Nerve Impulses Lab Report

Name:shasou Exercise 3: Neurophysiology of Nerve Impulses: Activity 5: The Action Potential: Measuring Its Absolute and Relative Refractory Periods Lab Report Pre-lab Quiz Results You scored 50% by answering 2 out of 4 questions correctly. 1. Which of the following occurs after the peak of the action potential? Your answer : b. Voltage-gated K+ channels open. Correct answer: d. All of these occur. 2. What is meant by Na+ channel inactivation? Your answer : a. The Na+ channel opens when the membrane reaches threshold. Correct answer: b. The Na+ channel no longer allows Na+ ions to pass through it. 3. What happens when voltage-gated K+ channels open? You correctly answered: d. All of these occur. 4. It is harder to generate a second action potential
Your answer : b. The threshold for the second action potential will not change. Stop & Think Questions: Threshold can be defined as the minimum voltage needed to generate an action potential. Is the threshold for the first action potential the same as, or different from, the threshold for the second action potential with a 60 msec interval? You correctly answered: a. The threshold for the first action potential is lower than the threshold for the second action potential. Experiment Data: Interval Between Stimuli (msec) 250 125 60 60 60 30 30 30 30 15 7.5 3.75 Stimulus Voltage (mV) 20 20 20 25 30 30 35 40 45 60 60 60 Second Action Potential? Yes Yes No No Yes No No No Yes Yes Yes
Define inactivation as it applies to a voltage-gated sodium channel. Your answer: VOLTAGE-GADED SODIUM CHANNELS HAVE THREE TYPES OF STATES: DEACTIVATE, ACTIVATE AND INACTIVATE. CHANNELS IN THE DEACTIVATED STATE ARE THOUGHT TO BE BLOCKED. THE INACTIVATION IS REMOVED WHEN THE MEMBRANE POTENTIAL OF THE CELL REPOLARIZES... 2. Define the absolute refractory period. Your answer: ITS THE INTERVAL DURING WHICH A SECOND ACTION POTENTIAL CANNOT BE INITIATED, NO MATTER HOW BIG IS A STIMULUS IS APPLIED. 3. How did the threshold for the second action potential change as you further decreased the interval between the stimuli? How well did the results compare with your prediction? Your answer: MY PREDICTION WAS WRONG. THE TRESHOLD FOR THE SECOND POTENTIAL CHANGED. 4. Why is it harder to generate a second action potential during the relative refractory period? Your answer: SINCE THE NEURON IS HYPERPOLARIZED, LITTLE BIT MORE NEGATIVE THAN USUAL. ONLY STRONG SIGNALS CAN TRIGGER A SECOND ACTION POTENTIAL DURING THE RELATIVE REFRACTORY