Exam 2
During the action potential, a second stimulus, no matter how strong, will not produce a second action potential because the membrane is in its _______ period.
absolute refractory
Chemical synapse
A location where neurotransmitter signals link the electrical activity of two cells.
graded potential
a potential change of variable amplitude and duration that is conducted decrementally; has no threshold or refractory period
Convergence
Multiple presynaptic neurons synapse on a single postsynaptic neuron.
Clearly explain why a myelinated axon has a more rapid conduction speed than an axon of the identically diameter that is unmyelinated (2 pts) THIS HAS A 2-part answer:
(i) the APS are only made in unmyelinated parts of the axon e.g. only the NODEs for a myelinated axon. (ii) In a myelinated axon, the Local current moving from end of one node to start of next node (i.e. thru a given myelinated section) is much faster time that if had to produce an entire sequences of APs to all along the membrane in the insulated (myelinated)section.
Electrical synapse
A location where gap junctions provide a low-resistance electrical connection between two cells.
Postsynaptic density
A location where neurotransmitter receptors are clustered.
Synaptic vesicles
A presynaptic location where neurotransmitter molecules are stored.
Divergence
A single presynaptic neuron branches to synapse on multiple postsynaptic neurons.
Which of the following statements about acetylcholine is correct? A. Acetylcholine binds to nicotinic and muscarinic receptors. B. Acetylcholine binds to adrenergic receptors. C. Acetylcholine synthesis is catalyzed by acetylcholinesterase D. Acetylcholine is released by all sympathetic postganglionic neurons. E. Acetylcholine is reuptaken into the presynaptic neuron terminal from the synaptic cleft.
A. Acetylcholine binds to nicotinic and muscarinic receptors.
Which is one of the most abundant excitatory neurotransmitters in the CNS? A. Glutamate B. Dopamine C. Norepinephrine D. Gamma-aminobutyric acid (GABA) E. Endorphin
A. Glutamate
Which is a FALSE statement about the cerebrospinal fluid? A. It has the same composition as blood plasma. B. It acts as a cushion for the brain and spinal cord. C. It is secreted by cells lining the ventricles of the brain. D. It circulates within and between brain ventricles and surrounds the spinal cord. E. It is in diffusion equilibrium with the extracellular fluid of the central nervous system.
A. It has the same composition as blood plasma.
Excitatory synapse
An event at this location brings a postsynaptic cell's membrane potential closer to threshold.
Inhibitory synapse
An event at this location can either stabilize or hyperpolarize a postsynaptic cell's membrane potential.
If an effector has adrenergic receptors, it will respond to norepinephrine/epinephrine. How can you make sense of what tissues are excited and what tissues are inhibited by norepi/epi?
Answer giving example of an organ/tissue excited by Norepi and a different organ/tissue that is inhibited by Norepi. Fright/Flight MORE sympathetic output --> ++ heart rate -- GI tract function LESS parasympathetic output "less brake on heart" Resting/Digesting LESS sympathetic output --> -- heart rate ++ GI tract function MORE parasympathetic output
Which of the following statements regarding neurotransmitters is TRUE? A. Acetylcholine released at synapses binds to adrenergic receptors on the postsynaptic cell B. Acetylcholine is broken down in the synaptic cleft by enzymes. C. Catecholamines are the most abundant neurotransmitters in the central nervous system. D. Gamma-aminobutyric acid (GABA) is a major excitatory transmitter in the central nervous system. E. Glutamate is a major inhibitory transmitter in the central nervous system.
B. Acetylcholine is broken down in the synaptic cleft by enzymes
Drug X interferes with the action of norepinephrine at synapses. Which of the following mechanisms would NOT explain the effects of X? A. X inhibits synthesis of norepinephrine at the axon terminal. B. X inhibits norepinephrine release from the terminal. C. X blocks reuptake of norepinephrine by the terminal. D. X is an adrenergic receptor antagonist. E. X stimulates the catabolism of norepinephrine.
C. X blocks reuptake of norepinephrine by the terminal.
What is it about voltage-gated Na+ ion channels and voltage-gated K+ ion channels that is responsible for unidirectional propagation of action potentials along the axon?
CHANNEL IS INACTIVATED (closed) at the end of the AP happening there on that section of the axonal membrane but the gating particles for Na+ and for K+ channels are NOT yet in their "at Rest" positions. (the inactivation gate is still blocking each channel, not the activation gate yet) . So, the ion channels in a section of the membrane that just experienced an AP cannot response to local currents that may be generated by new AP's happening in the next portion of the axon as those local currents move back "up" the axon to the "refractory" channels. (AT REST position shown in the left side -the "Closed" diagram; INACTIVATED position shown on right side)
In the _______, the _______ form myelin sheaths around multiple axons.
