release from the terminal.
X blocks reuptake of norepinephrine by the terminal.
X is an adrenergic receptor antagonist.
X stimulates the catabolism of norepinephrine.
Synthesis of neuropeptides differs from that of other neurotransmitters because it:
Takes place in the axon terminals of neurons.
Takes place in the cell bodies of neurons.
Takes place on ribosomes in the posynaptic cell’s membrane.
Uses amino acids as precursor molecules.
Only takes place at synapses outside the central nervous system.
Which best describes the reticular formation of the brain?
It is mainly involved in motor coordination and balance.
It is the master endocrine gland of the brain.
It is primarily responsible for visual perception.
It integrates information from all regions of the CNS, and incorporates the mechanisms that regulate sleep and wakefulness.
It is the primary synaptic relay station for sensory information entering the CNS
The cerebellum:
Is important for coordinating body movement.
Is the gray matter covering the entire surface of the brain
Is the same thing as the brain stem.
Is in the anterior portion of the brain, just above the eyes
Is one of the basal nuclei that is found deep inside the cerebrum.
The _____________ is best described as “an interconnected group of brain structures including parts of the frontal lobe – cortex, temporal lobe, thalamus, and hypothalamus, that is associated with learning, emotional experience, and behavior”?
Diencephalon
Cerebrum.
Limbic system
Reticular formation
Cerebellum.
Which is a FALSE statement about the cerebrospinal fluid?
It has the same composition as blood plasma.
It acts as a cushion for the brain and spinal cord.
It is secreted by cells lining the ventricles of the brain.
It circulates within and between brain ventricles and surrounds the spinal cord.
It is in diffusion equilibrium with the extracellular fluid of the central nervous system.
Which of the following is NOT characteristic of the sympathetic division of the ANS?
Preganglionic neurons tend to be long, with the ganglion located in or near the effector target tissue(s).
Preganglionic neurons are short and synapse in ganglia located near the spinal cord
Preganglionic neurons release acetylcholine at synapses with postganglionic neurons.
Postganglionic neurons release norepinephrine at their neuroeffector junctions.
Postganglionic neuron cell bodies are located in the collateral chain ganglia (sympathetic trunk).
Postganglionic neuron cell bodies of the autonomic nervous system have which category of neurotransmitter receptor?
Adrenergic receptor
Serotonin receptors
Muscarinic acetylcholine receptors
Nicotinic acetylcholine receptors.
Dopamine receptors.
Which of the following statements cocerning a neuron is NOT correct?
It is the basic unit of the nervous system.
It is a glial cell.
It generates electrical signals
It may communicate with other neurons via chemical signals.
1. Which of the following statements concerning axonal transport is NOT correct?
Uses microtubles.
Uses kinesin and dynein
Is capable of bidiretional traffic (retrograde & anterograde).
Transports transmitters from the cell body to the synaptic region.
It occurs in motor (efferent) neurons only.
Which of the following statements concerning glial cells is NOT correct?
Are less abundant than neurons
Respond to injury.
Help myelinate CNS axons.
A. Help regulate neuronal environment.
Which of the following statements concerning equilibrium potential of a given ion across a membrane is correct?
Is a function of the concentration of that ion on the extracellular side of the membrane.
Is a function of the concentration of that ion on the intracellular side of the membrane.
Is the potential at which there is no movement of that ion across the membrane due to electrochemical forces
Is the potential at which there is equal movement of that ion into and out of the cell across the membrane due to electrochemical forces.
Resting membrane potential is generated:
By the movement of K ions down their electrical gradient through leak channels.
By the opening of voltage – gated sodium channels.
By the action of the Na+ / K+ ATPase pump which transports positive ions in unequal numbers.
By the movement of Na ions against their concentration gradient through leaked channels.
During an action potential:
Ligand – gated K channel in the membrane open in response to depolarization.
Voltage – gated sodium channels in the membrane open in response to neurotransmitter released from adjacent membrane
The increase in sodium permeability in the membrane is an example of positive feedback.
The movement of Na into the neuron causes the cell to hyperpolarized.
Threshold stimuli are those that are strong enough to:
Repolarize the neuron membrane.
Cause a net flux of positively charged ions from inside to outside the cell
Cause a net flux of positively charged ions from outside to inside the cell.
Close potassium channels to the point that an action potential is initiated.
Open potassium channels to the point that an action potential is initiated.
Which of the following statements concerning the absolute refractory period is correct?
Potassium channels are open and the membrane is hyperpolarized.
It immediately follows the relative refractory period.
