Leech Neuron Lab

Screen shot of Ultra-Violet Image of Neuron

Screen shot of Manipulator with Oscillope Trace

QUESTIONS ABOUT LEECH NEUROPHYSIOLOGY LAB:
(Answer these questions to get full exemplary lab credit (A-level, 18-20 points)

1. What is the electrode measuring? Electrodes measure the activity of the neurons, or the voltage of the cell. (Measurement of potential difference.) I found it very interesting that a neuron spike was only detected in the P cell that I found when a probe was used. This showed Action Potential.

2. Why use leeches in neurophysiology experiments? "The nervous system of the leech consists of the brain, the ventral nerve cord, and ganglia that are located in each segment along the nerve cord. The medicinal leech has 21 segmental ganglia, each containing 175 pairs of neurons. The relatively small number and the large size of the neurons have made leeches favorite subjects of neurobiologists." (From Leech Background Information on lab website.) So, a leech makes for a convenient subject because the neurons are large and can be located pretty easily.

3. What is the difference between a sensory and a motor neuron?
A sensory neuron transmits nerve impulses to the central nervous system after a sensory receptor has been stimulated. A motor nueron is a nerve cell that conducts nerve impulses away from the central nervous system and innervateds muscles and glands, called effectors.
4. Do you think a leech experiences pain? What is pain?

5. What were the two most interesting things about doing this lab?
1. The fact that a P cell reacts to a probe (medium) but not a forcep (high).
2. The dye injection allowing us to see the morphology of the neuron. Very cool!

6. Anything you found confusing or didn't like about the lab?
Not at all. I really enjoyed this one!