CNS; oligodendrocytes
Which is one of the major inhibitory neurotransmitters in the CNS? A. Glutamate B. Dopamine C. Norepinephrine D. Gamma-aminobutyric acid (GABA) E. Beta-endorphin
D. Gamma-aminobutyric acid (GABA)
Acetylcholine is the main neurotransmitter released by: A. preganglionic sympathetic neurons and cells of the adrenal medulla. B. cells of the adrenal medulla and postganglionic parasympathetic neurons. C. motor (somatic) neurons and postganglionic sympathetic neurons. D. preganglionic sympathetic neurons and motor (somatic) neurons. E. preganglionic sympathetic neurons and postganglionic sympathetic neurons.
D. preganglionic sympathetic neurons and motor (somatic) neurons.
Which of the following statements about norepinephrine is FALSE? A. Norepinephrine is a neurotransmitter. B. Norepinephrine binds to adrenergic receptors. C. Norepinephrine is a catecholamine. D. Dopamine is a precursor to norepinephrine. E. Epinephrine is in a different biosynthesis pathway than is norepinephrine.
E. Epinephrine is in a different biosynthesis pathway than is norepinephrine.
The central nervous system includes the: A. afferent nerves and spinal cord. B. efferent nerves and spinal cord. C. autonomic nervous system and the brain. D. brain stem and the autonomic nervous system. E. brain and spinal cord.
E. brain and spinal cord.
Immediately after an action potential, some of the voltage-gated _______ channels that repolarized the membrane are still _______.
K⁺; open
This occurs because the voltage-gated Na⁺ channels are either already open or have proceeded to the _______ state.
Na⁺; inactivated
What is the difference between temporal and spatial summation? Why can't spatial summation occur without also having temporal summation?
Panel 2. Temporal summation: inputs arrive from same presynaptic cell at slightly different times Panel 3. Spatial summation: inputs arrive from different synapses on the cell (must still be close enough in time to have effects sum) For inputs from two synapses to exhibit spatial summation, they still must occur close enough in time (temporal summation) to have their joints effects "sum" in time.
In the PNS, cells called _______ form individual myelin sheaths at regular intervals along the axons
Schwann cells
What are the four main functional zones of a neuron? For each zone, name specific structural feature (there are several possible) that contributes to the function of that zone, and briefly explain how it does.
Signal reception zone = dendrites and cell body; where synapses of other signaling neurons (incoming signals) are located Signal Integration zone (or trigger zone) = axon hillock (this is where cell first has voltage-gated Na+ and voltage-gated NK+ ion channels in the cell membrane; is where APs can first be generated, if enough local current reaches the axon hillock from the signal reception zone. Signal Conduction zone = axon; specialized for AP conduction (high number of V-gated ion channels) and often with insulated neuronal process (axon) due to myelin sheath which allow rapid conduction of APs to the axon terminal. Signal Transmission zone = axon terminals have Voltage-gated Ca2+ ion channels, and other features that lead to NT release into the synapse, to communicate ("transmit") the APs to the receiving cell (post-synaptic cell)
action potential
a brief all-or-none depolarization of the membrane, which reverses polarity in neurons; has a threshold and refractory period and is conducted without decrement
receptor potential
a graded potential produced at the peripheral endings of afferent neurons (or in separate receptor cells) in response to a stimulus
pacemaker potential
a spontaneously occurring graded potential change that occurs in specialized cells
Which is TRUE about the resting membrane potential? a) It is due mostly to ion permeability through leak channels. b) It has the same value in all cells. c) It is oriented so that the cell's interior is positive with respect to the extracellular fluid. d) Only nerve and muscle cells have a potential difference across the membrane at rest. e) It is measured during an action potential.
a) It is due mostly to ion permeability through leak channels.