It allows an action potential to proceed in two directions along the length of an axon.
It occurs when the sodium channels are open
Which of the following statements concerning the propagation of action potentials is NOT correct?
Saltatory conduction occurs in myelinated nerve fibers
During conduction of an action potential, current flows from the active area of the membrane to the adjacent inactive area, thereby decreasing the potential in the inactive area to threshold
Action potential propagation is faster in myelinated fibers than in unmyelinated ones.
Action potential propagation is faster in large – diameter fibers than in small – diameter ones.
Action potential propagation is faster for strong stimuli than for weaker stimuli.
Neurotransmitters are removed from the synaptic cleft by:
Active transport into the postsynaptic axon terminal, a process called reuptake.
Enzymatic transformation into inactive substances.
Diffusion into the synaptic cleft.
Permanent binding to the receptors.
Many important proteins have been recently recognized to function in various synaptic processes. Which of the following proteins are associated with the synaptic vesicles and release of neurotransmitter?
SNARE proteins and synaptotagmin
Dynein and kinesin.
Tubulin.
SNARE proteins, synaptotagmin and tubulin
Dynein, kinesin, and tubulin.
Which of the following statements concerning postsynaptic potential is NOT correct?
Directly result from the opening of voltage – gated ion channels
May be depolarizing or hyperpolarizing
May be summed
Is a graded potential.
An EPSP is:
A type of graded potential
Caused by an increase in the permeability of the postsynaptic membrane to all small ions
A hyperpolarizing potential
Sufficient by itself to generate an action potential.
All – or – none in character
An IPSP:
Is depolarizing.
Is caused by an increase in the permeability of the postsynaptic membrane to potassium or chloride ions
Is caused by an increased in the permeability of the postsynaptic membrane to sodium ions.
Is caused by an increase in the permeability of the postsynaptic membrane to all small ions.
Cannot be summed
Which of the following statements concerning neuromodulators is NOT correct?
They modify the postsynaptic neuron’s response to a specific neurotransmitter.
They may change the presynaptic neuron’s synthesis of a neurotransmitter
They may change the presynaptic neuron’s release of a transmitter.
They may be released by the presynaptic neuron along with the neurotransmitter
Their actions are faster than neurotransmitters.
Which brain disease involves degeneration of cholinergic neurons in certain brain regions, causing deterioration of cognitive and intellectual functions in the elderly?
Schizophrenia
Depression
Alzheimer disease
Cerebral Palsy
Parkinson disease.
Low levels of the neuromodulator, serotonin, is often associated with:
Depression
Multiple sclerosis.
Alzheimer disease
Parkinson disease
Cerebellar disease
In the biosynthesis of catecholamines,
The rate – limiting step is the conservation of L – Dopa to dopamine
The rate – limiting step is the conservation of tyrosine to dopamine.
The rate – limiting step is catalyzed by the enzyme tyrosine hydroxylase.
Epinephrine is converted to norepinephrine.
Which of the following is NOT associated with the CNS neurotransmitter, glutamate?
AMPA receptors
NMDA receptors.
Generation of IPSPs.
Long – term potentiation
Which of the following CNS neurotransmitters produce an IPSP?
Glutamate.
GABA (gamma – amino – butyric acid).
Glycine.
Glutamate and glycine.
GABA (gamma – amino – butyric acid) and glycine.
Which of the following neurotransmitter: drug combinations is mismatched?
Acetylcholine: atropine.
GABA: valium
Opioids: morphine.
Serotonin: codeine.
The cerebral cortex:
Is part of the hindbrain
Is the thin outer coat of white matter found on both the right and left cerebral hemispheres
Recieves input from the thalamus, brainstem and other regions of cortex
Contains cerebrospinal fluid
The motor part of the autonomic nervous system:
Contains afferent fibers.
Contains pre- and postganglionic fibers
Contains only parasympathetic components
Provides efferent innervation of skeletal muscle
The somatic motor portion of the peripheral nervous system:
Contains afferent fibers.
Has cell bodies located in the brainstem only.
Has large diameter, myelinated axons.
Use norepinephrine as its neurotransmitter.
Which of the following is generally NOT synthesized in most postganglionic sympathetic neurons?
L – Dopa.
Dopamine.
Norepinephrine.
Acetylcholine.
The blood brain barrier:
Functions to control the exchange of substances between blood and the extracellular fluid in the CNS
Is comprised of the cells that line the largest blood vessels in the brain
Is comprised of the cells that line the ventricles of the brain
Prevents diffusion of lipid soluble molecules from the blood to the brain.
