Lab One: Leech Neurons

Introduction: For this lab, I have "dissected" a leech and isolated a neuron. From there, I tested reactions to different pressures, using an oscillator. Then the type of neuron was identified.

While it is very, very hard to see, this picture is when found the neuron using the manipulator with the oscillope trace. You can see a vertical "blip" on the screen in the upper left hand corner. That "blip" is the electric pulse which let me know I had located a cell.
From there, I injected it with a dye which would make it visible under an ultra-violet light. I then turned on the ultra-violet light and the neuron was visible.
Using different tools, such as a feather and foreceps, I poked the cell to see what kind of response it would invoke. I took that data, as well as the ultra-violet image, and determined it was a dyed "R" cell.

Here are my responses to the questions asked.


1. What is the electrode measuring?

The electrode is measuring the voltage inside of the cell; the transmembrane potential, also known as the membrane potential.

2. Why use leeches in neurophysiology experiments?

Leeches are used because they have a small number of neurons but those neurons are large in size. Also, no one seems to mind opening one up.

3. What is the difference between a sensory and a motor neuron?

Sensory neurons send information from ORGANS to the CENTRAL NERVOUS SYSTEM. They also have long dendrites and short axons. Motor neurons are the exact opposite. They send information from the CENTRAL NERVOUS SYSTEM to the organs. They also have short dendrites and long axons.

4. Do you think a leech experiences pain? What is pain?

~Yes, I do think leeches feel pain. They do have a brain, nerve cord, and ganglia. They clearly have neurons that transmit messages. Basically, they have all of the parts required to feel pain. They also have sensory organs on the head and body surface which enable them to detect light, temperature, and vibration.
~Pain is an uncomfortable feeling detected by sensory receptors sensitive to chemicals released by damaged tissues or excess stimuli of heat or pressure.

5. What were the two most interesting things about doing this lab?

The two most interesting things for myself were learning more about leeches (I knew next to nothing about them) and the membrane potential, including the voltage inside of cells.

6. Anything you found confusing or didn't like about the lab?

When identifying the cell, no explanation was offered for what the different types of cells meant. I just guessed it was what they reacted to determined which kind of cell they were.

Conclusion: After a hard day of opening up leeches, I think it is time to come to a close. I hope you learned as much as I did in this lab. It was interesting and humorous, with some of the graphics and clicking on things as they cut for you. Had I been attempting this personally, I doubt I would have gotten a neuron!