Which statement concerning an AP in a single neuron is TRUE? a) speed of AP propagation down an axon is independent of stimulus strength b) a supramaximal stimulus can stimulate an AP during the absolute refractory period c) APs generally propagate from the axon terminal toward the initial segment of the axon d) the amplitude of an AP will be bigger with a stronger stimulus e) APs in the dendrites are smaller than APs at the trigger zone (initial segment) of an axon
a) speed of AP propagation down an axon is independent of stimulus strength
Which ion will cause the membrane potential at a section of the neuronal membrane to become relatively more negative, when that ion diffuses across the membrane through its ion channel? a. K+ b. Na+ c. K+ or Na+ d. need more information
a. K+
The functional region of a neuron containing the axon (but not the axon hillock) is termed the a. Signal conduction zone b. Signal internodal zone c. Signal reception zone d. Signal trigger zone e. Signal transmission zone
a. Signal conduction zone
Which of the following events occurs FIRST after an action potential arrives at an axon terminal? a. Voltage-gated calcium channels open. b. Calcium ions enter the axon terminal. c. Vesicles containing neurotransmitters move toward the axon terminal membrane. d. Exocytosis of neurotransmitter. e. Neurotransmitter binds to receptors on the postsynaptic cell
a. Voltage-gated calcium channels open.
At effectors, a post-ganglionic neuron of the parasympathetic division could release _______. a. only acetylcholine b. only norepinephrine c. both acetylcholine and norepinephrine d. either acetylcholine or norepinephrine (release only 1 but either is possible) e. glutamate
a. only acetylcholine
The first phase of the AP, called the depolarization phase in the axon, is produced through the: a. opening of voltage-gated sodium channels. b. opening of ligand-gated sodium channels. c. opening of voltage-gated potassium channels. d. closing of voltage-gated cation channels. e. inactivation of voltage-gated sodium channels
a. opening of voltage-gated sodium channels.
At the synaptic knob, voltage-gated __________ channels open, thereby stimulating the synaptic vesicles to release their neurotransmitters by exocytosis. a.) Ca2+ b.) Na+ c.) Cl- d.) K+
a.) Ca2+
Indicate the summative effect that brings the axon hillock (initial segment) closest to threshold. a.) Two EPSPs in proximity to each other b.) Two IPSPs located a large distance apart c.) Two EPSPs located a large distance apart d.) Two IPSPs in proximity to each other e.) One IPSP and one EPSP in proximity to each other
a.) Two EPSPs in proximity to each other
The relative refractory period of an axon coincides with the period of _______. a.) increased K+ permeability of the cell. b.) Increased Na+ flux through K+ channels. c.) activation and inactivation of voltage-dependent Na+ channels. d.) Na+ permeability that is greater than that during the depolarization phase. e.) increased K+ flux into the cell.
a.) increased K+ permeability of the cell.
Assume in a laboratory you were able to isolate a neuron and remove the acetylcholine receptors from the postsynaptic membrane. The substance __________ would no longer cause facilitation of this neuron. a.) nicotine b.) caffeine
a.) nicotine
Electrical signals in the dendrites and cell body of a neuron are called: a) Threshold potentials b) Graded potentials c) Neurotransmitters d) Action potentials e) Synapses
b) Graded potentials
Which describes the response of the voltage-gated ion channels when an axon is stimulated over the membrane's threshold potential? a) K + channels open and then Na+ channels open. b) Na+ channels are activated and then inactivated. c) K + channels and Na+ channels open at the same time. d) K + channels are opened when Na+ binds to the channel. e) K + influx causes the depolarization
b) Na+ channels are activated and then inactivated.
During the rising (depolarizing) phase of a neuronal action potential, a) PK+ is much greater than PNa+. b) PNa+ is much greater than PK+. c) PK+ is the same as PNa+. d) Mostly Na+ efflux out of the cell occurs. e) Mostly K + influx into the cell occurs
b) PNa+ is much greater than PK+.
Which best describes temporal summation? a) When the size of an EPSP depends on the size of the stimulus. b) When a 2nd stimulus occurs before effect of 1st stimulus at that synapse has ended. c) When the effects of several EPSPs are summed. d) When two synapses on different post-synaptic cells are stimulated at the same time. e) It always brings a postsynaptic cell to threshold.
b) When a 2nd stimulus occurs before effect of 1st stimulus at that synapse has ended.
In neurons, the strength of a stimulus is encoded... a) by the size of APs b) by the frequency of APs c) by the duration of APs d) by whether the AP peak is positive or negative e) by the endocytosis of synaptic vesicles
b) by the frequency of APs
The regions of uninsulated axon membrane between regions with myelin are the _______. a) ganglia b) nodes of Ranvier c) synaptic membranes d) glial cells e) pia mater
b) nodes of Ranvier
An inhibitory postsynaptic potential: a) is produced by simultaneous increases in permeability to both Na+ and K+ . b) occurs when a ligand-gated ion channel increases its permeability to K+ . c) is a small depolarization in a postsynaptic cell. d) can be summed with other IPSPs to lead to an AP in the postsynaptic cell. e) is produced by an increase in permeability to only Na+ .
b) occurs when a ligand-gated ion channel increases its permeability to K+ .
