Opening of voltage-gated Na channels controls the _____ of an action potential.
ID: 3473275 • Letter: O
Question
Opening of voltage-gated Na channels controls the _____ of an action potential. A. Hyperpolarization B. Depolarization C. Repolarization D. Threshold At rest, the concentration of K is _____ outside of the neuron compared to the inside. A. Higher B. Lower C. Equal D. Zero The Na-K-ATPase pumps moves ____ out of the cell and _____ into the cell with each turn. A. 2 Na, 3 K B. 2 K, 3 Na C. 3 Na, 2 K D. 2K, 2 Na K is continually moving out of the cell _____. A. Through voltage-gated channels B. Through passive leak channels C. Down its concentration gradient D. B and C Voltage-gated ion channels are induced to open by: A. A change in membrane potential B. A change in temperature C. A change in mechanical stress D. A change in hydration Which is the correct order of the following events that occur at a synapse? 1. Arrival of action potential at presynaptic neuron terminal 2. Binding of neurotransmitter to receptors on postsynaptic membrane 3. Opening of voltage-gated Ca^2+ channels 4. Binding of vesicles of neurotransmitter with the membrane of presynaptic terminal 5. Depolarization of postsynaptic membrane A. 1, 3, 4, 2, 5 B. 1, 4, 3, 5, 2 C. 3, 1, 5, 2, 4 D. 3, 2, 1, 4, 5Explanation / Answer
1. Opening the voltage gated Na+ channels controls the depolarization of the membrane potential and lead the outward movement of the voltage sensors. Option B is correct answer.
2. At rest the concenteration K+ is lower outside of the neuron as compared to the inside & the concenteration gradient can cause be outward movement of K+ ions. Option B is correct answer.
3. The Na+ pottasium ATPase pump moves 3 Na+ out of the cell and 2K+ into the cell with each turn causing the increase in 'fuel' charge on external membrane and inner side become negative; polarization. Option C is correct answer
4. K+ is continuosly moving out of the via passive leak channels down the concenteration gradient . Hence option B & C are correct answer
5. Voltage gated ion channels are induced to open by a change in the membrane potential due to this change the ionsmove in and out of the cell. Option A is correct answer.
6. Events occuring at synapse are;
(i) Arrival of action potential at the presynaptic neuron terminal.
(ii) Opening of voltage gated Ca2+ channels.
(iii) Binding of the vesiclesof neurotransmitter to the membrane of presynaptic terminal .
(iv) Binding of neurotransmitter to the receptors of post synaptic membrane.
(v) Depolarization of post synaptic membrane. Hence the correct order is 1,3,4,2,5.Option A is correct answer.
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