An experimental cell line expresses K+ inward rectifier channels, Na+ leak channels, K+ channels activated by the elevated levels of cytosolic Ca2+, Cl- channels activated by PKC, aquaporins, and α-1 adrenergic receptors (GPCRs that activate Gαq/11 signalling pathway). No voltage-gated channels of any kind are present. The resting membrane potential of these cells is about –50 mV, and they are bathed in the standard extracellular solution. The intracellular concentrations of the relevant ions are as follows: K+ 130 mM, Na+ 15 mM, Cl- 30 mM, Ca2+ 10-4 mM.

An experimental cell line expresses K+ inward rectifier channels, Na+ leak channels, K+ channels activated by the elevated levels of cytosolic Ca2+, Cl- channels activated by PKC, aquaporins, and α-1 adrenergic receptors (GPCRs that activate Gαq/11 signalling pathway). No voltage-gated channels of any kind are present. The resting membrane potential of these cells is about –50 mV, and they are bathed in the standard extracellular solution. The intracellular concentrations of the relevant ions are as follows: K+ 130 mM, Na+ 15 mM, Cl- 30 mM, Ca2+ 10-4 mM.

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 1ITD: You learned in this chapter that Na+/K+ active transport pumps in the plasma membrane of the axons...

See similar textbooks

Similar questions

You learned in this chapter that Na+/K+ active transport pumps in the plasma membrane of the axons are responsible for creating the imbalance between Na+ and K+ inside and outside of the neuron that produces the resting membrane potential. In early research studying the role of ions and the involvement of active transport of ions in neural signaling, investigators used the giant axon of a squid as a model. The diameter of a giant axon is far greater than that of a mammalian axon, which enabled researchers to isolate it easily and use it in in vitro experiments. In one early experiment, researchers investigated the active transport of Na+ out of the axon in response to the presence of cyanide. Experimentally they hooked up a section of axon to a syringe, immersed the axon in artificial seawater, introduced radioactive 22Na (as 22NaCl) into the axon, and then quantified the transport of 22Na out through the axons plasma membrane. The rate of 22Na transport out of the axon was determined by measuring the radioactivity released into the fluid sur- rounding the axon over a period of time. The Figure shows the results of the experiment. What is the effect of cyanide on Na1 transport out of the squid axon? How do the data show the effect? Source: P. C. Caldwell et al. 1960. The effects of injecting energy-rich phosphate compounds on the active transport of ions in the giant axons of Loligo. The Journal of Physiology 152:561590. Cengage Learning 2017
Which of the following statements best describes the features of voltage-gated K+ channels? They consist of 4 subunits, are activated at the same time as voltage-gated Na+ channels, but do not inactivate. They consist of 4 subunits, are activated by depolarisation and close slowly during the refractory period. They have 24 membrane spanning alpha helices, 4 of which have positively charged amino acids which promote a conformational change in the channel following depolarisation. They consist of 4 subunits and are open at rest which causes the resting membrane potential to be close to the K+ equilibrium potential.
The membrane potential in animal cells, but not in plants, depends largely on resting K+ channels. How do these channels contribute to the resting membrane potential? Why are these channels considered to be nongated channels? How do these channels achieve selectivity for K+ versus Na+, which is smaller than K+?
The top panel (a) of this figure shows the graded potential change (far right, upper, electrical trace) that results from ligand binding to the ligand gated Na+ channel. The bottom panel of this figure (b) shows a graded potential change (far right, lower, electrical trace) that results from ligand binding to a ligand gated Cl- channel. From this trace you know (Vm = -70 mV) 1. ECl- is -70 mV 2. ECl- is more negative than -70 mV (i.e., -80 mV) 3. ECl- is more positive than -70 mV (i.e., -60 mV)
Name three features common to the activation of cytokine receptors and receptor tyrosine kinases. Name one difference with respect to the enzyme activity of these receptors.
Given the existence of leak channels for both K and Na , could the membrane repolarize C688 if the voltage-gated K channels did not exist?
Clostridium tetani toxin blocks the exocytosis of GABA. A. What anatomical part of a pre-synaptic neuron would be affected by this? B. How would a post-synaptic neuron’s likelihood of experiencing an action potential be affected by this toxin? C. Explain, using at least TWO of the following terms: threshold, depolarization, repolarization, hyperpolarization, summation, IPSP, EPSP, exocytosis
Why was the postsynaptic CA1 neuron voltage clamped to +30 mV? To stimulate insertion of AMPA receptors into the postsynaptic membrane To move NDA receptors into the synapse from an extrasynaptic site To cause coordination between the pre- and postsynaptic neuron To increase conductance of the NMDAR by removing the Mg?* block To stimulate AMPA receptors, which in turn activate NMDA Rs Explain the results obtained when AP5 was applied while the neuron was held at +30 mV. What is the interpretation of the result?
Compound X has been shown to block voltage-gated K+ channels with an IC50 of 0.1 mM. Which of the following is the most likely to occur in neurones following application of 0.03 mM X? Action potentials would be prolonged and the resting potential would be depolarised. Action potentials would be prolonged but the resting potential would remain the same. Neither resting potential nor action potentials would be affected because the concentration of X is less than the IC50 value. The resting membrane potential would depolarise but there would be no effect on action potentials.
Based on our discussions for different members of the K+ channel family (which include Kv, KCa, HCN/CNG, Kir, and K2P), which of the following can bind to K+ channels, enhancing activation? Ca++/calmodulin Cyclic nucleotides (cAMP, cGMP) PIP2 All of the above
Separately, draw a table using arrows to depict the appropriate magnitude and direction of the forces and ion fluxes at different membrane potentials for a ligand-gated channel that is equally permeable to both ion X+ and ion Y+. The equilibrium potential for ion X+ is -60 mV, and the equilibrium potential for ion Y+ is -20 mV. Which item best represents the forces and fluxes for a membrane potential of -60 mV? Pick one of the four tables in the included image please for your answer.
. which of the following statements about heterotrimetric G proteins and their receptors is incorrect? A: when GTP binds to the alpha subunit of the G protein, the beta-gamma subunit dissociates from the alpha subunit B: G-protein coupled receptors contain nine transmembrane alpha helices C: binding of arrestin causes removal of the receptor from the membrane D: G protein- coupled receptors may be desensitized by serine phosphorylation I had chosen option A and got it wrong. What is the Correct answer and explain how it is. Also, where did i go wrong in choosing option A?