Cells forming the myelin sheath in the Peripherial Nervous System are a. Astrocytes b. Schwann cells c. Oligodendrocytes d. Microglial cell. e. Neurons
b. Schwann cells
The data on taxi drivers in London used MRI to estimate the size of the brain region involved in spatial memory. Which statement provides correct information and the strongest support for the hypothesis that experience influences the size of this brain region? a. This brain region was larger in older taxi drivers compared to newer trainees in London over a set multi-year period controlled for body size, socioeconomic status & education. b. This brain region was larger in successful trainees compared to those trainees when they first started taxi driver training. c. This brain region was larger in taxi drivers compared to non-taxi drivers in London, controlling for controlled for body size, socioeconomic status & education. d. None of these support the hypothesis that spatial experience in London matters.
b. This brain region was larger in successful trainees compared to those trainees when they first started taxi driver training.
An action potential results if: a. an action potential exceeds the threshold potential at the axon terminal. b. a graded potential exceeds the threshold potential at the axon hillock. c. a depolarization surpasses the refractory period. d. the threshold potential exceeds the depolarization of the nerve cell body. e. summation of graded potentials produces a hyperpolarization of the nerve cell membrane
b. a graded potential exceeds the threshold potential at the axon hillock.
Use of a territory requires good spatial memory. In territorial side-blotched lizards, the relative volume of this brain region involve in spatial memory a. is larger in nonterritorial males compared to territorial males. b. is smaller in nonterritorial males compared to territorial males. c. does not differ between nonterritorial & territorial males. d. of nonterritorial & territorial males differ when reared in the lab. e. of nonterritorial & territorial males only differ when reared in the lab.
b. is smaller in nonterritorial males compared to territorial males.
Which statements are CORRECT in helping to explain why the value of the RESTING MEMBRANE POTENTIAL in a motor neuron about -70 mV? a. the equilibrium potential of Na+ alone is about -90 mV b. the equilibrium potential of K+ alone is about -90 mV c. the equilibrium potential of Na+ alone is about +60 mV d. the equilibrium potential of K+ alone is about +60 mV e. the neuron has many more Na+ leak channels than K+ leak channels f. the neuron has many more K+ leak channels than Na+ leak channels g. the neuron has many more Na+ voltage-gated channels than K+ voltage-gated channels h. the neuron has many more K+ voltage-gated channels than Na+ voltage-gated channels i. the sodium/potassium ion pumps pf the cell balance the efflux/influx ("leak") rates for the Na+ and K+ ions.
b. the equilibrium potential of K+ alone is about -90 mV f. the neuron has many more K+ leak channels than Na+ leak channels i. the sodium/potassium ion pumps pf the cell balance the efflux/influx ("leak") rates for the Na+ and K+ ions.
How is the strength of a stimulus encoded by neurons? a.) By the duration of action potentials b.) By the frequency of action potentials c.) By the size of action potentials d.) By whether the action potential peak is positive or negative
b.) By the frequency of action potentials
Which is one of the major inhibitory neurotransmitters in the CNS? a.) Norepinephrine b.) Gamma-aminobutyric acid (GABA) c.) Beta-endorphin d.) Dopamine e.) Glutamate
b.) Gamma-aminobutyric acid (GABA)
Which is one of the most abundant excitatory neurotransmitters in the CNS? a.) Endorphin b.) Glutamate c.) Dopamine d.) Norepinephrine
b.) Glutamate
An inhibitory postsynaptic potential results from the opening of _______. a.) Cl- and/or Na+ channels. b.) K+ and/or Cl- channels. c.) Na+ and/or K+ channels.
b.) K+ and/or Cl- channels.
Normally, Na+ and K+ leakage channels differ because _______. a.) Na+ leakage channels are voltage-gated, while K+ leakage channels are ligand-gated. b.) Na+ ions diffuse through leakage channels into the cell, while K+ ions diffuse through leakage channels out of the cell. c.) Na+ leakage channels require ATP to transport ions, while K+ leakage channels do not. d.) Na+ leakage channels always remain open, while K+ leakage channels must be specifically activated to open.
b.) Na+ ions diffuse through leakage channels into the cell, while K+ ions diffuse through leakage channels out of the cell.
