Reflex Lab

Relate and Review:
In this lab, we tested all our different reflexes. We started with our photo pupillary reflex and tested this by covering our eye for an extended period of time and then revealing it to the light. When we did this the pupil expanded to allow more light to enter the eye. This reflex most likely evolved because early humans used to live in caves and when they had to go outside, they needed to be able to adjust from total darkness to light very quickly in order to be alert in case of danger. Next, we tested our patellar reflex by using a reflex hammer and lightly hitting the person under the knee. Their leg would immediately kick out when this was done correctly. This reflex most likely occurs to help people maintain their balance and catch themselves if they begin to fall. Then, we tested the same reflex, but after the person had done 30 air squats. When we did our experiment, we found that the reflex was more vigorous. We hypothesized that this was most likely because the squats simulated the body being off balance so the reaction was more intense. Next, we tested the plantar reflex by running a pen cap up the care bottom of a foot. When I did this, my partner's toes curled and got closer together. This was a normal response. Lastly, we did an experiment to test our response time. One person stood with their hand out and the other stood next to them and held the ruler above their hand. When the person was not expecting it, the person holding the ruler would drop it and the other person would catch it. Each distance correlated to specific time and we were able to calculate our average reaction time. Then, we did the same experiment, but this time, the person who was supposed to catch the ruler was texting. When we calculated the average time for this experiment, we found that the reaction time was significantly slower.
Claims, Evidence, Reasoning:
I. The reflex tested in part one was the photo pupillary reflex. This is the reflex that allows the pupil to increase or decrease in diameter depending on the amount of light entering the eye at the time. In our experiment, you see clear evidence that this reflex is functioning as we watched the pupil expand as the eye was revealed to light after time in the dark. We believed that this reflex was developed as a way of quickly adapting from dark to light or vice versa.
II. The reflex that we tested in this section of the lab was the patellar reflex. This is the reflex that causes your leg to kick when your knee is hit below the kneecap. My partner and I's patellar reflexes are working well as we both kicked our legs out when we were tapped. We believe that this reflex occurs as a way of keeping oneself balanced or to help us catch ourselves if we begin to fall.
III. The next reflex was the blink reflex. This is reflex is a result of our natural reaction to blink when something gets too close to our eyes. We saw that this reflex is very active as the person blinked almost immediately as the cotton ball was thrown. People have the blink reflex in order to protect their eyes from any debris or objects that get too close.
IV. In this section of the lab, we tested the plantar reflex. The plantar reflex is an important test to determine neurological health. When your toes flex and move close together, that is an indication of a healthy nervous system and is also the typical response for people. But, if your toes spread apart and point upward, that could be an indication of a more serious condition called Babinski's sign. In our experiment, my partner's reflex was perfectly normal as her toes flexed, moved close together, and pointed downward. This all occurred due to the healthy condition of the myelinated fibers.
V. The last reflex that we tested was our reaction time. This specific reflex measures how fast it takes the visual information to travel to your brain and then for your brain to send a motor command to the muscles in your arm and hand to grab the ruler. My experiment showed that every trial, my reflexes improved. However, when I did the same experiment while texting, the results were completely different. It took a much longer time for me to react while texting. This reveals how immense the danger of texting and driving can be. This specific reflex occurs as a prevention method. For example, when you are driving and the car in front of you suddenly breaks, you will break your car in response in order to avoid a car accident.
                                           

Brain Dissection

Questions

1. 

                                      

My personal drawing and picture of our brain, showing the cerebrum, cerebellum, and the brainstem. 

2. Cerebrum: Responsible for sensory and neural functions, also the initiation and coordination of voluntary actions

Cerebellum: Functions to coordinate and regulate the activity of the muscles

Brainstem: Consists of the medulla oblongata, pons, and midbrain. It continues downwards to form the spinal cord

3. The function of the myelin in a neuron is to act as a fatty covering on the dendrites of the neuron in order to speed up processing of the information. It occurs in places such as the eyes, where information needs to be processed quickly.

4. 

