ppose hdt Certain Cells lounu are shown below. The resting membrane potential is -75 mV. Assume that passage of both ions across the membrane occurs through ion channels that are selective for each ion Tno orie Test. The [Intracellular] [Extracellular] CI 4 mM 110 mM K+ 25 mM 100 mM Based on this information, what reasonable conclusion can you draw about the relative permeabilities of K+ and CI" ions in these neurons at rest based on what we discussed? O a. The membrane is more permeable to chloride ions than to potassium ions at rest. O b. The membrane is more permeable to potassium ions than to chloride ions at rest. C. At rest, the membrane potential of these neurons lies closer to the potassium equilibrium potential (EK) than it does to the chloride equilibrium potential (ECI). O d. Both a and c O e. Both b and c

ppose hdt Certain Cells lounu are shown below. The resting membrane potential is -75 mV. Assume that passage of both ions across the membrane occurs through ion channels that are selective for each ion Tno orie Test. The [Intracellular] [Extracellular] CI 4 mM 110 mM K+ 25 mM 100 mM Based on this information, what reasonable conclusion can you draw about the relative permeabilities of K+ and CI" ions in these neurons at rest based on what we discussed? O a. The membrane is more permeable to chloride ions than to potassium ions at rest. O b. The membrane is more permeable to potassium ions than to chloride ions at rest. C. At rest, the membrane potential of these neurons lies closer to the potassium equilibrium potential (EK) than it does to the chloride equilibrium potential (ECI). O d. Both a and c O e. Both b and c

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 2TAHL: Assume that a membrane permeable to Na+ but not to Cl- separates two solutions. The concentration of...

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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?
Describe the contribution of each of the following to establishing and maintaining membrane potential: (a) the Na+K+ pump, (b) passive movement of K+ across the membrane, (c) passive movement of Na+ across the membrane, and (d) the large intracellular anions.
Assume that a membrane permeable to Na+ but not to Cl- separates two solutions. The concentration of sodium chloride on side 1 is higher than on side 2. Which of the following ionic movements would occur? a. Na+ would move until its concentration gradient is dissipated (until the concentration of Na+ on side 2 is the same as the concentration of Na+ on side 1). b. Cl- would move down its concentration gradient from side 1 to side 2. c. A membrane potential, negative on side 1, would develop. d. A membrane potential, positive on side 1, would develop. e. None of the preceding is correct.
The equilibrium potential for a given ion (Eion) is a theoretical value. For a given concentration gradient of an ion, the equilibrium potential is the charge inside the cell required to hold an ion at that concentration. That is, it is the charge required to perfectly oppose the drive of the ion to move down its concentration gradient. So, if the concentration of Nat is higher outside the cell than inside, its equilibrium potential (ENa) must be I and if we add more sodium to the extracellular fluid, then ENa will II.
Calculate the equilibrium membrane potentials to be expected across a membrane at 37 ∘C, with a NaCl concentration of 0.50M on the "right side" and 0.08 M on the "left side", given the following conditions. In each case, state which side is (+) and which is (−). Membrane permeable only to Cl−.
Calculate the equilibrium membrane potentials to be expected across a membrane at 37 °C, with a NaCl concentration of 0.10 M on the “right side” and 0.01 M on the “left side”, given the following conditions. In each case, state which side is (+) and which is (-). (a) Membrane permeable only to Na+ (b) Membrane permeable only to Cl– (c) Membrane equally permeable to both ions
Considering this graph of membrane potential, what is most likely occurring during the period indicated by the green box?
Calculate the equilibrium membrane potentials to be expected across a membrane at 37 ∘C, with a NaCl concentration of 0.50 M on the "right side" and 0.08 M on the "left side", given the following conditions. In each case, state which side is (+) and which is (−). Membrane equally permeable to both ions.
Chloride ions (Cl-) behave a bit differently to Na+ and K+ in that most cells don't have active Cl- transporters. As a result, the concentration gradient for Cl- is not 'set' like it is for Na+ and K+. There are, however, a limited number of Cl- leak channels in the cell membrane. As a result, Eci generally matches resting membrane potential - around - 70mV. Considering this, answer the following questions. If Cl- can cross the cell membrane, is not being actively transported, and membrane potential is -70mV, will there be a concentration gradient for Cl-?
Assume that in a neuron, the plasma membrane permeability values for potassium (K+), sodium (Na+), and Cl− are the following: PK = 1, PNa = 12, and PCl = 0.5. Based on physiological concentrations of K+, Na+, and Cl− (refer to the table), determine the membrane potential in this neuron.
Batrachotoxin (BTX) is a steroidal alkaloid from the skin of Phyllobates terribilis , a poisonous Colombian frog (the source of the poison used on blowgun darts). In the presence of BTX, Na+ channels in an excised patch stay persistently open when the membrane is depolarized. They close when the membrane is repolarized . Which transition is blocked by BTX?
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 -20 mV?