Cardiopulmonary Anatomy & Physiology
7th Edition
ISBN: 9781337794909
Author: Des Jardins, Terry.
Publisher: Cengage Learning,
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Textbook Question
Chapter 12, Problem 1RQ
Which of the following is the rapid upstroke in the action potential?
A. Phase 0
B. Phase 1
C. Phase 2
D. Phase 3
Expert Solution & Answer
Summary Introduction
Introduction:
An action potential is generated and propagated by the heart for its contraction. Action potentials are the electrical currents that move across the membrane of the cardiac cells. These are identical to the action potential of neurons, cardiac muscles, and skeletal muscles. The primary ions responsible for the electrical differences are potassium, calcium, and sodium.
Answer to Problem 1RQ
Correct answer:
Phase 0.
Explanation of Solution
Justification for the correct answer:
Option (a) is, ‘Phase 0.’ It is the phase of rapid depolarization. The ventricular muscle fibers are activated by the electrical impulses initiated by the sinoatrial node. A change in the resting membrane is brought about by this. It allows the inward flow of sodium ions inside the cells. At the end of depolarization, the voltage is +30 mV (millivolts). This leads to a production of rapid upstroke in the action potential. Hence, option (a) is correct.
Justification for the incorrect answers:
Option (b) is, ‘Phase 1.’ Phase 1 stage is associated with the repolarization of the membrane. The potassium ion channels get opened just after phase 0, which allows the inflow of potassium ions. So, it is an incorrect option.
Option (c) is, ‘Phase 2.’ Phase 2 stage is the plateau stage. This stage is marked by the inflow of calcium ions, which slows the outward flow of potassium ions. So, it is an incorrect option.
Option (d) is, ‘Phase 3.’ Phase 3 stage is the final rapid polarization. The inward flow of the calcium ions stops. The rate of repolarization increases as the outward flow of potassium ions accelerates. So, it is an incorrect option.
Hence, options (b), (c), and (d) are incorrect.
Conclusion
Thus, it can be concluded that the rapid upstroke in the action potential takes place in phase 0 of the action potential. The sinoatrial node initiates the electrical impulse which activates the ventricular muscle fibers.
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Students have asked these similar questions
Which of the following is the plateau stage of the action potential? A. Phase 0 B. Phase 1 C. Phase 2 D. Phase 3
Which of the following is the rapid upstroke in the action potential?A. Phase 0B. Phase 1C. Phase 2D. Phase 3
The made-up drug leakyhose degrades myelin resulting in myelin becoming more porous and therefore a poor insulator.
2.) Which of the following would NOT be an effect of leakyhose?
A. Propagation of the action potential would likely slow
B. The action potential may degrade because it can’t properly be regenerated
C. The action potential would not propagate but would rather reverse directions
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Chapter 12 Solutions
Cardiopulmonary Anatomy & Physiology
Ch. 12 - 1. Which of the following is the rapid upstroke in...Ch. 12 - Prob. 2RQCh. 12 - Prob. 3RQCh. 12 - Prob. 4RQCh. 12 - Which of the following slows the heart rate and AV...Ch. 12 - Prob. 6RQCh. 12 - Prob. 7RQCh. 12 - Which of the following means the ability to...Ch. 12 - An electrical difference across the fibers of the...Ch. 12 - Prob. 10RQ
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- In an experiment you place a neuron and its synaptic contacts into a medium containing no calcium ions. You stimulate the neuron causing an action potential to propagate down the axon into the axon terminal of the neuron. 3.) What is the most likely result of this experimental manipulation? A. Prolong the refractory period of the action potential B. Decrease the time required to move sodium ions out of the axon terminal C. Prevent neurotransmitter from binding to receptors on postsynaptic cells D. Enhance the voltage changes associated with the action potential E. Prevent release of neurotransmitter into the synapsearrow_forwardWhich 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_forwardWhich of the following voltages would most likely be measured during the relative refractory period? Choose one answer. a. +30 mV b. 0 mV c. -45 mV d. -80 mvarrow_forward
- The _________________ of action potentials states that once an action potential begins, it will travel all the way down the axon without losing any strength. Select one: a. 1st law b. 2nd law c. None of these. d. order of recruitment law e. all-or-none lawarrow_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_forwardAssume a neuron's membrane potential is -60 mV, what's the net consequence on the membrane potential of a 5 picoamp (pA) sodium current that occurs simultaneously with a 5 pA chloride current? a. There's a 5 pA hyperpolarizing current b. There's a 10 pA depolarizing current c. There's a 10 pA hyperpolarizing current d. There's a 5 pA depolarizing current e. There's no change in the membrane potentialarrow_forward
- Any change in a neuron's membrane potential that moves the membrane potential to a value more negative than the resting potential (e.g. -120mv) is: a. Hypopolarization b. Depolarization c. An action potential d. HyperpolarizationNOTE: A IS INCORRECTarrow_forwardDuring an action potential, the inside of the cell membrane becomes more positive than the outside. Why does this happen? a. During depolarization, the sodium ions rush in and the potassium ions have not begun rushing out, making the inside more positive. b. During depolarization, the sodium ions rush in and the potassium ions have not begun rushing out, making the outside more positive. c. During depolarization, the potassium ions rush in and the sodium ions have begun rushing out, making the inside more positive. d. During depolarization, the sodium ions rush in and the potassium ions have begun rushing out, making the outside more positive.arrow_forwardWhich of the following primarily reflects the opening of voltage-gated Na+ channels? A. The resting membrane potential B. The depolarization phase of the action potential C. The threshold potential D. The repolarization phase of the action potential E. All of the abovearrow_forward
- Can you explain to me why choice E is the correct answer and break down why the other options are false?Select the choice option that is TRUE regarding the absolute and relative refractory periods of the action potential (AP). A. The absolute refractory period occurs when the activation gate of voltage gated sodium channel closes at the peak of the AP B. The relative refractory period occurs when the inactivation gate of voltage gated sodium channels closes at the peak of the AP C. The relative refractory period occurs when the activation gate of voltage gated potassium channels opens at the peak of the AP D. The absolute refractory period may be overcome if enough excitatory stimulation is applied to the neuronal membrane E. All of the choice options are FALSE regarding the absolute and relative refractory periods of the AParrow_forwardWhich of the following allows the cell to recover from hyperpolarization during an action potential? A. Stimulus gated sodium channels B. voltage gated sodium channels C. voltage gated potassium channels D. sodium/potassium pumparrow_forwardWhich 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.arrow_forward
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