A myelinated axon is shielded from direct contact with the extracellular fluid all along its length
(a)
The lipid portion of a cell's plasma membrane constitutes a barrier to current.
(a)
Ions other than Na+, K+, and Cl- play no role in generating the resting membrane potential of a cell
(a)
The maintenance of a resting potential in a neuron depends indirectly upon the functioning of the Na+ / K+ - ATPase pumps in the membrane
(a)
A graded potential in a membrane results in an electric current along an adjacent area of membrane and this current diminishes with distance from the site of the initial potential change.
(a)
During a hyperpolarizing graded potential, positively charged ions flow away from the site of the initial hyperpolarization on the outside of the membrane and toward this site on the inside.
(a)
Because so many Na ions move into a cell during an action potential and so many K ions move out, no further action potentials can be generated in a given membrane until the Na+ / K+ - ATPase pumps can restore the concentration gradient
(a)
The Na+ and K+ channels that open during an action potential are voltage regulated, both opening in response to depolarization of the membrane.
(a)
SNARE receptor protein complexes in presynaptic neurons function as inhibitors of calcium transport to
dampen or reduce the amount of neurotransmitter vesicles which participate in exocytosis.
(a)
The action potential elicited by a supra-threshold stimulus is larger than one elicited by a threshold stimulus.
(a)
The relative refractory period of an excitable membrane refers to the period of time during which no stimulus, however strong, will elicit a second action potential in the membrane.
(a)
The absolute refractory period of an excitable membrane roughly corresponds to the period when sodium channels are opening and inactivated.
(a)
Because all parts of a neuronal cell body have the same threshold, no one synapse on the cell is more important than any other.
(a)
The frequency of action potentials in a postsynaptic cell is directly related to the degree of depolarization of the postsynaptic cell.
(a)
Catecholamines are the most abundant neurotransmitters in the CNS.
(a)
Opioid drugs, such as morphine, are agonists of a class of neurotransmitters called endorphins.
(a)
The most common neurotransmitters for neuroeffector communication are dopamine and acetylcholine.
(a)
Dorsal root ganglia contain the cell bodies of efferent neurons.
(a)
Spinal nerves are composed of the axons of both afferent and efferent neurons.
(a)
Although nerve cells in each cerebral hemisphere make connections with other cells in the same hemisphere, there is no crossover of information between the two hemispheres.
(a)
The cerebrum consists only of gray matter.
(a)
The basal ganglia are important subcortical nuclei in the cerebrum.
(a)
The thalamus is the single most important control area for regulating the homeostasis of the internal environment.
(a)
The efferent division of the peripheral nervous system consists of the somatic nervous system and the autonomic nervous system.
(a)
Preganglionic fibers of the parasympathetic division of the autonomic nervous system leave the CNS at the level of the brainstem and sacral portions of the spinal cord
(a)
Most of the parasympathetic ganglia lie in chains along the spinal cord called sympathetic trunks.
(a)
Responses made possible by motor signals transmitted by the parasympathetic nervous system tend to be
displayed throughout the body simultaneously because there is much divergence of nerve pathways and
close anatomical association between presynaptic neurons and their ganglia as well as accessory activity
with the adrenal glands.
(a)
The sympathetic division of the autonomic nervous system is arranged so that it acts largely as a unit, whereas the components of the parasympathetic division generally act as discreet, independent
components.
(a)
"Dual innervation of effectors" refers to the innervation of the same effector organs by somatic and autonomic nerves.
(a)
Neurotransmitters are all small sized organic molecules such as acetylcholine and norepinephrine
(a)
All the neurotransmitters that have been discovered are soluble. Gaseous neurotransmitters are not known
(a)
The hypothalamus is made up of cell groups deep in the midbrain and is associated with posture and balance
(a)
In the parasympathetic division of the autonomic nervous system, acetylcholine is the major neurotransmitter released between the pre- and postganglionic fibers
(a)
If resistance is high, the current flow is high
(a)
Lipids are a barrier to current
(a)
Na+ flux has more impact on the resting membrane potential than does K+ flux
(a)
Membrane potential is due purely on directly to the passive movement of ions down the concentration gradients
(a)
A presynaptic terminal does not release a constant amount of neurotransmitter every time it is activated
(a)
Neuromodulators often modify the presynaptic cell’s response to specific neurotransmitters, amplifying or dampening the effectiveness of ongoing synaptic activity
(a)
Neuromodulators ultimately alter the effectiveness of the synapse including the synthesis, release, reuptake, or metabolism of a transmitter.
