Ion Kt + Na CI™ K Na+ CI Kt Nat CI™ Kt + Na CI Relative Permeability 10 1 10 1 10 Concentration (mm) Intracellular Extracellular Squid Axon with elevated extracellular [K*] 10 105 10 Squid Axon 400 50 50 10 1 10 400 50 50 Squid Axon with increased Na* conductance 10 20 440 560 400 50 50 Mammalian Neuron 140 10 10 90 440 560 20 440 560 5 145 110 Membrane Potential

A.What is the Result of the sodium potassium ATPase activity in the cell? B.What mechanism does the sodium potassium ATPase use to achieve this result? C. Why is the above-mentioned change in affinity critical for the sodium potassium ATPase to perform its function?

Explain why active transport of an ion shows saturation kinetics,whereas transport of an ion through an ion channel does not.

Compound X has been shown to block voltage-gated K+ channels with an IC50 of 0.1 mM. Which of the following is the most likely to occur in neurones following application of 0.03 mM X?     Action potentials would be prolonged and the resting potential would be depolarised.     Action potentials would be prolonged but the resting potential would remain the same.     Neither resting potential nor action potentials would be affected because the concentration of X is less than the IC50 value.     The resting membrane potential would depolarise but there would be no effect on action potentials.

Give typed full explanation

Three currents are produced by a 56 mV depolarization leading to an action potential in a squid axon membrane during a voltage clamp experiment as shown. What is the mechanism underlying the capacitive current? 56 mV Depolarization Capacitative current Late current Early current Time (ms) Opening of Na* channels Current due to the Na/K* pump O Neutralization of the charge on the membrane Opening of K channels Membrane Membeane current imA/cm potential (mV)

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.

If the resting membrane potential of a cell was +70 mV, the ELECTRICAL driving force on sodium would be:  Group of answer choices into the neuron out of the neuron balanced

A True OUTSIDE CELL This cell is at rest. False INSIDE CELL C D T E

Given a matrix pH of 7.8 and an inner mitochondrial membrane pH of 7.06, calculate the Nernst potential across the IMM in a lizard cell that is 27 degrees C.