Membrane potential in cells is constantly fluctuating. These fluctuations are called graded potentials and we will learn more about them in future lectures. Look at the fluctuating graded potential in the graph as an example. www If Cl generally has a relatively low membrane permeability, how would increasing CI permeability affect this graph? O The fluctuations in membrane potential would become more pronounced (i.e. higher peaks and lower troughs). O The fluctuations in membrane potential would become smaller. O There would be no change to these fluctuations as they are determined by Na+ and K+, not Cl-. O Membrane potential would stay at a constant -70mV.

Membrane potential in cells is constantly fluctuating. These fluctuations are called graded potentials and we will learn more about them in future lectures. Look at the fluctuating graded potential in the graph as an example. www If Cl generally has a relatively low membrane permeability, how would increasing CI permeability affect this graph? O The fluctuations in membrane potential would become more pronounced (i.e. higher peaks and lower troughs). O The fluctuations in membrane potential would become smaller. O There would be no change to these fluctuations as they are determined by Na+ and K+, not Cl-. O Membrane potential would stay at a constant -70mV.

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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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.
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.
What is the most important thing, i.e. what has the biggest impact of determining the resting membrane potential of a cell?
The reason that resting membrane potential (RMP) is closer to the equilibrium potential of K+ (EK) rather than that of Na+ (ENa) is that… Group of answer choices -The driving force for Na+ ions at rest is high. -The membrane is much more permeable to Na+ ions than K+ ions at rest. -Only K+ ions have a concentration gradient, Na+ ions have approximately equal intracellular and extracellular concentrations -The membrane is much more permeable to K+ ions than Na+ ions at rest.
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 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.
An analog of cGMP, 8-Br-cGMP, will permeate cellular membranes, is only slowly degraded by a rod cell’s PDE activity, and is as effective as cGMP in opening the gated channel in the cell’s outer segment. If you suspended rod cells in a buffer containing a relatively high [8-Br-cGMP], then illuminatedthe cells while measuring their membrane potential, what would you observe?
Suppose you inactivated a neuron’s Na/K exchange pumps (the active transporters), then immediately stimulated the neuron. Would the cell’s ability to respond to a second stimulus be changed? Explain briefly
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.
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
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.