7. Which of the following is NOT true of an action potential? A) Action potentia
ID: 148971 • Letter: 7
Question
7. Which of the following is NOT true of an action potential? A) Action potentials follow the all-or-none law. B) An action potential only starts when the depolarization reaches threshold C) A cell can not response to any stimulation when its membrane potential is beyond the threshold potential D) All cells in the body can produce action potentials 8. Which of the following neurons are found entirely within the central nervous system? A) Interneuron B) Ganglia. C) Motor neuron. D) Sensory neuron. 9. What mechanism causes the voltage-gated Na+ channels to close during an action potential? A) The activation gate is voltage sensitive and closes close to the equilibrium potential for Na+ B) The activation gate is sensitive to K+ and closes when its intracellular concentrations drop. C) The inactivation gate has a time-dependent closure. D) The inactivation gate is voltage sensitive and closes close to the equilibrium potential for Na+ 10. What is the benefit for neurons to have refractory period? 11. True or False. In order to response to stronger stimulation, the neurons will fire larger action potentials, such as increased action potential amplitude.Explanation / Answer
7. The answer is D.
An action potential is the rapid rise and fall of the membrane potentials.
An action potential is a property of several animal cells but it is not present in all the body cells. An action potential is present in some cells like neurons, muscle cells, cardiac cells, and some endocrine cells.
8. The answer is A.
Interneurons are present in the central nervous system only and they connect neuron to neuron.
Sensory neurons have the long dendrite and short axon and they transmit information from sensory organs to the central nervous system.
Motor neurons transmit information from the central nervous system to muscle cells.
ganglia are a cluster of nerve cells found in the peripheral nervous system.
9. The answer is D.
During the firing of action potential, the voltage-gated sodium channels open and there will be an inward flow of Na+ ions and it will depolarize the cell. At this point, the membrane becomes positively charged. After this, the sodium channels will be inactivated and this phase is called repolarization.
10. The refractory period is the time when a neuron cannot fire another action potential. It provides the advantage as it makes the neuron that just fired an action potential unresponsive and hence an action potential cannot be generated in the retrograde direction.
11. False. Action potential follows all or none phenomena. So if you apply a stimulus above the threshold it will fire the action potential but the stimulus will not affect the magnitude of action potential
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