BIO 467 Exam 1 Review Graded A 2025

1. You are studying a mammalian pyramidal neuron in an artificial CSF bath (4 mM K+, 135 mM Na+, and 100 mM Cl−) at 37 °C (310.15 K). It has intracellular [ion] of 140 mM K+, 5 mM Na+, and 20 mM Cl−. At rest, the neuron has relative permeabilities for K+, Na+, and Cl− of 1.00:0.05:0.45 (PK+:PNa+:PCl−). Its threshold potential is −45 mV. The primary neurotransmitter this neuron releases at its synaptic terminals is glutamate. This neuron receives both excitatory and inhibitory input from 7 other neurons. From the information above, calculate the neuron's resting membrane potential. - between -61 and -59 2. Which ion contributes the most to the resting membrane potential of our neuron? Why? - K+, the presence of K+ "leak channels" in the membrane 3. During a whole cell patch-clamp experiment, you would like to depolarize the resting membrane potential by 10 mV via adding a small amount of a concentrated ion solution (containing either Na+ or K+) to either the intracellular or extracellular compartment. During this procedure the relative permeabilities to each of the ions do not change. Which of the following changes in ion concentration can cause this modest depolarization? Select all of the correct answers. - Extracellular [Na+] increase and Extracellular [K+] increase 4. True or False. If you inject enough current into this neuron to drive the membrane potential to -30 mV, this neuron will fire an action potential that coincides with immediate Na+ influx and delayed K+ efflux. - True 5. Suppose we stimulate seven individual axons that provide either GABAergic or glutamatergic synaptic input to the neuron we are studying from question#1. Immediately following stimulation of each of the single axons, we record seven changes in the postsynaptic Vm relative to the resting membrane potential of our neuron: 10 mV 2. -11 mV 3. 14 mV 4. -8 mV 5. 9 mV 6. 5 mV 7. -10 mV We then re-stimulate all seven axons at the same time. Assuming the synapses are equal distances from the axon hillock, will the neuron generate an action potential as a result of this stimulation (Yes or No)? - no 6. In the question above (#5) you manually went through the process of determining the strength, location, and timing of inputs to determine if the neuron will generate an action potential. In neurons, we refer to this process as ? Select all the correct answers. - Spatial summation and temporal integration 7. Suppose the excitatory inputs from question #5 are glutamatergic and the inhibitory inputs are GABAergic. We add a drug to the aCSF bath and stimulated the neuron in the same way as in #5. This time, however, this stimulation caused the neuron to fire an action potential. Which of the following drugs could have caused this effect? Select all of the correct answers. - picrotoxin and kainic acid 8. When the neuron does fire an action potential, a family of voltage-gated ion channels that allow ions to flow across the membrane are primarily responsible for the rising phase of the action potential. - sodium 9. Which of the following mechanisms causes the rapid switch between depolarization and repolarization at the peak of the action potential? Select all of the correct answers. - Inactivation of the voltage-gated Na+ channels and Activation of the voltage-gated K+ channels 10. An action potential travels one way down the axon because of... - Inactivation of voltage-gated Na+ channels 11. During an action potential, there is a period of time when it is very difficult for the axon to generate another action potential known as the... - Refractory period 12. You decide to set up a whole cell patch clamp recording of the neuron. You instruct your patch-clamp rig to hold the current at 50 pAmps for 500 ms and record the response. What type of recording configuration would this be? - current clamp 13. To trigger an action potential, you ended up only requiring 30pA. If you then re-injected current only during the refractory period, which of the following levels of current would be most likely to stimulate the neuron to immediately fire another action potential? - 50pA 14. A poison dart frog escaped from the lab next door and contaminated your perfusion medium with the drug batrachotoxin. This results in 5 times the normal sodium permeability in the neuron you are recording from when at rest. What would be the new resting membrane potential of the neuron? - between -8 and -36 15. The new membrane potential following treatment with batrachotoxin is hyperpolarized relative to the original resting membrane potential. - false 16. You add tetraethylammonium (TEA) to the experimental chamber (assume the batrochotoxin has been washed out) and the resting membrane potential changes yet again. If we use a dose of TEA that reduces the permeability of its target by 50%, what will be the new resting membrane potential? - between -51 and -49 17. In vivo, the type of neuron you are recording from normally has a myelinated axon and a conduction velocity of 76 m/s. If the myelin sheath deteriorates due to disease, which of the following is likely the conduction velocity of the unmyelinated axon? - 10m/s 18. When the action potential reaches the presynaptic bouton, the opening of voltage-gated channels in the presynaptic membrane lead to the influx of ions required for synaptic vesicle release. - calcium 19. Which of the following events occur subsequent to the opening of the calcium ion channels - Synaptotagmin associates with the presynaptic membrane to facilitate vesicle fusion and Neurotransmitter is release into the synaptic cleft and Membrane fusion occurs 20. CREB phosphorylation downstream of the and pathways provides an example of intracellular signaling. - PKA, ERK1/2, convergent