FREE AND STUDY GAMES ABOUT PHYSIOEX EX3ACTVY5

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FREE AND STUDY GAMES ABOUT PHYSIOEX EX3ACTVY5

EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -13 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation

Question 1: Describe the phase of after-hyperpolarisation (or the undershoot)

Answer:

The flux through extra voltage K+ channels the depolarisation of the membrane to threshold & it also causes the membrane potential to become transiently more negative than the resting potential at the end of an action potential Question 2: What 3 things make it harder for the 2nd action potential to be generated after the 1st action potential?

Answer:

Voltage gated K+channels have opened, some voltage gated Na+ channels are inactivated & the efflux of K+ opposes a depolarisation towards threshold Question 3: Why is it harder to generate a second action potential during the relative refractory period?

Answer:

A greater stimulus is required because voltage-gated K+ channels that oppose depolarization are open during this time.

Question 4: What is the original threshold for this neuron?

Answer:

A 20 mV depolarization to -50 mV.

Question 5: What is the absolute refractory period?

Answer:

The interval at which the 2nd action potential falls. The time in which no action potential can be generated regardless of the strength of the stimulus.Question 6: If you further decrease the interval between the stimuli, will the threshold for the second action potential change?

Answer:

The threshold for the second action potential will be higher (requiring a larger depolarization).

Question 7: What is the refractory period?

Answer:

The time after an action potential where a 2nd action potential can be generated Question 8: Is the threshold for the 1st action potential the same or different from the 2nd action potential in a 60 msec interval?

Answer:

The threshold for the 1st action potential is lower than the threshold for the 2nd action potential

Question 9: What channels open during action potential? What do they do? Why?

Answer:

Voltage gatedK+ channels, more slowly. They contribute to the re-polarisation of the action potential from its peak as more potassium flows out of this second type of potassium channel Question 10: Judging from your results, what time period after the first action potential best describes the relative refractory period (the time when a second action potential can be generated only if the stimulus intensity is increased)?

Answer:

7.5 ms-60 msec

Question 11: As the interval between stimuli decreases, the depolarization needed to generate the second action potential

Answer:

increases.Question 12: At what interval between stimuli did the second action potential fail, regardless of the stimulus intensity? What is the absolute refractory period for this neuron?

Answer:

3.75 msec answer to both Q's Question 13: What happens 1-2 milliseconds after the voltage gated Na+ channels open?

Answer:

The channels inactivate meaning they no longer allow sodium to go through the channel. These channels cannot be re-opened by depolarisation for at least a few milliseconds so during this time fewer sodium channels can be opened.