discuss the steps involved in forming an action potential, starting with the opening of voltage-gated sodium channels
Ans. A nerve cell has separate ionization potential on both the intracellular fluid and extracellular fluid. This difference in potential is maintained by different concentrations of ions on the inside and outside of cell. The ions that have main contributions in creating this potential difference are sodium ions, potassium ions, chloride ions and bicarbonate ions. In the normal resting condition, there are more number of negative ions in the interior of the cell than the exterior. This action is accomplished by the sodium-potassium pump which extrudes 3 sodium ions outside the cells, while pumps 2 potassium ions inside the cell. This creates a concentration gradient of sodium ions with more number of sodium ions outside the cell than inside.
As a nerve receives stimulation, voltage gated sodium ion channels open. Due to high concentration difference of sodium ions between inside and outside the cell, sodium ions rapidly rush into the cell creating positive membrane potential within the cell compared to the outside. This condition is called depolarization. This shooting up of the membrane potential within the nerve cell upon stimulation is called action potential.
As the stimulation moves forward down the nerve cell towards the synaptic end, the front portion gets depolarized while the previous portion gets repolarized. Repolarization occurs by gradual inactivation of voltage gated sodium ion channels. Along with this, potassium leak channels also allow the exit of potassium ions out of the cell. This causes further fall in membrane potential within the nerve cell. This condition is called hyperpolarized state. During this stage, next stimulus is unable to excite the nerve cells again. After this stage, the nerve cell again returns back to its normal polarized state.
discuss the steps involved in forming an action potential, starting with the opening of voltage-gated sodium...
You are studying the permeability on Voltage-Gated Sodium Channels involved in action potential generation. Predict what would happen to the permeability of Sodium in the following cases (would it decrease, increase or stay the same?). Explain why you chose your answer. i.Increased receptor number. ii. Add a drug that make channel stay open longer. iii. Raise Vm above+35mV. iv.Lower Vm below -70mV. v.Add a drug that prevents channel opening. vi. Add more Na+ to the extracellular environment.
CNCORA 6 of 10 > Action potentials in neurons involve opening and closing of voltage-gated Nat and K ion channels. Place the events of an action potential in order, starting and ending with a cell at its resting membrane potential. Resting state Return to resting state Answer Bank A graded potential brings the membrane to threshold potential. Fast Na+ and slow K* channels are activated. Nat rushes into the cell, causing membrane depolarization. K channels close slowly, resulting in hyperpolarization....
An action potential does not move back wards in the axon because.. a.Voltage-gated sodium channels behind the action potential are inactivated. b. Potassium leak channels no longer let potassium ions through c. Voltage-gated sodium channels are open d. Mechanically-gated channels prevent outflow of sodium e. Voltage-gated potassium channels are closed
The plateau phase of the ventricular action potential is caused by O fast voltage-gated Ca2+ channels opening fast Nachannels opening O slow K* channels opening Oslow voltage-gated Ca2+ channels opening Submit Request Answer
3. Many neurons contain "delayed K channels". Like voltage-gated Nat channels, these voltage-gated K+ channels open in response to a rise in membrane potential and then undergo inactivation. However, opening of the voltage-gated K channels lags behind opening of the voltage-gated Na channels. a) Why does neuronal function require the voltage-gated K channels to open more slowly than the voltage-gated Na channels? b) Compared to a neuron that lacks voltage-gated K channels, what differences would you expect in the shape...
Ion channels are involved with generating action potentials. Below is an electrical profile of a neuronal action potential. In the boxes below list whether the channels are all open, all closed, opening, or closing at each of the letters shown in the profile. (Opening implies that channels were "all closed" and are moving toward their "all open" state. Closing indicates the opposite. Use the term "closing" to represent the inactivated state of the Na+ channels.) (7 pts) 1. Channel Type...
choices for A: Na+/K+ pumps, voltage gated K+ channels, voltage gated Ca+ channels, voltage gated Na+ channels choices for B: bidirectionally, unidirectionally choices for C: Na+/K+ pumps, voltage gated K+ channels, voltage gated Ca+ channels, voltage gated Na+ channels choices for D: Na+/K+ pumps, voltage gated K+ channels, voltage gated Ca+ channels, voltage gated Na+ channels Consider this graph illustrating the generation of an action potential across the plasma membrane of a stimulated neuron. +40 ACTION POTENTIAL plasma membrane potential...
The fixed pattern of changes in membrane potential during an action potential is coordinated by the sequential opening and closing of voltage-gated ion channels. Can you identify the status (open/closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential? Drag the appropriate labels onto the graph to indicate the status (open or closed) of the voltage-gated Na+ and K+ channels during each phase of an action potential. Labels may be used once, more than once,...
For each phase of an action potential, indicate the ion channel most responsible for the membrane potential change that occurs during the phase. Action Potential Phases Ion Channels Depolarization phase Repolarization phase Hyperpolarization phase Voltage-gated potassium channels Chemically-gated sodium channels Chemically-gated potassium channels Voltage-gated sodium channels
Action potentials do not occur in the soma of a neuron because a.it lacks voltage gated sodium channels b.it lacks leaky potassium channels c.it lacks leaky sodium channels d.it lacks chemically gated channels