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.

The resting membrane potential is established by?  The Na+/K+-ATPase pumping Na+ into the cell and K+ out of the cell  The Na+/K+-ATPase pumping K+ into the cell and Na+ out of the cell  A larger diffusion of K+ out of the cell compared to diffusion of Na+ into the cell  A larger diffusion of K+ into the cell compared to diffusion of Na+ out of the cell  a) and d)  b) and c)

Calculate the maximum ratio that can be achieved by the plasma membrane Na+-glucose symporter of an epithelial cell when [Na+]in is 12 mM, [Na+]out is 145 mM, the membrane potential is −50 mV (inside negative), and the temperature is 37 °C.

The resting membrane potential is a negative value because of:

When a cell membrane potential shifts from -70mV to -90mV we say the membrane has: depolarized repolarized hyperpolarized polarized GOOO0

Virtually all vertebrate cells, whether excitable or not, have a resting membrane potential (RMP).  please choose the right answer fro C1 C2 C3 and C4 C. Suppose you add enough KCl to increase the [K+] in the ECF from the usual value (3 mM) to 4.5 mM. What should happen to a neuron?    C-1. You expect the RMP to become (+ or more +) (- or more -) (less -) (less +) (go to, or stay at, zero) (stay at the normal nonzero value).   C-2. You expect the total number of K+ ions inside the cell to (increase) (decrease) (stay about the same).   C-3. You expect the net [K+] inside the cell -- in mM -- to (increase significantly) (decrease significantly) (stay about the same).   C-4. Suppose the neuron under consideration gets input from many different synapses. You increase the [K+] in the ECF as above. Given your answer to part C-1, the neuron should be (more likely) (less likely) (about equally likely) to fire an action potential. No explanation required on the exam, but it helps to see how you…

In the Nernst equation [V = 62 log10 (Co / Ci)], the term Co represents: cell bio  the intracellular concentration of calcium the extracellular concentration of potassium the extracellular concentration of sodium the intracellular concentration of potassium the membrane potential (in millivolts)

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.

Sodium (Na*) and Potassium (K+) are equally distributed across the neuronal membrane at resting membrane potential because of the: O Unassisted passive diffusion across the membrane O Nat/K+ Pump O Nongated Channels Voltage-gated Channels Chemically-gated Channels

Consider a typical mammalian neuron with all of the appropriate membrane channels. If you know that neuron is at rest, at a temperature of 37°C and you know the intracellular and extracellular concentration of the potassium, which of the following statements is most likely to be true? a. The equilibrium potential of potassium would be negative if the concentration of potassium is higher on the inside. b. The equilibrium potential of potassium would be positive if the concentration of potassium is higher on the inside c. The equilibrium potential of potassium cannot be calculated because the Nernst equation requires that you know the concentration of all ions d. The equilibrium potential of potassium be zero if the concentration of potassium is higher on the outside e. None of the above