. IMG-2609.jpg v 1 Q Search 1. In Activity 1: Resting Membrane Potential, increa
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. IMG-2609.jpg v 1 Q Search 1. In Activity 1: Resting Membrane Potential, increasing the extracellular potassium (K) caused the o membrane potential to change to a less negative value. Briefly EXPLAIN WHY. The membrare po eniel Tess be cause tfve Cor, een rat 2 2. (circle one) Which stimulus modality induced a receptor potential, which led to an action potential in the Olfactory Receptor in Activity 2: Receptor Potential? a. pressure b. chemical c. heat d. light In Activity 3, you investigated Action Potentials and Threshold to reach an action potential. What change in membrane potentiak depolarizationor hyperpolarization) triggers an action potential? EXPLAIN WHY 3. gger an aerion. becaue pgeetive n mes hin an actton potental RSs 4. True of False: (circle one) During Activity 4, you investigated TTX and Lidocaine. Both of these chemicals blóck potassium (K) voltage gated channels from opening. 5. An action potential is an "all or nothing" event. Briefly explain what this means. As aution po al med or exceeded huh? k* vol Cha nn els frum ening (circle one) Conduction velocity is faster in a large diameter axon compared to a 6. True or False: small diameter axon. 7. In Activity 8: Chemical Synaptic Transmission and Neurotransmitter Release, you removed calcium ons from the extracellular fluid surrounding an axon terminal. How much neurotransmitter was sed? (circle one) none small amount EXPLAIN WHY large amount not neleas y hadExplanation / Answer
1. Usually the intracellular potassium is more than extracellular potassium. But increasing the extracellular potassium lowers the concentration gradient and reduces net potassium diffusion out of the cell. This leads to decrease in difference between the inside and outside the cell causing membrane potential to change to less negative value.
2. A chemical modality of moderate intensity will stimulate the olfactory receptor.
3. Depolarization results in less negative charge inside the cell. This shift from negative to positive charge inside the cell results in generation of an action potential. So we can say that depolarization is necessary to occur to generate action potential.
4. TTx and lidocaine are local anesthetics that block voltage gated sodium channels and thus prevent generation of action potential.
So the above statement is false.
5. Action potential is generated only when the depolarisation reaches the threshold of -55mV. If the threshold cannot be reached no action potential will be generated. This is known as all pr none principle.
6. True. Large diameter axons offer less resistance to ion flow and thus have higher conduction velocity than small axon.
7. Action potential causes change in voltage leading to voltage gated calcium channels to open. This causes extracellular calcium to move inside the neuron. Calcium ions bind to neurotransmitter containing vesicles and thus releasing the neurotransmitter. In absence of ECF calcium, none of neurotransmitter will be released.
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