sample_midterm_3_2007_key

sample_midterm_3_2007_key - Question 1 (10 points) Circle...

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Question 1 (10 points) Circle true or false. 1. ATP hydrolysis is used to propagate the action potential. (True/ False ) 2. Hyperpolarization can cause an action potential. (True/ False ) 3. Removing extracellular calcium prevents the generation of an action potential. (True/ False ) 4. Chemical synapses are faster and more common than electrical synapses (True/ False ) 5. Astrocytes can myelinate more than one axon. (True/ False ) Question 2 (26 points) You have set up an experimental system where you can record from a neuron that receives inputs from four other neurons as shown below. You have determined the ion concentrations inside and outside the cell. Inside the cell there is 10mM Na+, 10mM Cl-, and 100mM K+. Outside the cell there is 100mM Na+, 100mM Cl-, and 10mM K+. The resting potential for this neuron is –58mV and the threshold potential for this neuron is –40mV. LOGARITHMS CHEAT SHEET: Log(1000) = 3, Log(100) = 2, Log (10) = 1, Log (1) = 0, Log (0.1 ) = -1, Log (0.01 = -2, Log (0.001) = -3 GO ON TO NEXT PAGE! 1 2 3 4
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To do this you stimulate each presynaptic neuron and measure the reversal potential at each synapse. 2a. (2 points) What is the definition of reversal potential? Reversal potential is the potential at which there is not net flow of ions through an open channel. 2b. (2 points) How does one experimentally determine reversal potential? Patch clamp the cell at different potentials, measure postsynaptic currents. At reversal potential zero current will be measured. You find that the reversal potential for both synapses 1 and 3 is 0mV. For 2 it is –58mV and for 4 it is –10mV. 2c. (2 points) Which ion or combination(s) of ions could be responsible for the currents generated from stimulation of synapse 1? Na and K, or Na and Cl 2d. (2 points) Which ion or combination(s) of ions could be responsible for the currents generated from stimulation of synapse 2? K or Cl or both 2e. (4 points) Which of the 4 synapses are excitatory, and which are inhibitory? 1,3 and 4 are excitatory, 3 is inhibitory. The next experiment you do is to measure the post-synaptic membrane potential after stimulation of each presyanptic cell. 2f. (2 points) What is one neurotransmitter that could be released at synapses 1 and 3? Glutamate 2g. (2 points) What is another transmitter that could be released at synapses 1 and 3? ACh
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sample_midterm_3_2007_key - Question 1 (10 points) Circle...

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