PEX-03-09 - Physio Ex 9.1 PDF

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Physio Ex 9.1...

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Name: Steffany A. Rivera Exercise 3: Neurophysiology of Nerve Impulses: Activity 9: The Action Potential: Putting It All Together Lab Report Pre-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1. Sensory neurons respond to an appropriate sensory stimulus with a change in membrane potential that is You correctly answered: b. graded with the stimulus intensity. 2. If the depolarization that reaches the axon is large and suprathreshold, the result in the axon is You correctly answered: c. action potentials at higher frequency. 3. At the axon terminal, each action potential causes the release of neurotransmitter. This neurotransmitter diffuses to the receiving end of an interneuron, where it binds to receptors and causes You correctly answered: a. ion channels to open, so that the receiving end of the interneuron depolarizes. 4. Interneurons respond to chemical (neurotransmitter) stimulation with a change in membrane potential that is You correctly answered: b. graded with the stimulus intensity.

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Experiment Results Predict Question: Predict Question 1: If you apply a very weak, subthreshold stimulus to the sensory receptor Your answer : b. a small, depolarizing response will occur at R1, an action potential will occur at R2, and no responses will occur at R3 and R4. Predict Question 2: If you apply a moderate stimulus to the sensory receptor Your answer : a. a larger, depolarizing response will occur at R1, and an action potential will be generated at R2 and maybe at R4. Predict Question 3: If you apply a strong stimulus to the sensory receptor Your answer : c. action potentials will be generated at all 4 locations Stop & Think Questions: Observe the two neurons in the petri dish. What do you think is the resting membrane potential at the receiving end of the sensory neuron (sensory receptor) and the receiving end of the interneuron? You correctly answered: c. -70 mV Why is there no response at R3 when you apply a very weak stimulus to the sensory receptor? You correctly answered: c. The very weak stimulus does not depolarize the axon of the sensory neuron to threshold. Why is there a larger, depolarizing response at R1 when you apply a moderate intensity stimulus? You correctly answered: c. The stimulus induces a graded receptor potential at R1. Experiment Data: Stimulus

Sensory Neuron AP Frequency (Hz) in Axon

Sensory Neuron Vesicles Released from Axon Terminal

None Weak Moderate

Sensory Neuron Membrane Potential (mV) Receptor -70 -60 -40

0 16.6

Strong

-25

33.3

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Interneuron AP Frequency (Hz) in Axon

0 4

Interneuron Membrane Potential (mV) Receiving End -70 -70 -50

6

-40

10

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0 5

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Post-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1. What determines the amplitude of the depolarization at the sensory receptor (R1)? You correctly answered: a. The strength of the stimulus applied to the sensory receptor. 2. What determines the frequency of action potentials in the axon of the sensory neuron (R2)? You correctly answered: a. The amplitude of the depolarization at the sensory receptor (R1). 3. Which of the following directly determines the amount of neurotransmitter released at the axon terminal of the sensory neuron? You correctly answered: c. The amount of calcium that enters the sensory receptor. 4. Which of the following directly or indirectly determines the amount of neurotransmitter released at the axon terminal of the sensory neuron? You correctly answered: d. All of the above play a role in determining the amount of neurotransmitter released. 5. Which of the following directly or indirectly determines the frequency of action potentials in the axon of the interneuron? You correctly answered: d. All of the above play a role in determining the frequency of action potentials in the axon of the interneuron.

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Review Sheet Results 1. Why is the resting membrane potential the same value in both the sensory neuron and the interneuron? Your answer: because they have the same membrane potential. 2. Describe what happened when you applied a very weak stimulus to the sensory receptor. How well did the results compare with your prediction? Your answer: A small depolarization response will occur at R1, and action potential will occur at R2 and no responses will occrus at R3 and R4, the prediction was correct 3. Describe what happened when you applied a moderate stimulus was to the sensory receptor. How well did the results compare with your prediction? Your answer: the prediction was correct 4. Identify the type of membrane potential (graded receptor potential or action potential) that occurred at R1, R2, R3, and R4 when you applied a moderate stimulus (view Experiment Results to view the response to this stimulus). Your answer: R1-graded receptor potentil R2-Action potential R3-Action potential R4-Action potential 5. Describe what happened when you applied a strong stimulus to the sensory receptor. How well did the results compare with your prediction? Your answer: the prediction is correct

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