05.10.2016 Reflexes Lab

In this lab, we tested our different reflexes, such as our photopupillary reflex, our patellar reflex, our blink reflex, and our plantar reflex. Reflexes are involuntary reactions in response to a certain stimulus, such as light entering our eye or something hitting our knee. Rather than stimulus traveling all the way to the brain and the brain sending a response back, the stimulus only travels to the spinal cord. This decreases the response time so that the body can react faster and protect itself from danger.

The photopupillary reflex is when the pupil of the eye constricts due to too much light entering the eye. To test this reflex, we had one person cover her eyes for two minutes, then expose one eye to bright light and observe the change in pupil size. We found that the eye exposed to the bright light had a smaller pupil size than the eye protected from the bright light. This reflex evolved to protect too much light from entering the eye and blinding us, which would negatively affect our survival.

The patellar reflex, or the knee-jerk reflex, is when the leg kicks out when a certain area just below the knee is hit. To test this reflex, we had one person sit with her legs crossed so one leg can swing freely. When a certain place right below the kneecap is hit, that leg swung out due to the reflex. This reflex is to help us walk without having to think about it and also to help us regain our footing in case we stumble, which helps in running away from danger.

The blink reflex is what causes us to blink when something comes really close to our eyes. To test this reflex, we had one person hold a sheet of clear plastic wrap close to her face, then threw a crumpled-up paper towel at the plastic wrap. This caused the person to blink. This reflex protects things such as sand or bugs from entering and damaging our eyes, which are very important for survival.

The plantar reflex is when the foot curls in when the sole is stimulated. To test this reflex, we had one person use a capped pen to stroke the bare sole of the other person's foot from the heel to the big toe. This caused the person's toes to come closer and her foot to tense up. This reflex protects us when we accidentally step on something, causing us to quickly draw our foot away from the object so our foot, which is very important in moving around, does not become damaged.

We also tested our response time in catching a falling meterstick -- not a reflex, since our eyes must see meterstick fall, send a message to our brain, which then processes it and sends a message to our muscles to grab the meterstick. We tested our response time both when we were paying attention and when we were distracted by texting on our phones to see how "multitasking" affects our response time. I found that being distracted by texting increased my response time (made me slower). When I was not distracted, my response time was 0.19 seconds, but when I was distracted, my response time was 0.22 seconds. We collected data from all the students in the class and made a graph of average response times when being distracted versus when not being distracted.

being distracted by texting increased response times by about a tenth of a second