Completely lost on the activity questions from the book! Summer physiology is not my friend!
3.1
Explain why the resting membrane potential had the same value in the cell body and in the axon?
Describe what would happen to a resting membrane potential if the sodium potassium transport pump was blocked?
Describe what would happen to a resting membrane potential if the concentration of the concentration of large intracellular anions that are unable to cross the membrane is experimentally increased?
3.2
Are graded receptor potentials always depolarizing? Do graded receptor potentials always make it easier to induce action potentials?
Based on the definition of membrane depolarization in this activity, define membrane hyper polarization.
What do you think is the adequate stimulus for sensory receptors in the ear? Can you think of a stimulus that would inappropriately activate the sensory receptors in the ear if the stimulus had enough intensity?
3.3
Explain why the threshold voltage is not always the same value (between axons and within an axon)
Describe how the action potential is regenerated by the local ion flux at each location on the axon.
Why doesn’t the peak value of the action potential increase with stronger stimuli
3.4
If depolarizing membrane potentials open voltage-gated sodium channels, what closes them?
Why must a sushi chef go through years of training to prepare puffer fish for human consumption?
For action potential generation and propagation, are there any other cation channels that could substitute for the voltage-gated sodium channels if the sodium channels were blocked?
3.5
Explain how the absolute refractory period ensures directionality of action potential propagation.
Some tissues (for example, cardiac muscle) have long absolute refractory periods. Why would this be beneficial?
What do you think the benefit of a relative refractory period in an axon of a sensory neuron?
3.6
Compare the action potential frequency in a temperature sensitive sensory neuron exposed to warm water and then hot water.
When a long-duration stimulus is applied, what two determinates of an action potential refractory period are being overcome?
Suggest several ways to pharmacologically overcome a neuron’s refractory period and thereby increase the action potential frequency.
3.7
The squid utilizes a very large-diameter, unmyelinated axon to execute a rapid escape response when it perceives danger. How is this possible, given that the axon is unmyelinated?
When you burn your finger on a hot stove, you feel sharp, immediate pain, which later becomes slow, throbbing pain. These two types of pain are carried by different pain axons. Speculate on the axonal diameter and extent of myelination of these axons.
3.8
If you added more sodium to the extracellular solution, could the sodium substitute for the missing calcium?
How does botulinum toxin block synaptic transmission? Why is it used for cosmetic procedures
3.9
Why were the peak values of the action potentials at R2 and R4 the same when you applied a strong stimulus?
If the axons were unmyelinated, would the peak value of the action potential at R4 change relative to that at R2?
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