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Coordination in animals

Investigation of the nervous coordination process

Experiment 2.1

Investigating the knee-jerk reflex (patellar reflex)
FOR ONLINE READING ONLY
Aim: Demonstrating the knee-jerk reflex as an involuntary response controlled by
the spinal cord.
Materials
Reflex hammer (or rubber mallet), stool or chair, stopwatch (optional) and a volunteer
Procedure
1. Ask your fellow to sit on a high stool or bench with legs hanging freely as shown
in Figure 2.13.

Figure 2.13: Legs hanging freely
2. Locate the patellar tendon (just below the kneecap).
3. Tap the tendon gently but firmly with the reflex hammer.

4. Observe the response of the leg.
5. Repeat the test three times and measure the time of response using a stopwatch.
6. Tabulate your results as follows:

No. Reaction Time (s)
1.
2.
3.

Observation
(a) What did you observe? Give reason (s) for your answer.
(b) Write the observation of your experiment.
Questions

Describe path of message travel in this experiment.

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