The fire alarm in your building is sounding off and you are hurriedly collecting your belongings before evacuating. Which portion of the nervous system is dominant? a.) Autonomic nervous system b.) Sympathetic nervous system c.) Afferent nervous system d.) Somatic motor nervous system e.) Parasympathetic nervous system
b.) Sympathetic nervous system
Indicate the summative effect that brings the axon hillock (initial segment) closest to threshold. a.) Two IPSPs in proximity to each other b.) Two EPSPs in proximity to each other c.) Two EPSPs located a large distance apart d.) Two IPSPs located a large distance apart
b.) Two EPSPs in proximity to each other
Substances that cause facilitation of a neuron __________. a.) alter the resting membrane potential of a presynaptic neuron by making it hyperpolarized b.) cause the neuron to fire that may not under the same circumstances in the absence of the facilitator c.) disable the trigger zone of the axon hillock, thereby preventing it from reaching threshold d.) continually create additional ligand-gated ion channels at the receptor region
b.) cause the neuron to fire that may not under the same circumstances in the absence of the facilitator
Graded potentials result from the opening of _______. a.) Na+/K+ ATPase pumps. b.) ligand-gated channels. c.) leakage channels. d.) voltage-gated channels.
b.) ligand-gated channels.
During an action potential _______. a.) negative charges inside the cell move away from the region that is depolarizing. b.) positive charges inside the cell move away from the region that is depolarizing. c.) negative charges outside the cell move toward the region that is depolarizing. d.) positive charges outside the cell move away from the region that is depolarizing.
b.) positive charges inside the cell move away from the region that is depolarizing.
The following information best describes the __________ phase of an action potential. • A membrane potential reading of +10 mV • Inactivated voltage-gated sodium channels • Open voltage-gated potassium channels a.) depolarization b.) repolarization c.) hyperpolarization d.) resting
b.) repolarization
The central nervous system (CNS) is composed of the _______ in the skull and the _______ in the vertebral column.
brain; spinal cord
Which is TRUE about typical, resting neurons? a) The plasma membrane is most permeable to sodium ions. b) The concentration of sodium ion is greater inside the cell than outside. c) The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions. d) The plasma membrane is completely impermeable to sodium ions. e) The plasma membrane is completely impermeable to potassium ions.
c) The permeability of the plasma membrane to potassium ions is much greater than its permeability to sodium ions.
The main role of calcium ions at chemical synapses is to a) depolarize the axon terminal of the presynaptic cell. b) bind to neurotransmitter receptors on the postsynaptic cell. c) cause fusion of synaptic vesicles with the plasma membrane of the axon terminal. d) interfere with IPSPs in the postsynaptic cell. e) diffuse across the synaptic space and enter the postsynaptic cell.
c) cause fusion of synaptic vesicles with the plasma membrane of the axon terminal.
According to the equation expressed as Ohm's law, which of these would cause the greatest increase in current? a) doubling both voltage and resistance b) reducing both voltage and resistance by half c) doubling voltage and reducing resistance by half d) reducing voltage by half and doubling resistance e) quadrupling both voltage and resistance
c) doubling voltage and reducing resistance by half
An action potential does not re-stimulate the adjacent membrane that was previously depolarized and experienced an AP because a) stimulation is inhibited by the myelin sheath. b) it is impossible for an AP to be propagated along an axon toward the nerve cell body. c) that area of the membrane is in the absolutely refractory period. d) the resting membrane potential of the axon is too positive. e) the resting membrane potential of the axon is too negative.
c) that area of the membrane is in the absolutely refractory period.
Which of the following is CORRECT about the glutamate neurotransmitter receptors involved in Long Term Potentiation (LTP) in mammals (diagram below depicts events illustrating LTP)? a. Glutamate receptors are all Na+ ion channels. b. Glutamate receptors can be either Na+ or Mg2+ ion channels c. Glutamate receptors can be either Na+ or Ca2+ ion channels d. Glutamate receptors can always open under low frequency of APs in presynaptic cell. e. Glutamate receptors can never open under low frequency of APs in presynaptic cell.
c. Glutamate receptors can be either Na+ or Ca2+ ion channels
Which of the following is incorrect about memory and learning in mammals? a. The hippocampus is involved in long-term memory, and memories are "stored" in cerebrum. b. Long term potentiation is a major mechanism for increasing efficiency of the synapse. c. Long term potentiation is a major mechanism for causing greater habituation. d. Memories are "stored" by increasing the efficiency of the synapse between two neurons. e. Long-term potentiation occurs when repetitive stimulation of hippocampal tissue leads to an increase in the response of the postsynaptic neuron.
c. Long term potentiation is a major mechanism for causing greater habituation.
