After an action potential has been initiated, there are two processes that prevent the membrane from remaining depolarized forever. What are these two processes? activation of ligand-gated channels activation of the Na/K pump activation of voltage-gated K+ channels activation of voltage-gated Na+ channels inactivation of ligand-gated channels inactivation of the Na/K pump inactivation of voltage-gated K+ channels O0000 0 O

What is the intracellular voltage for Cl- if the intracellular concentration was 5 mM and the extracellular concentration was 130 mM. Write the voltage as a number in mV inside the cell relative to that outside, eg. -72 or + 90. Question 2. What is the intracellular voltage for Ca++ if the intracellular concentration was 0.0008 mM and the extracellular concentration was 0.6 mM. Write the voltage as a number in mV inside the cell relative to that outside, eg. -72 or +90. Round to the nearest milli Volt.

13) Draw a graph representing the changes in membrane potential across the axonal membrane before, during, and after an action potential. On your graph, use a highlighter to clearly indicate for which portions of your graph the letter corresponding to each cellular event listed below belongs. List of cellular events: A) All K* channels open B) All Na* channels close C) The Na*/K* ATPase cotransporter transports Na* and K* across the membrane. D) All Na* channels open E) The threshold value of membrane potential is attained. F) All K* channels close G) Some Na* channels open Your graph:

Depolarization phase      --Click to select--   Chemically-gated potassium channels   Chemically-gated sodium channels   Voltage-gated potassium channels   Voltage-gated sodium channels     Repolarization phase      --Click to select--   Voltage-gated potassium channels   Voltage-gated sodium channels   Chemically-gated sodium channels   Chemically-gated potassium channels     Hyperpolarization phase      --Click to select--   Voltage-gated sodium channels   Chemically-gated potassium channels   Voltage-gated potassium channels   Chemically-gated sodium channels

If: membrane potential=-70mV, ENa=+60mV, and Ex=-90mV, consider which directions Na+ and K+ will leak across the membrane. If both ions are crossing the membrane, what is the most important factor in determining whether membrane potential will become more positive or more negative?

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.

What is the difference between a ligand-gated channel (like H1 or the AChR) and a voltage gated channel?

If action potential propagation from one neuron to another neuron requires ACh release, what event at the synaptic cleft explains the need for action potentials to arrive at a high rate before the post-synaptic membrane achieves threshold? the lack of sodium voltage gated channels on the post-synaptic membrane O the rapid breakdown of ACh by ACHE at the synaptic cleft the slow release of ACh by the synaptic vessicles the slow movement of sodium through chemical gates Previous Next MacBook Air

Place the following events in chronological order from 1-8: Nat enters the cell, and depolarization occurs to approximately +30 mV. The voltage across the cell membrane is -70 mV, the resting membrane potential. Upon reaching the peak of the action potential, the VG Nat channels are inactivated by the closing of their inactivation gate and the activation gate of each VG K channel opens. VG K channels close by the closing of their activation gate, and the resting membrane potential is gradually restored. An excitatory post-synaptic potential depolarizes the membrane to threshold and the activation gate of VG Nat channels open. Upon returning to the resting membrane potential, VG Na channels are reset by opening of the inactivation gate and the closing of the activation gate. VG K+ channels are slow to close, resulting in an excess of K* efflux and hyperpolarization. Depolarization occurs as K+ flows out of the cell.

What type of synaptic potential (if any; be sure to indicate if any modification is occurring as well) would occur if: a.) An MAO inhibitor type of antidepressant is functioning at an active dopaminergic synapse that increases the rate of sodium flowing into the cell. b.) Prozac is present at an active serotonin synapse where receptor activation increases the flow of potassium out of the cell.