The activities 3, 4 and 7 have been experimented. In inhibiting a Nerve Impulse, numerous physical factors and chemical agents can impair the ability of nerve fibers to function. In these activities they show this exactly. In these experiments, it showed the effects of various agents to nerve transmission. In testing the effects of ether, there will be a nerve that will be stimulated. The experiment is to see if ether has any permanent alteration in neural response of the nerve. I believe that it won’t because it has no lasting effect. Also, the experiments are to see if ether will have an effect on eliciting an action potential which I believe that it will make it difficult. Curare is a well known plant extract that South American Indians used to paralyze their pray. It blocks synaptic transmission by preventing the flow of neural impulses from neuron to neuron (Laboratory Manual). I believe that the effect of curare eliciting an action potential will lead to curare not being able to act on an action potential because it will block and slow down the stimulation from making any progress in the action potential. In experiment 7, which is testing the effects of Lidocaine, which is a sodium-channel antagonist that prevents sodium channels from opening, I believe that it will block the sodium channels from opening. And there will not be any effect on eliciting an action potential. In the experiment of Nerve Conduction Velocity, it is the change in the membrane potential on the outside of the nerve that is being observed. The change that occurs here during depolarization will be so minuscule that it must be amplified in order to be visible on the oscilloscope. In this experiment, we will determine and compare the conduction velocities of different types of nerves. We will examine four nerves: an earthworm nerve, a frog nerve, and two rat nerves. The earthworm is the smallest; the frog nerve is a medium-sized myelinated nerve, Rat nerve 1 is medium-sized unmyelinated nerve, and Rat 2 nerve is a large myelinated nerve which is the largest nerve in the group. We will observe the effects of size and myelination on nerve conductivity (Laboratory Manual). I believe that the rat nerve 2 will have the slowest conduction velocity because it is the largest nerve and the earthworm will have the fastest because it is the smallest nerve. Materials and Methods
Experiment 5 (Testing the Effects of Ether), Experiment 6 (Testing the Effects of Curare), Experiment 7 (Testing the Effects of Lidocaine) * Lidocaine
* Data collection unit
Experiment 5 (Effects of Ether)
1. Drag the bottle of Ether over to the nerve in between the stimulating electrodes and recording electrodes. Then dispense. 2. Set the Voltage to 1.0 and click single stimulus to stimulate the nerve. 3. Click on the Time (min) button on the oscilloscope. The screen will now display activity over the course of 10 minutes. Because of the change in the time scale, an action potential will look like a sharp vertical spike on the screen. 4. Increase the timer until it is set to 2.0 minutes. This sets the stimulus to stimulate the nerve every two minutes. Click stimulates to start the stimulations. Then watch the elapsed time display. With the change in the time scale, the action potential will look like a straight vertical line. 5. Click the stop button to stop this action and to return the elapsed time to 0.0. 6. Click the Time (msec) button on the oscilloscope to return it to its normal millisecond display. 7. Click clear to clear the oscilloscope for the next activity. 8. Clear the – button under interval between stimuli until it is reset to 0.00. Experiment 6 (Testing the Effects of Curare)
1. Drag the bottle of curare and position the dropper on the nerve in between the stimulating and recording electrodes. Release the mouse button to dispense...