Glial cells are a. only within the CNS (central nervous system) b. only within the PNS (peripheral nervous system) c. a very common type of cell in the nervous system d. the most common type of neuron e. a type of interneuron
c. a very common type of cell in the nervous system
In a "resting-and-digesting" (couch-potato) situation _______. a. sympathetic pathways would transmit outputs and parasympathetic would not b. parasympathetic pathways would transmit output and sympathetic paths would not c. both sympathetic and parasympathetic pathways would transmit outputs d. only parasympathetic pathways would transmit outputs e. only sympathetic pathways would transmit outputs
c. both sympathetic and parasympathetic pathways would transmit outputs
Which of the following correctly and most completely describes what would occur with decreased overall sympathetic nervous stimulation in the body? a. decreased gastrointestinal (GI) secretion, GI motility, GI muscle tone b. decreased heart rate, respiration rate, GI secretion, GI motility, GI tone c. increased GI secretion, GI motility, GI muscle tone, decreased heart rate d. increased respiration rate, heart rate, decreased GI secretion, GI motility, GI muscle tone e. increased heart rate, respiration rate, GI secretion, GI motility, GI tone
c. increased GI secretion, GI motility, GI muscle tone, decreased heart rate
Which of the following statements about norepinephrine is FALSE? a.) Norepinephrine is a neurotransmitter. b.) Norepinephrine is a catecholamine. c.) Epinephrine is a precursor to norepinephrine. d.) Norepinephrine binds to adrenergic receptors. e.) Dopamine is a precursor to norepinephrine.
c.) Epinephrine is a precursor to norepinephrine.
Postganglionic neuron cell bodies of the autonomic nervous system have which category of neurotransmitter receptor? a.) Serotonin receptors b.) Adrenergic receptors c.) Nicotinic acetylcholine receptors d.) Muscarinic acetylcholine receptors e.) Dopamine receptors
c.) Nicotinic acetylcholine receptors
As an action potential propagates along a membrane, it continues to travel only forward from the actively depolarizing region because _______. a.) all of the potassium channels in the region behind the actively depolarizing region remain inactivated for several seconds. b.) the actively depolarizing region sends positive local current in the forward direction, but it sends negative local current backward. c.) the membrane area behind the actively depolarizing region is in the absolute refractory period. d.) local positive ionic current is only able to flow forward from the actively depolarizing region. e.) the inside of the membrane in the region behind the actively depolarizing region repels positive ionic charges.
c.) the membrane area behind the actively depolarizing region is in the absolute refractory period.
During this time, some of the voltage-gated Na⁺ channels have returned to their _______ state, and could therefore open again.
closed
The movement of electrical charge is called _______ and the charge carriers in biological systems is/are _______.
current; ions
Exocytosis of neurotransmitter into the synaptic cleft is triggered by an intracellular messenger, that diffuses into the cell response to the AP that occurs in the axon terminal's membrane. This diffusing ion is _______. a) K + ions b) Na+ ions c) Mg+ions d) Ca2+ ions e) Clions
d) Ca2+ ions
Which is most directly responsible for the repolarizing phase of an action potential? a) Voltage-gated Na+ channels are opened. b) Na+ /K+ ATPase pump restores ions to their original locations inside & outside of the cell. c) The permeability to Na+ increases greatly. d) Na+ permeability decreases while K+ permeability increases e) ATPase destroys the energy supply that was maintaining the action potential at its peak.
d) Na+ permeability decreases while K+ permeability increases
Which is FALSE about interneurons? a) They receive synaptic input from other neurons in the CNS. b) They sum excitatory and inhibitory synaptic inputs. c) They deliver synaptic input on other neurons. d) They synapse with effector organs in the PNS. e) They can transmit information between afferent neurons and efferent neurons
d) They synapse with effector organs in the PNS.
