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28 Cards in this Set
- Front
- Back
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What part of the neuron integrates the incoming signal?
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the axon hillock
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To activate a Na+ gated channel, the membrane potential must first be..
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depolarized to -55 mV
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To inactivate a Na+ gated channel, the membrane potential must first...
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depolarize all the way to +30
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In the cell membrane, the trigger zone is where you find...
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a ton of voltage gated Na+ channels
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When the trigger zone in the cell membrane becomes depolarized, this causes the cell to undergo an ______________, causing all other Na+ gated channels to depolarize.
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all-or-nothing action potential
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When sodium reaches the maximum depolarization membrane potential at __________, _________ have had enough time to fully open. Now that the channels are open, this ion moves (into/out) of the cell and makes the cell more (positive/negative).
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+30 mV
potassium channels -out -negative (once sodium depolarizes the cell to +30, potassium channels become fully open allowing potassium to leave the cell. As K+ leaves the cell, it becomes more negative. |
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When potassium leaves the cell AFTER depolarization, it makes the cell more (positive/negative) in a process called ______________.
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-negative
-hyperpolarization |
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Absolute refractory period?
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when a second action potential ABSOLUTELY CANNOT occur
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Relative refractory period?
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when a second action potential is possible but the threshold is elevated
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Hyperkalemic periodic paralysis is a channelopathy in which the...
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inactivation gate of Na+ voltage gated channels is altered (in muscles)--causes increased depolarization. Because potassium channels will be open until the cell hyperpolarizes, they will stay open for a long time and will make the ECF very hyperkalemic. This hyperkalemia weakens muscle contraction.
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Tetrodoxin (from blue-ringed octupuses/puffer fish), saxitoxin (dinoflagellates), muconotoxin affect the ________ channel.
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Na+ voltage gated
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What is the shunting power of Cl-??
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when Na+ or Ca2+ enter the cell during depolarization, making it more positive, Cl- also enters the cell (shunting) to counteract the cell from becoming too positive
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If the membrane potential of the cell is -100 and you send an input that activates Cl- channels, Cl- will move (into/out) of the cell, making the cell more _________. Why?
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-out
-positive because the resting potential of Cl- is near -76. |
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What kind of cells produce the myelin sheath?
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glial
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As an action potential travels down the axon, what prevents the potential from traveling backwards?
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the refractory period (absolute--when the Na+ inactivation gate is closed, relative--when potassium hyperpolarizes cell so you need to reach a higher threshold)
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The larger the axon diameter, the (faster/slower) the action potential propagates down its length.
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faster (like a HO'S)
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What are the glial cells in the peripheral nervous system called?
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schwann cells
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What are the glial cells in the CNS called?
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oligodendrocytes
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What are the areas between adjacent patches of myelination called?
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nodes of Ranvier
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How does the myelin sheath speed up conduction?
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the action potential jumps from one node of Ranvier to the next because only the nodes have voltage gated sodium channels. Opening the channels takes time, so the more myelin there is=the less channels the potential has to open and the more skipping from node to node occurs = faster. Also, the areas that are covered by the sheath are safe from the current leaking.
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Action potential conduction in myelinated axons is called
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saltatory conduction
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Under a micron, it is faster to have (myelinated/unmyelinated) axons.
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unmyelinated
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Leprosy, diptheria, Guillain-Barre syndrome, hereditary and sensory neuropathy and multiple sclerosis are all...
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myelination pathologies
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Graded potentials occur in the....
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dendrite
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Action potentials occur in the...
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axon
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Graded potentials are (summed/all or nothing) while action potentials are (summed/all or nothing).
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-summed
-all or nothing |
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Does a graded potential require a threshold stimulus?
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no. only action potentials
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Sodium and potassium are ions involved in (action potentials/graded potentials) while sodium, choloride and calcium are involved in (action potentials/graded potentials)?
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-action potentials
-graded potentials |
