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I have a question set from physiology practice problems:
Use the following information to answer the next 3 questions (1-3). You are studying a previously uncharacterized synapse in the central nervous system. You have determined that stimulating the presynaptic neuron releases a transmitter that opens Cl–-selective channels. Prior to stimulation, the postsynaptic cell’s resting potential is -80 mV and the Cl– equilibrium potential (ECl) is -50 mV.
1. Cl– is
a) concentrated inside the cell
b) concentrated outside the cell *** (This is correct)
c) evenly distributed about the membrane
d) not enough information provided to answer the question
2. When transmitter-gated Cl– channels open in the membrane, the cell will
a) depolarize*** (This is correct)
b) hyperpolarize
c) not change
3. During the synaptic response, Cl– will move
a) down its concentration gradient
b) up its concentration gradient*** (why?)
c) equally in both directions
Could someone explain for #3 why it would go up its concentration gradient? To me it seems counterintuitive, as opening up a channel that is Cl- specific should let Cl- flow down its concentration gradient... Yet this is the answer given in numerous problem sets.
Help?
Use the following information to answer the next 3 questions (1-3). You are studying a previously uncharacterized synapse in the central nervous system. You have determined that stimulating the presynaptic neuron releases a transmitter that opens Cl–-selective channels. Prior to stimulation, the postsynaptic cell’s resting potential is -80 mV and the Cl– equilibrium potential (ECl) is -50 mV.
1. Cl– is
a) concentrated inside the cell
b) concentrated outside the cell *** (This is correct)
c) evenly distributed about the membrane
d) not enough information provided to answer the question
2. When transmitter-gated Cl– channels open in the membrane, the cell will
a) depolarize*** (This is correct)
b) hyperpolarize
c) not change
3. During the synaptic response, Cl– will move
a) down its concentration gradient
b) up its concentration gradient*** (why?)
c) equally in both directions
Could someone explain for #3 why it would go up its concentration gradient? To me it seems counterintuitive, as opening up a channel that is Cl- specific should let Cl- flow down its concentration gradient... Yet this is the answer given in numerous problem sets.
Help?
