Reflexes and Reaction Rates

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Reflexes and Reaction Rates

Knee-jerk
1. Have the subject sit on a chair with legs crossed. The upper leg should be relaxed. 2. Locate the position of the kneecap on the upper leg and feel the large tendon below the midline of the kneecap. 3. Using a reflex hammer, gently strike the tendon below the kneecap. 4. Describe the movement of the leg.

5. Ask the subject to clench a book with both hands then strike the tendon again. Measure the distance of movement. Perform 10 trials. 6. Repeat the experiment for the other leg.
7. Compare the movement of the leg while the subject is relaxed with that when the subject is clenching the book. 8. Comment on any difference seen between the right and left legs.

|Trials |Left Leg (cm) |Right Leg (cm) |Left Leg (cm) |Right Leg (cm) | | | | |clenching book |clenching book | |1 | | | | | |2 | | | | | |3 | | | | | |4 | | | | | |5 | | | | | |6 | | | | | |7 | | | | | |8 | | | | | |9 | | | | | |10 | | | | | |Total | | | | | |Average | | | | | |Comparison between legs | | | |

Achilles Reflex
1. Remove the subject’s shoe. Have the subject kneel on a chair so that the feet hang over the edge of the chair. Relax the foot and then lightly tap the Achilles tendon with the reflex hammer. 2. Describe the movement of the foot.

|Description of Movement | |

Pupillary Response
1. Have the subject close one eye for approximately one minute. Ask the subject to open the closed eye and compare the size of the pupils. 2. Which pupil is larger?
3. Ask the subject to close both eyes for one minute. Have the subject open both eyes. Shine a penlight in one of the eyes. 4. Describe the changes you see in the pupils.

|Pupil size in room light |Pupil size Eyes closed 60s |Pupil size with pen light | | | | | |...
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