MamPhys Exam 2 Questions And Answers With Verified Study Set The resting membrane potential (RMP) depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. (hint: there is one factor that sets up the concentration gradients of K+ and Na+: this factor is NOT directly responsible for the magnitude and sign of the RMP.The presence of concentration gradients and leak channels The membrane potential is defined as electrical disequilibrium between the ICF and the ECF (ions are not distributed evenly between the ECF and the ICF, especially across the membrane) At rest (in a resting neuron, so we're talking about the resting membrane potential), there is a little bit more ___ than ______ K+ efflux; Na+ influx The Na+/K+ pump transports ________.Na+ out of and K+ into the cell Potassium levels are ____ inside the cell than outside the cell higher The equilibrium potential of sodium is positive Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane in a cell at rest. What is the name given to this potential difference? (Hint: All cells exhibit an electrical potential difference across their plasma membranes. Only excitable cells can alter this difference by generating action potentials. Thus, an excitable cell, like a neuron, exhibits both a resting and an excited state).Resting membrane potential (RMP) The equilibrium potential of potassium is negative The plasma membrane of a resting neuron is much more permeable to K+ than to Na+. Why?There are many more K+ leak channels than Na+ leak channels in the plasma membrane.Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel?Leak channels The concentration gradient of potassium across the plasma membrane favors the ___ movement of potassium when more potassium channels open 1 / 2
outward (potassium is moving into the ECF) The electrical gradient is defined as a difference in the net charge between two regions The equilibrium potential is defined as the membrane potential that exactly opposes the concentration gradient of a certain ion at a given concentration gradient; at this point there is no net movement of that ion across the membrane The membrane potential at rest is negative
The resting membrane potential depends on each item below, EXCEPT:
the greater permeability of the membrane to anions rather than cations.Sodium levels are ____ inside the cell than outside the cell lower What prevents the Na+ and K+ gradients from dissipating?Na+-K+ ATPase pump The value of the resting membrane potential in a typical neuron is ________.-70 mV The concentration gradients for sodium and potassium between the ICF and the ECF are maintained by the ___ Na+/K+ ATPase pump The resting membrane potential results from uneven distribution of ions across the cell membrane and differences in membrane permeability to Na+ and K+.True or false? The equilibrium potential of Na+ is the membrane potential of a hypothetical cell that is very permeable to Na+ at a given concentration gradient. For Na+, the equilibrium potential is positive True The major determinant (because there are more leak channels for this ion) of the resting potential of all cells is K+ electrochemical gradient The concentration gradient of sodium across the plasma membrane favors the ___ movement of sodium when sodium channels open inward (sodium is moving into the cell) A neurotransmitter binds to a receptor, resulting in the opening of more potassium channels. How will this affect the membrane potential?it will become more negative than -70 mV (e.g. -80 mV) because with increased permeability to potassium, the membrane potential will be closer to the equilibrium potential of potassium (which is close to -90 mV)
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