______________ detect environmental signals and convey this information to the central nervous system. _____________ convey signals from one neuron to another and ___________ convey signals from the central nervous system to effector organs. a. Sensory neurons; Efferent neurons; interneurons b. Efferent neurons; Interneurons; sensory neurons c. Interneurons; Sensory neurons; efferent neurons d. Sensory neurons; Interneurons; efferent neurons e. Efferent neurons; Afferent neurons; interneurons
d. Sensory neurons; Interneurons; efferent neurons
Which of the following would cause more neurotransmitter to be released by the presynaptic cell into the synaptic cleft? a. more acetylchoinesterase in the synaptic cleft b. bigger (mV) APs in presynaptic cell c. bigger (mV) APs in postsynaptic cell d. higher rate of APs in presynaptic cell e. higher rate of APs in postsynaptic cell
d. higher rate of APs in presynaptic cell
Compared to transmission across chemical synapses, transmission across an electrical synapse is: a. slower b. more diverse. c. restricted to going in one direction. d. mediated by gap junctions. e. more common in vertebrates than in invertebrates.
d. mediated by gap junctions.
High-frequency stimulation leading to synaptic strengthening is an example of: a. fast axonal transport. b. ionotropic modulation. c. cable properties. d. synaptic plasticity. e. signal transduction pathways.
d. synaptic plasticity.
If acetylcholinesterase became mutated and nonfunctional, what would be the immediate result? a.) Neurotransmitter-filled synaptic vesicles would be unable to fuse and release their products into the synaptic cleft. b.) Acetylcholine synthesis would immediately cease. c.) Acetylcholine present in the synaptic cleft would no longer depolarize the postsynaptic membrane. d.) Acetylcholine would build up in the synaptic cleft.
d.) Acetylcholine would build up in the synaptic cleft.
__________ the time between signals sent from the same presynaptic terminal increases the strength of the graded potential. This is an example of __________ summation. a.) Reducing; spatial b.) Increasing; temporal c.) Increasing; spatial d.) Reducing; temporal
d.) Reducing; temporal
The portion of the peripheral nervous system that is composed of nerve fibers that innervate skeletal muscle is called the _______. a.) sympathetic nervous system. b.) afferent nervous system. c.) parasympathetic nervous system. d.) somatic motor nervous system. e.) autonomic nervous system.
d.) somatic motor nervous system.
Which statement about graded membrane potentials is FALSE a) Graded potentials can be produced on the post-synaptic membrane at a synapse. b) Graded potentials diminish in strength over distance. c) Graded potentials that add up (sum) will produce a change in the membrane potential. d) Graded potentials can vary in strength and can even hyperpolarize a membrane. e) Graded potentials are mainly produced by voltage-gated sodium and potassium channels.
e) Graded potentials are mainly produced by voltage-gated sodium and potassium channels.
Which of the following statements about EPSPs is FALSE? a) They are produced by the opening of ligand-gated sodium channels. b) They transmit signals over relatively short distances. c) They depolarize postsynaptic cell membranes. d) They are able to sum together. e) They are always the same amplitude.
e) They are always the same amplitude.
In the refractory period of a neuronal membrane ... a) the absolute refractory period is when another AP cannot be initiated at the membrane undergoing an ap potential, no matter how strong the stimulus. b) the relative refractory period is when another AP can be initiated at the membrane that has just undergone an AP if a stronger than normal stimulus is applied. c) the refractory period prevents the AP from spreading back over the part of the membrane that just underwent an AP. d) the refractory period places an upper limit on the frequency of AP s in a neuron's axon. e) all of the above choices are correct.
e) all of the above choices are correct.
Which is NOT an example of a graded potential? a) a receptor potential in a sensory receptor cell b) a depolarizing excitatory postsynaptic potential (EPSP) c) a hyperpolarizing inhibitory postsynaptic potential (IPSP) d) an inhibitory post synaptic potential e) an action potential
e) an action potential
Which of the following statements is FALSE? a. Graded potentials vary in magnitude, whereas action potentials are always the same magnitude (in a given cell type). b. Graded potentials vary in duration, whereas action potentials are always the same duration (in a given cell type). c. Graded potentials occur in dendrites and the cell body, whereas action potentials occur in the axons. d. Graded potentials are caused by the opening and closing of many kinds of channels, whereas action potentials are caused by the opening and closing of voltage-gated ion channels. e. Graded potentials are suitable as long-distance signals, whereas action potentials decay quickly.
e. Graded potentials are suitable as long-distance signals, whereas action potentials decay quickly.
