Biology: The Dynamic Science (MindTap Course List)
4th Edition
ISBN: 9781305389892
Author: Peter J. Russell, Paul E. Hertz, Beverly McMillan
Publisher: Cengage Learning
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Textbook Question
Chapter 39, Problem 6TYK
In the propagation of a nerve impulse:
a. the refractory period begins as the K+ channel opens, allowing K+ ions to flow outward along their concentrationgradient.
b. Na+ ions flow out of the axon with their concentration gradient.
c. positive charges lower the membrane potential to its lowestaction potential.
d. gated K+ channels open at the same time as the activationgate of Na+ channels closes.
e. the depolarizing stimulus lowers the membrane potential toopen the Na+ gates.
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During a relative refractory period of an action potential
A.
Another action potential can be fired, it just takes a greater stimulus for the membrane potential to reach threshold
B.
Na+ channels are either already open or are inactivated therefore the membrane absolutely can not produce another action potential, no matter how intense the stimulus
C.
Ca++ flows out of the cell, causing hyperpolarization and a need for a greater stimulus to generate the action potential
D.
The presynaptic neuron "tells" the postsynaptic neuron about the "relative" strength of signal
E.
None of the above are correct
Which of the following is TRUE regarding the absolute and relative refractory periods of the action potential (AP)?
A. The absolute refractory period may be overcome if enough excitatory stimulation is applied to the neuronal membrane.
B. The absolute refractory period is due the closing of the activation gate of voltage gated sodium channels at the peak of the AP.
C. The relative refractory period is due to the closing of the activation gate of voltage gated potassium channels during the overshoot phase of the AP.
D. The relative refractory period is due the closing of the inactivation gate of voltage gated sodium channels .
E. All of the above statements are FALSE.
Choose the correct sequence of events along an axon: a. Resting potentials are propagated along a stimulated axon, causing a very small action potential. b. A threshold stimulus opens K+ channels and the ions diffuse in, depolarizing the cell membrane. Then Na+ channels open, Na+ exits, and the cell membrane repolarizes, generating an action potential that stimulates adjacent cell membrane, forming the impulse. c. A threshold stimulus opens Na+ channels and the ions diffuse in, depolarizing the cell membrane. Then K+ channels open, K+ exits, and the cell membrane repolarizes, generating an action potential that stimulates adjacent cell membrane, forming the impulse. d. A threshold stimulus opens Na+ channels and the ions diffuse in, depolarizing the cell membrane. Then K+ channels open, K+ exits, and the cell membrane repolarizes, generating an action potential that inhibits adjacent cell membrane, forming the impulse
Chapter 39 Solutions
Biology: The Dynamic Science (MindTap Course List)
Ch. 39.1 - Prob. 1SBCh. 39.1 - Prob. 2SBCh. 39.1 - Prob. 3SBCh. 39.2 - Prob. 1SBCh. 39.2 - Prob. 2SBCh. 39.3 - Prob. 1SBCh. 39.3 - Prob. 2SBCh. 39.4 - Prob. 1SBCh. 39 - Prob. 1TYKCh. 39 - Prob. 2TYK
Ch. 39 - An example of a synapse could be the site where:...Ch. 39 - Prob. 4TYKCh. 39 - The major role of the Na+/K+ pump is to: a. cause...Ch. 39 - In the propagation of a nerve impulse: a. the...Ch. 39 - Which of the following does not contribute to...Ch. 39 - Which of the following statements best describes...Ch. 39 - Prob. 9TYKCh. 39 - Prob. 10TYKCh. 39 - Prob. 11TYKCh. 39 - Prob. 12TYKCh. 39 - Prob. 13TYKCh. 39 - Prob. 14TYKCh. 39 - Prob. 15TYKCh. 39 - Prob. 16TYKCh. 39 - You learned in this chapter that Na+/K+ active...Ch. 39 - Prob. 2ITDCh. 39 - Prob. 3ITD
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- Assume presynaptic excitatory neuron A terminates on a postsynaptic cell near the axon hillock and presynaptic excitatory neuron B terminates on the same postsynaptic cell on a dendrite located on the side of the cell body opposite the axon hillock. Explain why rapid firing of presynaptic neuron A could bring the postsynaptic neuron to threshold through temporal summation, thus initiating an action potential, whereas firing of presynaptic neuron B at the same frequency and the same magnitude of EPSPs may not bring the postsynaptic neuron to threshold.arrow_forwardWhat membrane protein of the neuron is responsible for briefly increasing the Na+ permeability of the membrane during the rising phase of the nerve impulse? a. the sodium-potassium pump b. the voltage gated potassium channel c. the voltage gated sodium channel d. the stimulus gated sodium channel e. the ligand gated ion channelarrow_forwardDetermine whether each statement is true or false. If a statement is false, explain why. A. Voltage gated sodium channels are quick to open and slow to close, while voltage gated potassium channels are quick to open and slow to close. 