Concept explainers
DRAW IT Suppose a researcher inserts a pair of electrodes at two different positions along the middle of an axon dissected out of a squid. By applying a depolarizing stimulus, the researcher brings the plasma membrane at both positions to threshold. Using the drawing below as a model, create one or more drawings that illustrate where each action potential would terminate.
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- A researcher conducts a voltage clamp experiment on a giant squid axon. She clamps a typical neuron at +52mV. In the graph on the right, draw out the current that she will most likely record at this voltage.arrow_forwardJose measures membrane potential in two neighboring cells. He notices that when the membrane potential changes in one cell, the membrane potential of the neighboring cell changes in a similar manner. For example, if one cell hyperpolarizes, the neighboring cell also hyperpolarizes. He concludes the cells are electrically coupled. Which of the following is the most likely to cause the electrical coupling? a.) The electrical coupling is most probably due to integrins that connect the two cells. b.) The electrical coupling is most probably due to tight junctions that connect the two cells. c.) The electrical coupling is most probably due to desmosomes that connect the two cells. d.) The electrical coupling is most probably due to gap junctions that connect the two cells.arrow_forwardWhich of the following describe(s) the difference(s) between an EPSP and an IPSP? Select all that apply. An EPSP is actively reproduced as it travels along the axon, whereas an IPSP is a graded potential that decreases in strength with time and distance. An EPSP moves the cell closer to threshold, whereas an IPSP moves the cell away from threshold. An EPSP results from the movement of Cl- ions into the cell, whereas an IPSP results from movement of Na+ ions into the cell. An EPSP is a result of depolarization of the cell membrane, whereas an IPSP is a result of hyperpolarization of the membrane.arrow_forward
- Repolarization is when the cell membrane potential becomes more positive the sodium channels open on the membrane the calcium channels open on the membranc the cell membrane potential becomes more negative.arrow_forwardPlease answer question 32arrow_forwardConsider a typical mammalian neuron with all of the appropriate membrane channels. If you know that neuron is at rest, at a temperature of 37°C and you know the intracellular and extracellular concentration of the potassium, which of the following statements is most likely to be true? a. The equilibrium potential of potassium would be negative if the concentration of potassium is higher on the inside. b. The equilibrium potential of potassium would be positive if the concentration of potassium is higher on the inside c. The equilibrium potential of potassium cannot be calculated because the Nernst equation requires that you know the concentration of all ions d. The equilibrium potential of potassium be zero if the concentration of potassium is higher on the outside e. None of the abovearrow_forward
- How can molecules pass through a closed gate such as in ligand-gated channel protein? Group of answer choices Receptor must receive pressure to open the gate. Receptor must receive electrical signals to open the gate. Receptor must receive signals or stimulus from the neurotransmitter to open the gate. The ligand-gated channel protein is always open, and it does need any stimulusarrow_forwardIn an experiment, the extracellular [Na+] surrounding a nerve cell was reduced from 145 to 45 mM. Which of the following is the most likely effect of this on action potentials? No action potentials would occur because the concentration of extracellular Na+ is too low. The membrane potential would become more negative so the threshold for action potential generation could not be reached. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarisation phase would be slower. The nerve cell would still produce an action potential but its amplitude would be reduced and the depolarization phase would be more rapid.arrow_forwardvoltmeter microelectrode electrode Giant squid axon A voltmeter was used to measure the potential difference across the cell membrane of a giant squid axon. Which of the following best explains the voltmeter reading? Select one: a. The threshold potential has not been reached. b. The sodium potassium exchange pumps are working to take out the sodium ions and bring in the potassium ions. c. The potassium ions have rushed out of the axon, and the potassium channels are slow to shut down. d. The sodium ions have rushed into the axon, and the sodium channels are closing.arrow_forward
- Biology: The Dynamic Science (MindTap Course List)BiologyISBN:9781305389892Author:Peter J. Russell, Paul E. Hertz, Beverly McMillanPublisher:Cengage Learning