Which of the following statements is TRUE about nervous system structures? a. Neurons are composed of groups of nerves. b. Nerves act as pipes in the body, transporting fluid. c. Neurotransmitter is released at the axon terminal via endocytosis d. Synaptic transmissions is affected by the rate that synaptic vesicles diffuse down the axon. e. None of the above are true
e. None of the above are true
The Vole species with pair-bonding and male parental care is monogamous. Another vole species is polygynous, does not form pair bonds, and males commit infanticide. What is a FALSE statement? a. The gene for the vasopressin-1A receptor also controls where it is expressed in the brain. b. Monogamous and polygamous vole species differ in brain distribution of vasopressin-1A receptors. c. Polygamous males transgenic for the monogamous species' vasopressin-1A receptor gene show pup care and pair bonding. d. Polygamous males transgenic for the monogamous species' vasopressin-1A receptor gene show a similar pattern of receptor expression in key brain areas. e. Polygamous males transgenic for the monogamous species' vasopressin-1A receptor gene do not show pup care or pair bonding.
e. Polygamous males transgenic for the monogamous species' vasopressin-1A receptor gene do not show pup care or pair bonding.
Which of the following kinds of neurons are NOT generally cholinergic? a.) Preganglionic sympathetic neurons b.) Postganglionic parasympathetic neurons c.) Preganglionic parasympathetic neurons d.) Somatic motor neurons e.) Postganglionic sympathetic neurons
e.) Postganglionic sympathetic neurons
An action potential generates local currents that tend to __________ membrane regions immediately adjacent to the site where the action potential is occurring. a.) stabilize b.) neutralize c.) hyperpolarize d.) repolarize e.) depolarize
e.) depolarize
Acetylcholine is the main neurotransmitter released by _______. a.) preganglionic sympathetic neurons and postganglionic sympathetic neurons. b.) cells of the adrenal medulla and postganglionic parasympathetic neurons. c.) preganglionic sympathetic neurons and cells of the adrenal medulla. d.) motor neurons and postganglionic sympathetic neurons. e.) preganglionic sympathetic neurons and motor neurons.
e.) preganglionic sympathetic neurons and motor neurons.
In most neurons, generation of a/an _______ causes the release of _______ which communicate with other cells.
electrical signal; neurotransmitters
synaptic potential
graded potential produced in the post-synaptic neuron in response to the release of a neurotransmitter by a presynaptic terminal; may be depolarizing (an excitatory postsynaptic potential or EPSP) or hyperpolarizing (an inhibitory postsynaptic potential or IPSP)
The magnitude of the resting membrane potential depends on two factors: differences in specific _______ in the intracellular and extracellular fluids and the membrane _______ to those ions.
ion concentrations; permeabilities
During this time, a second action potential can be produced, but only if the stimulus strength is _______ than usual.
larger
Graded potentials result from the opening of _______.
ligand-gated channels
In biological systems, membrane potential is measured in the units, _______.
millivolts
Action potential propagation occurs rapidly in the axons of neurons covered by _______.
myelin
The resting membrane potential exists because of a tiny excess of _______ ions inside the cell and an excess of _______ ions outside that are electrically attracted to each other across the _______ of the cell.
negative; positive; plasma membrane
The basic unit of the nervous system is the individual nerve cell, or _______.
neuron
The bulk of the intracellular and extracellular fluids remain _______.
neutral
The spaces between adjacent sections of myelin where the axon's plasma membrane is exposed to the extracellular fluid are the _______.
nodes of Ranvier
The _______ consists of the nerves that connect the CNS with the body's _______, glands, and sense organs.
peripheral nervous system (PNS); muscles
The difference in the amount of charge between two locations is called a/an _______.
potential
This is the _______ period, which coincides roughly with the period of hyperpolarization.
relative refractory; hyperpolarization
All cells under resting conditions have a potential difference across their plasma membranes called the _______, with the inside of the cell _______ charged with respect to the outside.
resting membrane potential; negatively
An experimentor uses an electrical stimulator to inject a resting neuron with 3 different currents: 5, 10, and 25 microamps. No action potential occurs at 5 and 10 microamps, so those are called _______.
subthreshold stimuli
threshold potential
the membrane potential at which an action potential is initiated
resting membrane potential or resting potential
the steady potential of an unstimulated cell
equilibrium potential
the voltage difference across a membrane that produces a flux of a given ion species that is equal but opposite to the flux due to the concentration gradient of that same ion species that is equal but opposite to the flux due to the concentration gradient of that same ion
potential or potential difference
the voltage difference between two points due to separated electrical charges of opposite sign
membrane potential or transmembrane potential
the voltage difference bewteen the inside and outside of a cell
An action potential does occur at 25 microamps, so it is called a/an _______.
threshold stimulus
If the neuron was stimulated with a 50 microamp current, an action potential _______ occur, and it would be _______ in size to the 25 microamp-induced action potential.
would; similar