Choose the correct answer: A) When the voltage gated K+ channels open K+ moves down its concentration gradient from the ECF to inside the cell. B) The value for resting membrane potential is closer to the EK+ (Equilibrium potential for K+) than the ENa+ C) When the membrane potential is at rest the membrane is more permeable to Na+ than it is to K+ D) Closing of the voltage-gated Na+ channels increases the permeability of the

Choose the correct answer: A) When the voltage gated K+ channels open K+ moves down its concentration gradient from the ECF to inside the cell. B) The value for resting membrane potential is closer to the EK+ (Equilibrium potential for K+) than the ENa+ C) When the membrane potential is at rest the membrane is more permeable to Na+ than it is to K+ D) Closing of the voltage-gated Na+ channels increases the permeability of the

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 7UC: Describe the contribution of each of the following to establishing and maintaining membrane...

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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?
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?)
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.
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?
What properties of ion channels allow them to generate the large, rapid changes in membrane potential?
If a particular neuron has an intracellular Chloride concentration of 154.3 mM, an extracellular Chloride concentration of 163.2 mM, and a membrane potential of -54.1, what is the net driving force (in mV) acting upon Chloride?
if an object b has a plasma sodium concentration of 135mOsm/L and an intracellular concentration of 4mOsm/L. It also has a plasma concentration of potassium of 20mOsm/L and an intracellular concentration of 200mOsm/L. studies identify that the cells have a permeability to potassium that is 10 times greater than sodium. What is the resting membrane potential
If a cell with the following ion concentrations had a resting membrane potential of -40mV which of the following can you conclude? Extracellular: Cl- = 110 mM, Na+ = 145 mM, K+ = 5mM. Intracellular Cl- = 20 mM, Na+ = 10 mM, K+ = 140mM a) At rest it is only permeable to potassium b) At rest it has some permeability to more than one of these ions c) At rest it is only permeable to chloride d) Rest it is not permeable to sodium
The resting membrane potential…A) Can be approximated using the Goldman-Hodgkin-Katz equation.B) Represents a difference in charges across the cell membrane, resulting mostly from the passive flow of Na+ions.C) Has no influence on the driving force that acts on different ions across the cell membrane.D) Is equally dependent on the concentration gradients of potassium and sodium across the cell membrane.E) Becomes hyperpolarized during an excitatory graded potential.
Similarly, what will be the effect on membrane potential if Cl- ions move into a cell?
If the equilibrium potential for K* is -90mV, and the charge inside the cell is -70mV, which direction will K move across the membrane assuming there is permeability (membrane leak channels) which allow it to pass?
Which two factors involving ion diffusion determine the magnitudeof the resting membrane potential?