portion of the graph labeled \"a\"? e been detected by the neuron ve been detect
ID: 281457 • Letter: P
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portion of the graph labeled "a"? e been detected by the neuron ve been detected by the neuron, causing openin 19. What is occurring at the portion of the graph 1 a. No neurotransmitters have been detert b. Some neurotransmitters have bee of some sodium channels. c. Threshold has been reached d. Voltage-gated potassium channels been reached beginning an action potential. ssium channels begin to open depolarizing the membrane aranh labeled "b", which of the following is more easily initiated because the neuron has 20. When the neuron is at the point in the graph label TRUE? a. A second action potential just fired an action potential. b. Voltage-gated sodium channels remain ced sodium channels remain open causing hyperpolarization The sodium potassium pump has restored resting potential It is difficult to fire another action potential because the cell is hyperpolarized. 21. À toxin that binds specifically to voltage-gated potassium channels in axons and inhibits them would be expected to a prevent the repolarization phase of the action potential b. prevent the depolarization phase of the action potential c. prevent the neuron from binding neurotransmitter molecules d. prevent the release of neurotransmitter molecules 22. An unusual form of a long neuron has one continuous myelin sheath down the length of the axon with no nodes of Ranvier. Which of the following do you expect to observe in this neuron? a. The action potential would be propagated nearly instantaneously to the synapse. b. There could be no binding of neurotransmitters at the dendrites. C. The axon membrane would not be able to depolarize. d. The release of neurotransmitters would be inhibited by Schwann cells. 23. Inhibitory neurotransmitters prevent the post-synaptic cell from firing an action potential. Which of the following could be a mechanism of how inhibitory neurotransmitters prevent an action potential? a. They do not require receptor proteins. b. They close potassium channels. c. They open sodium channels. d. They decrease the membrane potential. hape to the 24. Bisphenyl-A (BPA) is an endocrine disruptor th jis an endocrine disruptor that has a similar shape to the hormone estradiol. How do you expect BPA to act in the body. a. it stimulates production of estradiol b. it acts as a noncompetitive inhibitor of estradiol It binds to estradiol receptors and stimulates a cellulare d. it binds to estradiol and inhibits estradiol receptors ates a cellular responseExplanation / Answer
Answer 21. The correct answer is option A. Potassium channel blockers will prevent the repolarization phase of the action potential.
Voltage gated potassium channels are responsible for shift neurons from activated state to the resting potential. These channels shorten the refractory time of neurons to reach back to resting potential (-70mV). This will lead to blockage of sodium-potassium pump and thereby sodium will not be able transported across the neuron through this pump, rather it will diffuse. Therefore, it would take greater time for neuron to reach resting membrane potential, or in other words will prevent neuronal depolarization.
Answer 22. The correct answer for this question is option A.
Myelin sheath act as an insulator for the signals being conducted through the neurons, and thereby, it prevents weakening of signal due to loss of ions or electric impulse. Therefore, if there is a neuron covered entirely by myelin sheath, the signal will be transferred to the end instantly without any loss (which usually occur at the node of Ranvier where myelin sheath is not present under normal conditions). At the end of neuron, there will be dendrites and neurotransmitters will definitely bind at the synapse.
Answer 23. The correct answer for this question is option D.
Inhibitory neurotransmitters, like GABA, hyperpolarize the membrane i.e. they reduce the resting membrane potential beyond -70 mV. In such situation, neurons cannot reach the action potential and fail to fire. These neurotransmitters generally open chloride channels which reduces resting membrane potential to < -70 mV.
Answer 24. Correct answer to this question is option C.
BPA is having similar shape as of estradiol. Then it is expected that it would bind to the estradiol receptor and stimulate the downstream signaling as initiated by the estradiol. Receptors are having a receptor binding sites to which specific ligand binds. These sites can be used by the molecules which are structurally like parent ligand and thereby the signaling is activated. However, the intensity of signals generated may vary.
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