Draw the current changes caused by a single voltage gated Potassium channel when the membrane is voltage-clamped at different voltage values (see below). Assume an equilibrium potential for potassium of -70mV and don't worry about exact values for the currents (approximations are fine). Label the axes on the traces and describe how the dynamics of individual voltage gated potassium channels come together to form the macroscopic K+ currents during depolarization.. a. @Resting Membrane Potential = -70 mV b. @Voltage Step = -20 mV c. @Voltage Step = +50mV

Draw the current changes caused by a single voltage gated Potassium channel when the membrane is voltage-clamped at different voltage values (see below). Assume an equilibrium potential for potassium of -70mV and don't worry about exact values for the currents (approximations are fine). Label the axes on the traces and describe how the dynamics of individual voltage gated potassium channels come together to form the macroscopic K+ currents during depolarization.. a. @Resting Membrane Potential = -70 mV b. @Voltage Step = -20 mV c. @Voltage Step = +50mV

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...

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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?
The membrane potential for an excitable cell membrane is -70 mV, for sodium ions the Nernst equilibrium potential is +50 mV, the conductivity of the single sodium channel is 10 pS. What is the electrochemical potential difference that is the driving force for sodium ions to migrate? How much current flows through an open sodium channel under these conditions?
Describe the action potential in terms of the different functional states of the voltage- gated Na+ membrane channels (Note: there are three states)
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)
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 (−). (a)Membrane permeable only to Na+.
With regard to Na+ and K+ equilibrium potentials and the resting and active membrane potentials, write down (a- D the directions of the forces indicated, acting on the ion in the table below under the respective condition(s). NB the examples given. lon Condition Electrical/Chemical force Direction of force Chemical e.g....inward.. ****** Na ENa+ = + 60 mV Electrical a. Chemical e.g. ...outward.. EK+ =- 90 mV Electrical b. Chemical C. Na" Emp = 0 mV Electrical d. Chemical K+ Emp =-20 mV Electrical
The concentration of potassium ions inside a nerve cell membrane is higher than the concentration of sodium ions outside the mem-brane, yet the inside of the membrane (where the cation concentra-tion is higher) is negative to the outside. Explain this observation in terms of permeability properties of the membrane.
Define electrochemical gradients and the term “polarized”, and describe the electrochemical basis of the resting membrane potential including the function of the sodium-potassium pump in maintaining the resting membrane potential.
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 following concentrations of Na+ and K+ ions: [Na+]o = 120 mM, [Na+]i = 6 mM,[K+]o = 2 mM, and [K+]i = 150 mM. Assuming that the further at the peak of the action potential, PK: PNa is 1 : 12. Calculate (Vm) at the peak of the action potential
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.
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?