(a)
After ACh, is released and activates receptors on the postsynaptic membrane, the concentration of ACh at the postsynaptic membrane decreased by the enzyme acetylcholinesterase, this enzyme is located on the presynaptic and postsynaptic membranes.
(a)
Although a receptor is considered specific for a given ligand, such as ACh, most receptors will recognize natural or synthetic compounds that exhibit some degree of chemical similarity to that ligand
(a)
The nicotinic acetylcholine receptor does not contain an ion channel and is not permeable to both Na and K ions; plays a major role in attention, learning and memory
(a)
Catecholamines play esstential roles in states of consciousness, mood, motivation, directed attention movement, BP regulation, and hormone release
(a)
All catecholamine receptors are metabotropic, and thus use second messengers to transfer a signal from the surface of the cell to the cytoplasm
(a)
β – adrenoceptors act via stimulatory G proteins to decrease cAMP in the postsynaptic cell.
(a)
α – adrenoceptors exist in 3 subclasses, and they presynaptically inhibit norepinephrine releases or post synaptically to either stimulate or inhibit the activity of different types of K+ channels
(a)
90% of the body’s total serotonin is found in the digestive system, 8% in the blood platelets and immune cells, and only 1 – 2% is found in the brain
(a)
Amino acid neurotransmitters are the most prevalent neurotransmitters in the CNS
(a)
Postsynaptically, GABA may bind to ionotropic or metabotropic receptors. Ionotropic receptor as many other binding sites, i.e; steroids, barbiturates, and benzodiazepines
(a)
Ethanol inhibits GABA synapses and simultaneously simulates excitatory glutamate synapses, with the overall effect being global depression of the electrical activity of the brain
(a)
Glycine binds to metabotropic receptors on postsynaptic cells that allow Cl- to enter, thus preventing them form approaching the threshold for firing action potentials
(a)
Neuropeptides are cosecreted with another type of neurotransmitter and act as neuromodulators.
(a)
Neuropeptides can diffuse away from the synapse and affect other neurons at some distance, in which case they are called neuromodulators
(a)
Opiate drugs are powerful analgesics, meaning they relieve pain without loss of consciousness.
(a)
Purines such as ATP and adenosine act principally as neurotransmitters
(a)
Nonpyramidal cells are mostly involved in receiving inputs into the cortex and in local processing of information.
(a)
The cerebral cortex is one of the most complex integrating areas of the nervous system but does not have control over the system that govern the movement of the skeletal muscles
(a)
In the spinal cord, gray matter is surrounded by white matter, which consists of groups of myelinated axons. These groups of fiber tracts run longitudinally through the cord, some descending to relay information from the brain to the spinal cord and others ascending to transmit information to the brain
(a)
Neurons of the somatic division innervate cardiac and smooth muscle, whereas autonomic innervate skeletal muscles.
(a)
Major of ACh receptors in the autonomic ganglia are nicotinic receptors. In contrast, the ACh receptors on cellular targets of postganglionic autonomic neurons are muscarinic receptors. The cholinergic receptors on skeletal muscle fibers, innervated by the somatic motor neurons, not autonomic neurons, are nicotinic receptors.
(a)
Upon activation, the adrenal medulla release a mixture of 20% epinephrine and 80% norepinephrine into the blood.
(a)
You are studying a cross-sectional tissue slice of a nerve using a transmission electron microscope. You find an area where there appears to be a small amount of cytoplasm surrounded by about 100 layers of stacked cell membranes. You conclude that you have found
Neuron cell body
A synapse
An unmyelinated axon
A myelinated axon
Some viruses can hide from the immune system by retrograde transport from axonal terminals in the skin to the cell body of a neuron. Which of the following might be an effective preventative therapy?
A kinesin inhibitor
A dynein inhibitor
Actin polymerization inhibitor
Myosin inhibitor
None of these would prevent this type of infection
If there was an increased concentration of K+ outside of the neuron, which would be TRUE?
Neurons would spontaneously depolarize
Neurons would spontaneously hyperpolarize
The potassium equilibrium potential of nerve cells would become more negative
The sodium equilibrium potential would become less positive
During an action potential, the neuron would repolarize slowly or stay depolarized
Two neighboring neurons are at rest. Neuron A has a resting membrane potential of -80mV, Neuron B has a resting membrane potential of -70mV. Which is likely to be TRUE?
Neuron A has more K+ channels open than Neuron B
Neuron B has more K+ channels open than Neuron A
Neuron A has more Na+ channels open than Neuron B.
