Reflexes Lab

In this lab, we learned about the various reflexes that we have in the body. As we know from learning about neurons, a reflex is the shorter pathway of certain reactions so that instead of firing signals all the way to the brain and back to the mentioned area, it first straight from a sensory neuron to the spinal cord, where it then bounces back to immediately signal mortar neurons to enact a certain response, oftentimes without us knowing it. Therefore, we sent out to find these reflexes and test them out for ourselves, with the photo pupillary, knee jerk, blink, and plantar reflexes, along with the general test of reaction time. All of these tests showed certain behaviors that occurred without our control, relating to the entire purpose of having reflexes which protect us by not sending signals all the way to the brain.

My eye in normal light

My eye once the flashlight was shown in my eye.

The first reflex we tested was the photopupillary reflex, which is supposed to make the pupil smaller in response to intense light. We tested this by closing both of my eyes and shining a flashlight into one, while the other while the other remained in the dark, and found that this reflex did happen(as seen from the photo evidence). This reflex worked because the sensory neurons detecting light(photoreceptors) only had to send a message up to the spinal cord, where it then bounced back to stimulate the ciliary body of the iris to contract in response.

The second reflex was the patellar, or knee jerk, reflex. Our knee is supposed to flinch or jerk outwards in response to a hard hit at the knee, and sure enough, after a test of this reflex, my knee did move without my intention. This reflex worked because the motor sensors in my knee were routed only to the spinal cord, after which the message to kick the leg was sent immediately through the motor neurons without my intention. Afterwards, we tested the reflex after doing 30 squats, and the reflex was less observed, due to the fatigue in  my muscles preventing the reflex from occurring super quickly.

The blink reflex was the next to come(in which we are supposed to blink in response to an oncoming object), and the test in this lab involving it included throwing a cotton ball at my eye with plastic wrap in front of my face. The sudden missile aimed at my face induced me to blink(uncontrolled by me whatsoever), showing that when unexpected things happen our reflexes really do help avoid disaster. Like all of the other reflexes, the blink reflex was induced by the quick timing of sensory neurons, the spinal cord, and motor neurons contracting the eye.

The plantar reflex, or the reflex in which your toes contract with the uncomfortable sensation of having a pen dragged up the sole of the foot, was unfortunately not observed in my test. A possible reason for why the reflex didn't occur in me could be that I was already thinking and anticipating the pen to go up my foot, so the surprise factor did not work as well as it should have.

Lastly, the reaction time test that we conducted was about dropping a ruler between my fingers and seeing how long it took for me to catch it. In the data table, below, you can see that my average reaction time was 0.28 seconds, which set the basis for the second test that we did.

This time, we would be testing the same thing but with the distraction of texting in our other hand, and, as expected, my reaction time was slower than it was before, and the average time was 0.33 seconds. This occurred most likely because the brain was so preoccupied with texting that it was unable to see the yardstick as quickly, and the sensory neurons in turn started the reflex to grab later than before.