3) You are investigating the ionic selectivity of an ion channel opened by activation of a specific group ofionotropic receptors. You use the ionic concentrations shown in the following table and determine thatthe reversal potential for activation of the receptors is -10 mV?IonIntracellular (mM)Extracellular (mM)Equilibrium Potential (E1on)K+1405Na+10145Ca2+0.00012Cl-6.106a) Use the Nernst equation to calculate the equilibrium potential for each ion above.b) Is it likely that ion channel is selective to a single ion? Why or why not?c) Provide one possible ionic selectivity for this channel that could give rise to the following reversalpotential.d) How would you determine if this possibility is correct?

A. E(K+)= RTnFlnOUTIN=8.314×2981×96485ln5140=-0.089≈-89mV…

3) You are investigating the ionic selectivity of an ion channel opened by activation of a specific group of ionotropic receptors. You use the ionic concentrations shown in the following table and determine that the reversal potential for activation of the receptors is -10 mV? Ion Intracellular (mM) Extracellular (mM) Equilibrium Potential (Eton) K+ 140 Na+ 10 145 Ca2+ 0.0001 2 Cl- 6. 106 a) Use the Nernst equation to calculate the equilibrium potential for each ion above. b) Is it likely that ion channel is selective to a single ion? Why or why not? c) Provide one possible ionic selectivity for this channel that could give rise to the following reversal potential. d) How would you determine if this possibility is correct?

3) You are investigating the ionic selectivity of an ion channel opened by activation of a specific group of ionotropic receptors. You use the ionic concentrations shown in the following table and determine that the reversal potential for activation of the receptors is -10 mV? Ion Intracellular (mM) Extracellular (mM) Equilibrium Potential (Eton) K+ 140 Na+ 10 145 Ca2+ 0.0001 2 Cl- 6. 106 a) Use the Nernst equation to calculate the equilibrium potential for each ion above. b) Is it likely that ion channel is selective to a single ion? Why or why not? c) Provide one possible ionic selectivity for this channel that could give rise to the following reversal potential. d) How would you determine if this possibility is correct?

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter3: The Plasma Membrane And Membrane Potential

Section: Chapter Questions

Problem 2SQE: One of the important uses of the Nernst equation is in describing the flow of ions across plasma...

See similar textbooks

Similar questions

One of the important uses of the Nernst equation is in describing the flow of ions across plasma membranes. Ions move under the influence of two forces: the concentration gradient (given in electrical units by the Nernst equation) and the electrical gradient (given by the membrane voltage). This is summarized by Ohms law: Ix=Gx(VmEx) which describes the movement of ion x across the membrane. I is the current in amperes (A); G is the conductance, a measure of the permeability of x, in Siemens (S), which is I/V;Vm is the membrane voltage; and Ex is the equilibrium potential of ion x. Not only does this equation tell how large the current is, but it also tells what direction the current is flowing. By convention, a negative value of the current represents either a positive ion entering the cell or a negative ion leaving the cell. The opposite is true of a positive value of the current. a. Using the following information, calculate the magnitude of Na [ Na+ ]0=145mM,[ Na+ ]i=15mM,Gna+=1nS,Vm=70mV b. Is Na+ entering or leaving the cell? c. Is Na+ moving with or against the concentration gradient? Is it moving with or against the electrical gradient?
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 -40 mV (a, b, c, or d)? Upwards arrows means outward direction and downwards arrow means inward direction. The length of the arrow determines the magnitude.
The ion flows across neuronal membranes at rest and duringan action potential do not significantly change bulk ionconcentrations, except for that of Ca2+ ions. Resting Ca2+ ionconcentrations in cells are usually about 10–7 M, and Ca2+ ionsexert physiological effects at concentrations of perhaps 10–5 M.Explain why relative changes of intracellular [Ca2+] are muchgreater than for, say, [Na+] (12–50 mM).
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 (a, b, c, or d) best represents the forces and fluxes for a membrane potential of +20 mV? Upwards arrows means outward direction and downwards arrow means inward direction. The length of the arrow determines the magnitude.
a) Explain in detail what is occurring at stage A in the graph. (Be specific in terms of what's happening to the ion channels in your explanation if necessary!) b) What does this graph represent as a whole? Explain the main idea it portrays. +40| -70- A 1 2 4 Time/ms Potential Difference/mV B
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 -40 mV?
Both rhodopsin in vision and the muscarinic acetylcholine receptor in cardiac muscle are coupled to ion channels via G proteins. Describe the similarities and differences between these two systems.
At the peak of the action potential, Vm is approximately -65 mV. Assuming normal intracellular and extracellular K+ concentrations (refer to the table), (1) calculate the driving force (in mV) that acts on K+ ions and (2) use the information obtained in part 1 to determine the direction in which K+ ions will flow (i.e., into the cell or out of cell)
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.
37.Given an intracellular concentration of 120mM and an extracellular concentration of 15mM, calculate the Nernst Equilibrium Potential for K+ in mV 38 Given an intracellular concentration of 2mM and an extracellular concentration of 107mM, calculate the Nernst Equilibrium Potential for Cl- in mV 39 A cell has an actual membrane potential (Em) at rest of -75mV. The equilibrium potential for Na+ is +120mV and the equilibrium potential for K+ is -95mV. Calculate the net driving force for Na+ in mV.
Patch clamp recording of a single ion channel yields the following results: Holding Potential (mV) Measured Current (pA) -100 -1.0 -50 0.0 0 +1.0 +50 +2.0 +100 +3.0 part a.) Calculate the membrane potential at the instant when a neuron has the following relative permeabilities: PK+ = 1.0, PNa+ = 1.0, PCl- = 1.0. Use the ionic concentration values in the picture included. a.) -12 mv b.) -35mv c.) -60 mv d.) +20 mv e.) 0 mv part b.) What would be the equilibrium potential for K+ in neurons under such circumstances? a.) -11 mv b.) +30 mv c.) +75 mv d.) -35 mv e.) 0 mv part c.) What would be the new resting potential, discounting the effects of non-gated chloride channels (just give an approximate value – no calculation is necessary)? a.) about +20 to +25 mV b.) about -30 to -40 mV c.) about +1 to +5 mV d.) close to ENa+ e.) about -10 to -15 mV
Intracellular potentials are on the order of -100mV, whereas extracellular potentials are OmV. Assuming these values, answer the following questions. (a) What is the electric potential energy of a chloride ion (CI-) inside a cell? (b) What about outside the cell? (c) What is the probability of finding a Cl- inside the cell relative to finding it outside the cell? Assume that T=310K. P(inside) P(outside) (d) If the concentration of Cl- outside the cell is 100mM, what is the expected concentration inside the cell?