The condition is known as hyperpolarization which happens because the equilibrium state of potassium makes the -90 once it comes around that -90 the net movement of potassium becomes 0 thus it will not more hyperpolarize than -90.
5. Did you notice that during the action potential the neuron membrane potential reaches -90mV and...
2. Neuron during an action potential: a. What triggers the first action potential (which ion)? b. What is the typical threshold potential of a neuron? c. The calculated equilibrium potential of Na+ (EN) is approx. +60mV (calculated). Explain how this is related to the rising phase of an action potential (depolarization). d. The calculated equilibrium potential of K+ (EK) is approx. -90mV. Explain how this is related to the falling phase (repolarization). e. Direction of Nation movement (influx/efflux). f. Direction...
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,...
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...
The peak of an action potential reaches +30 mV. This is because a. all of the available Na+ voltage activation gates are open b. all of the K+ voltage-gated channels open c. of the absolute refractory period d. of the decreased Na+ concentration gradient e. all of the available Na+ voltage inactivation gates are closed
During the propagation of an action potential, what would be the effect of a mutation in the voltage-gated Na+-channels that does not allow “inactivation” phase to occur, such that these channels go directly from open to closed conformations? a) The neuron with the mutant Na+ channels will start letting in calcium ions and generate a calcium-based action potential that is stronger than the sodium-based action potential. b) The neuron with the mutant Na+ channel will exhibit a reverse electrochemical gradient...
During an action potential, which of the following actions does not help return the membrane to its resting potential? Choose one: O A. the inactivation of voltage-gated Nat channels O B. the opening of voltage-gated K+ channels O C. the opening of voltage-gated Nat channels O D. the flow of K+ through K+ leak channels
This time you get into a snail brain neuron that is completely quiet. The cell doesn't even begin to fire action potentials when you inject depolarizing current, so you question yourself if you are actually in a neuron. Nevertheless, you briefly hyperpolarize thecell, and right after the hyperpolarization stops, the cell fires a few action potentials that have a quite large amplitude and then the cell becomes quite again. What could be going on here? Your traces kind of look...
QUESTION 8 he membrane potential becomes more negative than the resting potential during the after-hyperpolarization phase of the action potential (AHP) because Ligand-galed Nat channels are inactivated and cannot be opened Voltage-gated K channels become inactivated The K equilibrium potential is below the resting membrane potential All ofthe above. None of the above QUESTION 9 When an action potential reaches the axon terminal, release of neurotransmitter is triggered by... a. movement of sodium ions into the axon terminal b. movement...
Lo 10: Electrochemical Gradient The difference in voltage across the membrane is called the __________________________________. The inside of a normal cell is ___________________ (+/-); while the outside is ___________(+/-). The resting membrane potential of a neuron is ___________mV. Diagram the relative ratios of Ca++, Na+ and K+ in a cell under resting conditions. Draw an arrow for each of the molecules indicating which direction would be passive transport (into or out of the cell). For each of the following sentences, fill in...
In its resting state, the membrane surrounding a neuron is permeable to potassium ions but only slightly permeable to sodium ions. Thus, positive K ions can flow through the membrane in an attempt to equalize K concentration, but Na ions cannot as quickly. This leads to an excess of Na ions outside of the cell. If the space outside the cell is defined as zero electric potential, then the electric potential of the interior of the cell is negative. This...