Neuron B has more Na+ channels open than Neuron A
None of the answer choices are correct
Using a micropipette, a neuroscientist injects an axon with enough Na+ ions to move the membrane potential +25mV (from resting). What happens next?
The membrane potential will be at the Na+ equilibrium potential
Voltage-gated Na+ will be triggered to open
The neuron membrane will be hyperpolarized
Na+ channels will all be inactivated
None of the answer choices are correct.
Procaine (Novocain) is a drug that blocks voltage-gated Na+ channels. When present, what would happen in a neuron?
Graded potentials are possible, but the neuron will not have the depolarizing phase of the action potential
Neither graded potentials nor action potentials will occur
Graded potentials are possible and the neuron will have the depolarizing phase of the action potential, but will be unable to repolarize
No phase of the action potential will be affected
Two stimuli occur on the same neuron more than a minute apart. The second stimulus is more than ten times greater than the first. If we compare the two resulting action potentials, which is TRUE?
The second stimulus will lead to an action potential with higher amplitude.
The second stimulus will lead to an action potential with a longer duration
The second stimulus will lead to an action potential with a longer hyperpolarization at the end.
The amplitude of the two action potentials will be the same.
The amplitude and duration of the second action potential will be greater than the first.
Visual signals travel on myelinated axons. While most pain signals travel on unmyelinated axons. If you get a paper cut, will you see the cut happen or feel the pain first?
Both sensations will occur at the same time
You will feel the pain sensation before the visual sensation
You will experience the visual sensation before the pain sensation
It depends on the magnitude of the pain sensation, it may reach the brain first or second
Inside a neuron, calcium binding sites are likely found on
Smooth endoplasmic reticulum
Kinesin proteins
Proteins associated with synaptic vesicles
Dyenin proteins
Lysosomal proteins
You are studying the role of a newly discovered neurotransmitter. You find that there are receptors for this neurotransmitter on interneurons in the brain and that when it binds, it causes the opening of K+ channels. What can we expect of the postsynaptic cells under influence of this neurostransmitter?
The postsynaptic cell will immediately undergo an action potential
The postsynaptic cell will undergo an IPSP
The postsynaptic cell will undergo an EPSP
There will be no change to the membrane potential in the postsynaptic cell
A postsynaptic neuron has an RMP of -70mV and a typical threshold of -55mV. It has three presynaptic inputs—from neurons X, Y, and Z. Stimulation of neuron X causes the postsynaptic neuron to depolarize by 0.5 mV. When X and Y are stimulated simultaneously, the postsynaptic neuron depolarizes by 1 mV. If X fires 10 times and Y fires 10 times the result will be
A subthreshold summation
Presynaptic inhibition
Threshold is reached and an AP is fired
Many APs are fired
The membrane depolarizes
Heroin causes similar, but much stronger effects to the nervous system as endogenous opioids. Heroin's mechanism of action might be that it acts as an:
Agonist to serotonin receptors
Agonist to the endogenous opioid receptors
Agonist to glycine receptors
Agonist to epinephrine receptors.
Any of these are possible
Nicotinic receptors are expressed on skeletal muscle cells. Which of the following would likely be a side-effect of the use of nicotine, an agonist for those receptors?
Muscle relaxation
Muscle cell twitches (contractions)
Muscle paralysis
Drowsiness
None of the answer choices are correct
Multiple sclerosis is a disease that primarily effects the somatic motor nervous system. Which of the following might be symptoms of multiple sclerosis?
Difficulty controlling muscle movements, such as using a fork and knife to cut food
Inappropriate sensory sensation, such as hearing voices when in a silent room
Difficulty expressing appropriate emotional responses
Cognitive and memory decline
Difficulty digesting foods due to inactivity of the muscles in the walls of abdominal organs
A genetic mutation that results in faulty SNARE receptor protein complexes would have only very mild effects on the nervous system
(a)
Drug Z is an agonist for a neurotransmitter receptor. It has a much higher affinity for the receptor and binds four times longer than the endogenous neurotransmitter. If you compare drug Z with the endogenous neurotransmitter, it's likely that drug Z will cause more frequent action potentials than the endogenous ligand
(a)
You have a patient who severed a spinal nerve in an accident. She will only lose sensory sensation, but all motor innervation to that area will remain intact
(a)
You pass by the office of a practitioner of alternative medicine. A poster hanging in the window offers therapies that result in "activation of the brainstem and sacral portions of the spinal cord." The poster is promoting methods that will result in enhanced activation of the parasympathetic nervous system.
(a)
