Figure 1 shows the action potential graph recorded from a rat neurone and the potential changes obtained from the rat neurone when the concentration of potassium ([K*]out) and calcium ([Ca²+]out) are varied extracellularly in the bathing solution. (i) In the resting state, is the neuronal permeability to potassium more than, less than or equal to that of the permeability to calcium? Explain your answer. (ii) Vm 'The calcium ion concentrations are lower inside the cell than outside.' Justify this statement based on the graphs and the Nernst equation assuming the temperature is at 25 °C. Vm 30 0 -30 30 0 -30- 50 AP overshoot [K+ lout 100 150 time (msec) 30 RP Figure 1 0 -30 AP overshoot RP 200 250 AP overshoot [Ca²+ lout RP

Figure 1 shows the action potential graph recorded from a rat neurone and the potential changes obtained from the rat neurone when the concentration of potassium ([K*]out) and calcium ([Ca²+]out) are varied extracellularly in the bathing solution. (i) In the resting state, is the neuronal permeability to potassium more than, less than or equal to that of the permeability to calcium? Explain your answer. (ii) Vm 'The calcium ion concentrations are lower inside the cell than outside.' Justify this statement based on the graphs and the Nernst equation assuming the temperature is at 25 °C. Vm 30 0 -30 30 0 -30- 50 AP overshoot [K+ lout 100 150 time (msec) 30 RP Figure 1 0 -30 AP overshoot RP 200 250 AP overshoot [Ca²+ lout RP

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter39: Information Flow And The Neuron

Section: Chapter Questions

Problem 5TYK: The major role of the Na+/K+ pump is to: a. cause a rapid firing of the action potential so the...

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Action potentials occur when ______. a. potassium gates close b. a stimulus pushes membrane potential to threshold c. sodium-potassium pumps become active d. neurotransmitter is reabsorbed
Conformational changes in channel proteins brought about by voltage changes are responsible for opening and closing Na+ and K+ gates during the generation of an action potential. (True or false?)
Answer the following questions regarding conduction of action potentials using the velocities given on p. 100: a. How long would it take for an action potential to travel 0.6 m along the axon of an unmyelinated neuron of the digestive tract? b. How long would it take for an action potential to travel the same distance along the axon of a large myelinated neuron innervating a skeletal muscle? c. Suppose there were two synapses in a 0.6 m nerve tract and the delay at each synapse is 1 msec. How long would it take an action potential and chemical signal to travel the 0.6 m now, for both the myelinated and unmyelinated neurons? d. What if there were five synapses?
Figure 35.11 Potassium channel blockers, such as amiodarone and procainamide, which are used to treat abnormal electrical activity in the heart, called cardiac dysrhythmia, impede the movement of K+ through voltage-gated K+ channels. Which part of the action potential would you expect potassium channels to affect?
Watch this video (http://openstaxcollege.org/l/summation) to learn about summation. The process of converting electrical signals to chemical signals and back requires subtle changes that can result in transient increases or decreases in membrane voltage. To cause a lasting change in the target cell, multiple signals are usually added together, or summated. Does spatial summation have to happen all at once, or can the separate signals arrive on the postsynaptic neuron at slightly different times? Explain your answer.
The major role of the Na+/K+ pump is to: a. cause a rapid firing of the action potential so the inside of themembrane becomes momentarily positive. b. decrease the resting membrane potential to zero. c. hyperpolarize the membrane above resting value. d. cause an action potential to enter a refractory period. e. maintain the resting membrane potential at a constantnegative value.
Dendrotoxins, produced by the mamba snakes (Dendroaspis), are inhibitors of the voltage-gated K+ channels. What phase of the action potential would this toxin affect? How would it affect ion permeability during this phase? How would ion movement be affected?
In 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.
dendrotoxins, produced by the mamba snakes are inhibitors of the voltage gated k+ channel. what phase of the action potential with this toxin effect? how would it affect ion permeability during this phase howard ion movement be affected?
A muscle cell contains acetylcholine receptors that act as ligand-gated cation channels,and it also contains voltage-gated Na+ channels of the type found in neurons. Intheory, could a muscle cell get away with having only acetylcholine-gated cationchannels, which would serve the dual purpose of receiving neurotransmitter signalsand propagating action potentials? Why or why not?
Describe the contribution of each of the following to the establishment and maintenance of membrane potential: Part A Na+K+ Pump Passive movement of K+ across the membrane Passive movement of Na+ across the membrane Part B Resting membrane potential is approximately -70mV. Explain what resting membrane potential is and what -70mV refers to.
Suppose that gated ion channels for Na+or Ca2+ opened in the plasma membrane of a muscle cell.The membrane potential of that cell would a. move toward the equilibrium potential for that ion. b. become less negative than the resting membrane potential. c. move farther away from the potassium equilibrium potential. d. all of these.