Which of the following statements regarding a neuronal action potential is FALSE? O The rising phase of a neuronal action potential is caused by Na+ influx. O The falling phase of a neuronal action potential is caused by K+ efflux. O The infux of Ca2+ into synaptic knobs (terminals) induces exocytosis of neurotransmitters. O The opening of Cl- channels on a neuron will depolorize the cell.

Which of the following statements regarding a neuronal action potential is FALSE? O The rising phase of a neuronal action potential is caused by Na+ influx. O The falling phase of a neuronal action potential is caused by K+ efflux. O The infux of Ca2+ into synaptic knobs (terminals) induces exocytosis of neurotransmitters. O The opening of Cl- channels on a neuron will depolorize the cell.

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter4: Principles Of Neural And Hormonal Communication

Section: Chapter Questions

Problem 3TAHL

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If action potential propagation from one neuron to another neuron requires ACh release, what event at the synaptic cleft explains the need for action potentials to arrive at a high rate before the post-synaptic membrane achieves threshold? the lack of sodium voltage gated channels on the post-synaptic membrane O the rapid breakdown of ACh by ACHE at the synaptic cleft the slow release of ACh by the synaptic vessicles the slow movement of sodium through chemical gates Previous Next MacBook Air
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 in a direction that would tend to move it into the cell. O 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. O The electrical gradient for Na+ is in a direction that would tend to move it into the cell.
Which of the following is true of ACh (acetylcholine)? O It cannot be degraded within the synaptic cleft to which it was released; it must be internalized and degraded by the cell that receives it O It is always excitatory because it causes the entrance of Na+ into a cell which leads to an increase in intracellular mV O It is released via exocytosis from the axon terminal of a somatic motor neuron O It is released via exocytosis from all pre-ganglionic motor neurons of the ANS
This patient's hypokalemia was due to his profuse sweating the previous day and the subsequent loss of potassium ions at the kidneys. How would his hypokalemia affect action potential generation? O the cell membrane potential will become more positive and facilitate action potential generation O the cell membrane potential will become more negative and it will be more difficult to generate an action potential action potentials will be generated at a higher frequency O a and c
Once an action potential reaches a neurotransmitter release site, the release of the neurotransmitter is triggered by: The influx of Na* through voltage-gated channels. O The efflux of Na* through voltage-gated channels. The influx of K* through voltage-gated channels. The efflux of K+ through voltage-gated channels. The influx of Ca²+ through voltage-gated channels. O The efflux of Ca2+ through voltage-gated channels.
Excitatory neurons A and B both synapse with neuron C. Neuron A releasesa neurotransmitter, and neuron B releases the same type and amount ofneurotransmitter plus a neuromodulator that produces EPSPs in neuron C.Action potentials produced in neuron A alone can result in action potentialproduction in neuron C. Action potentials produced in neuron B alone alsocan cause action potential production in neuron C. Which results in moreaction potentials in neuron C, stimulation by only neuron A or stimulationby only neuron B? Explain.
Many neurotransmitters trigger depolarisation by binding their receptors and gating an ion channel that allows Nat influx. What happens if a neurotransmitter such as GABA, binds its receptor, gating a chloride channel (CI)? Select the (one) CORRECT answer. O a. The neuron becomes depolarised. Ob. The membrane potential does not change O c. The neuron becomes hyperpolarised O d. The neuron fires an action potential
"The local anesthetic, novacaine, used by most dentists blocks voltage-gated Na+ channels. Why would it result in numbness (loss of feeling)?" It prevents action potentials from occurring It prevents local potentials from occurring It prevents the membrane potential from returning to normal It prevents exocytosis of neurotransmitter O O
Predatory cone snails are beautiful (picture below), but deadly - they release a cocktail of toxins that affect multiple aspects of neuronal function. One of these toxins is called omega-conotoxin, and it blocks (inhibits) voltage-gated calcium channels. What impact would this have on chemical synaptic transmission? Action potentials cannot be initiated O b. Action potentials can be initiated, but cannot propagate down axons and thus cannot reach terminals O c. Action potentials can propagate and reach terminals, but neurotransmitter release is not possible o d. Neurotransmitters can be released from terminals, but they cannot bind to receptors O . Neurotransmitters can be released and can bind to receptors, but PSPS will not occur
A post-synaptic cell receives a signal that causes it to hyperpolarize. Which statement is NOT true about this dynamic? O The cell is now more negative than it was before. This describes an EPSP It will be harder for the cell to reach threshold and generate a new action potential. O This could have been achieved through either spatial or temporal summation.
The falling phase of the action potential is due to: Na+ influx through voltage-gated Na+ channels. O Na* efflux through voltage-gated Na* channels. OK* influx through voltage-gated K+ channels. O K+ efflux through voltage-gated K channels. O Nat influx through Na* leak channels. Na efflux through Na+ leak channels. O K+ influx through K+ leak channels. O K+ efflux through K+ leak channels.
The trigger for an action potential is: Osodium Opotassium O sodium and potassium O the voltage-gated sodium channels are closed O the threshold potential