Neurophysiology of Nerve Impulses Answer

Name: Exercise 3: Neurophysiology of Nerve Impulses: Activity 8: Chemical Synaptic Transmission and Neurotransmitter Release Lab Report Pre-lab Quiz Results You scored 80% by answering 4 out of 5 questions correctly. 1. The end of the axon where it contacts a target is called the You correctly answered: c. axon terminal. 2. Neurotransmitter is released into the synaptic gap by You correctly answered: a. exocytosis. 3. Exocytosis of neurotransmitter from the axon terminal is triggered by an increase in the intracellular concentration of You correctly answered: c. Ca2+ . 4. Neurotransmitter released into the synaptic gap reaches the target cell by Your answer : a. exocytosis. Correct answer: b. diffusion. 5. At the target, neurotransmitter You correctly answered: d. does all of the above. Experiment Results Predict Question: Predict Question 1: You have just observed that each action potential in a burst can trigger additional neurotransmitter release. If calcium ions are removed from the extracellular solution, what will happen to neurotransmitter release at the axon terminal? Your answer : c. There will be less neurotransmitter release. Predict Question 2: What will happen to neurotransmitter release when low amounts of calcium are added back to the extracellular solution? Your answer : b. Neurotransmitter release will increase a small amount. Predict Question 3: What will happen to neurotransmitter release when magnesium is added to the extracellular solution? Your answer : a. There will be no neurotransmitter release. Stop & Think Questions: Why does the stimulus intensity affect the amount of neurotransmitter release at the axon terminal? You correctly answered: d. Both a and b are correct. Why is there no neurotransmitter release from the axon terminal when there are no calcium ions in the extracellular solution? You correctly answered: c. Exocytosis of the synaptic vesicles is calcium dependent. Why did the high intensity stimulation fail to trigger the same amount of neurotransmitter release in the presence of extracellular Mg2+ as in the control extracellular solution? You correctly answered: a. Mg2+ blocks the calcium channels in the axon terminal. Experiment Data: Post-lab Quiz Results You scored 75% by answering 3 out of 4 questions correctly. 1. How is the neurotransmitter stored in the axon terminal before it is released? You correctly answered: c. contained in synaptic vessicles 2. Are neurotransmitter molecules released one at a time or in packets? You correctly answered: b. in packets 3. With the normal extracellular calcium concentration, [Ca2+ ], when the action potential reaches the axon terminal it triggers You correctly answered: b. release of neurotransmitter by exocytosis. 4. Comparing the low intensity stimulus to the high intensity stimulus, the high intensity stimulus causes Your answer: a. more neurotransmitter to be released from each synaptic vesicle Correct answer: b. more synaptic vesicles to undergo exocytosis Review Sheet Results 1. When the stimulus intensity is increased, what changes: the number of synaptic vesicles released or the amount of neurotransmitter per vesicle? Your answer: The number of synaptic vesicles released 2. What happened to the amount of neurotransmitter release when you switched from the control extracellular fluid to the extracellular fluid with no Ca2+ ? How well did the results compare with your prediction? Your answer: There was no neurotransmitter release. The prediction was not correct. 3. What happened to the amount of neurotransmitter release when you switched from the extracellular fluid with no Ca2+ to the extracellular fluid with low Ca2+ ? How well did the results compare with your prediction? Your answer: There was a little increase in neurotransmitter release. The prediction was correct 4. How did neurotransmitter release in the Mg2+ extracellular fluid compare to that in the control extracellular fluid? How well did the result compare with your prediction? Your answer: Mg2+ inhibits some of the neurotransmitter from being released. There was some neurotransmitter release. 5. How does Mg2+ block the effect of extracellular calcium on neurotransmitter release? Your answer: Mg2+ reduces the amount of synaptic vesivles that release neurotransmiter.