Tuesday, May 10, 2016

Reflexes Lab Analysis



  1. Give a recap of what you did in this lab. Relate what you learned about neurons and reflexes in lecture to the applications in this lab. For example, what is a reflex, and how does it work?
In this lab, we tested different reflexes including the photopupillary reflex, knee jerk reflex, blink reflex, plantar reflex, and reaction time. Reflex actions are involuntary—they happen before you have time to think. When they happen, a nerve signal takes a shortcut through the spinal cord, rather than involving the brain. If we touch a very hot object, a sensory neuron sends a signal shooting from the hand to the spinal cord.

  1. Claims Evidence Reasoning: For each of the 5 parts, write a claim that explains what the specific reflex is.   Cite your evidence of it happening, or not, and then provide your reasoning for why that particular reflex occurred. If it didn’t, why?
In the photopupillary reflex part, a person covers his or her eyes with hands for an extended period of time and then is shined in the eye with a bright flashlight. The iris became a lot smaller, as the amount of light entering the eye triggered the reflex. The pupil contracts so that less light enters the eye.

In the knee jerk reflex/ patellar reflex portion, the spot just below my knee cap was hit with a small hammer, resulting in my leg immediately kicking out. This reflex, called a monosynaptic reflex, occurs because the knee tap causes the thigh muscle to stretch. This simultaneously sends out information to the spinal cord. When the quadriceps are fatigued, the patella reflex does not occur.

The blink reflex was tested when a clear sheet was held over my face and a cotton ball was thrown at it. Even though I understood that there was a barrier between the cotton ball and my face, I still blinked. This reflex occurred because humans instinctually will close their eyes if something is heading towards their eyes.

The plantar reflex was tested when a pen was dragged up the bottom of a foot. Naturally, the toes flexed and came closer together. This reflex occurred because the nerve system in developed humans is fully myelinated.

Lastly, we tested reaction time by dropping a ruler and measuring how far down it took for the person to close their hand and catch the ruler. I noticed that with each trial, the trial distances decreased as we got used to catching the ruler. However, when we texted, the first trial distance was more than twice the distance of the first regular trial distance. The first trial was 23 cm while the first trial with texting involved was 50 cm. However both trials decreased in distance for the next two trials.

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