6. Before a second action potential can be generated, the concentration of sodium and potassium on either side of the cell membrane must be fully restored. C. The strength of an action potential is represented by the amplitude of the wave. A stronger stimulus will generate an action potential with a higher peak than a weaker stimulus. D.. Action potentials travel in a non-decremental manner down the axon, with the voltage constantly being regenerated along the way, unlike graded potentials which quickly diminish over short distances. E. Contiguous conduction is faster than saltatory conduction. F. Action potentials originate in the axon hillock and travel down the axon to the terminal boutons (pre-synaptic axon terminals).arrow_forward
- In signal transduction in the dark, the cGMP plays what role? a. It promotes an action potential in the bipolar cell b.It promotes a more hyperpolarized resting potential c. It activates transducin d. It opens non-selective cation channels e. It deactivates cGMP phosphodiesterasearrow_forwardDuring the action potential, which of the following activity is LIKELY to occur? Select one: a. Na+ channels open at the beginning of the action potential, and Na+ moves into the axon b. Na+ channel passages become smaller and get retracted at the beginning of the action potential c. Na+ channels are less active and static throughout the action potential process d. less Na+ is pumped to the axon when the action potential is triggeredarrow_forwardUsing cable theory to describe axon conduction would tell us a. the larger the diameter of the axon the faster the propagation of the action potential b. the larger the diameter of the axon the slower the propagation of the action potential c. the smaller the diameter of the axon the faster the propagation of the action potential d. that having big axons is of no benefit and only takes up a lot of space e. the nervous system mainly has small axons because they are much faster than large onesarrow_forward
- Local anesthetics "block" the action potential and therefore do not allow "pain" information to proceed to the brain and spinal cord. In the presence of these molecules (local anesthetics) 'threshold' is essentially "ignored". The molecules most logically work by: 23. a. Decreasing the intracellular [potassium] b. Blocking the opening of the voltage-gated potassium channels c. Decreasing the extracellular [sodium] d. Blocking the opening of the voltage-gated sodium channelsarrow_forwardAction potential conduction velocity is more rapid in a myelinated axon than an unmyelinated one because in a myelinated axon: a. the action potential travels as a continuous wave. b. there is a decrease in membrane resistance. c. the action potential jumps along the axon. d. there is an increase in membrane capacitance. e. there is an increase in the ion gradients.arrow_forwardThere is a type of toxin found in the liver of the puffer fish that prevents the opening of voltage-gated Na+ channels in neurons. The effect of this toxin is to: Group of answer choices A. prevents the initiation of the action potential B. depolarizes the membrane potential and maintains it depolarized C. prolongs the return of the membrane potential to the resting level D. increases the duration of the action potentialarrow_forward
- Which of the following statements is TRUE of the action potential? A. At the peak of the action potential there are approximately an equal amount of open voltage gated sodium and potassium channels B. To reach threshold the action potential requires the activity of sodium potassium pump C. During the rising phase (prior to the peak) of the action potential more voltage gated sodium channels are open than voltage gated potassium channels D. None of the choice options are TRUE of the action potential E. The overshoot phase (below resting membrane potential) is a result of voltage gated sodium channels taking a long time to close.arrow_forwardPost synaptic neurons membrane potentials are less negative than resting membrane potentials when this occur A. Creates a new set point for the resting membrane potential B. Has a lower propensity to produce an action potential C. Reacts by generating action potential D. Higher chance of reaching the potential thresholdarrow_forwardWhich of the following situations correctly illustrates the all-or-none principle? Select one: o a. A smaller voltage change will result in a smaller nerve impulse. o b. A stronger impulse can be generated by increasing the number of open voltage-gated sodium channels during depolarization. O C. A greater voltage change and a smaller voltage change will result in the same action potential as long as the threshold potential has been reached. o d. A faster impulse can be generated with a voltage change that is greater than the threshold potential.arrow_forward
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