                                                 

A drawing of the cross-section and a photo. The pins in the brain represent the thalamus, optic nerve, medulla oblongata, pons, midbrain, corpus callosum, and hypothalamus. 

5. Thalamus (yellow pin): relays sensory info and acts as "center" for pain perception

Optic nerve (white pin): transmits impulse from the retina to the brain

Medulla oblongata (red pin): the lowest part of the brainstem, it contains the control center for the heart and lungs

Pons (blue pin): the area of the brainstem that connects the medulla oblongata and the thalamus

Midbrain (black pin): a part of the central nervous system that is associated with vision, hearing, and motor control

Corpus callosum (green): allows for communication between the two hemispheres of the brain

Hypothalamus (white pin): regulates the nervous system and connects it to the endocrine system via the pituitary gland

6.

                                       

A sketch and a photo to show the difference between white and gray matter. 

Relate and Review 

We started this lab my examining the outside of the brain. We located the meninges, the shiny covering on the outside of the brain. Next, we identified the cerebrum, cerebellum, and brainstem (as seen in pictures above). Then, we cut the brain in half longitudinally. From there we were able to locate the thalamus, optic nerve, medulla oblongata, pons, midbrain, corpus callosum, and the hypothalamus. Lastly, we made a cross sectional cut of the cerebrum and identified the gray matter and white matter. This related to what we have done so far as it helped to give us an actual visual of the parts of the brain we are learning about. It also helped us to see how all of the parts of the brain are connected and reinforced our understanding about each of the part's functions. 

Sheep Eye Dissection Analysis

In this lab, my partner and I dissected a sheep eye and were able to identify all internal and external structures of the eye. On the outside, we were able to identify the cornea, which appeared cloudy and is the first structure that light passes through. It is also the protective layer of the eye. We also identified the sclera, the very hard exterior of the eye, this is also the white of the eye. Next, we located the optic nerve, which is the second to last step in the path of light as it sends the information to the brain and the brain is able to process it into vision. Then we found the external eye muscle that allows our eye to move up, down, left, and right. Finally, we identified the fatty tissue. This was white and yellow in color and gives the eye cushioning.

For the second part of the lab, we cut into the eye to identify the interior anatomy of the eye. Cutting through the sclera was difficult, as it was quite tough. When we finally cut all around the eye, we identified the vitreous humor that resembled a jelly like substance. There is also the aqueous humor, which is located behind the cornea. Both the vitreous humor and aqueous humor help to maintain the shape of the eye. When we removed the retina, it revealed the choroid layer which was a thin black layer found in-between the sclera and the retina. In one place, the retina is firmly attached to the choroid. This part is known as the blind spot. Next, we removed the choroid which revealed the tapetum lucidum, that helps animals with their night vision as it functions to reflect light onto the retina.

Finally, we removed the vitreous humor and the lens to reveal the ciliary body. The ciliary body appears ridged. We then identified the lens. When the lens appears cloudy, that means it has a condition called a cataract. A cataract prevents or reduces the amount of light that reaches the retina. Then, we identified the pupil which is the opening in the center of the iris. Pupil size increases with decreased light intensity and decreases with increased light intensity. Lastly, we removed the cornea from the front of the eye and made small cuts in it. We noted that it was very thick, mostly likely to act as protection for the eye.

                                           

"A Women Perpetually Falling..."

This article was all about Cheryl Schiltz, a woman who feels like she is perpetually falling. She feels this way because of the vestibular apparatus, which is essentially the balance system, is no longer working. Following an incorrect dosage of gentamicin, Cheryl has lost her balance. "Now that her vestibular system is damaged, Cheryl has as much chance of regaining her balance as a person whose retina has been damaged". Despite all odds, Cheryl was able to regain her balance by using a device called an accelerometer to retrain her brain to balance. This device works by sending balance signals to her brain from her tongue. Eventually, the residual effect of the device could last for months at a time. I found the quote above very interesting because it shows just how small the chances were of recovery, but due to the brain's adaptability, Cheryl was able to make a full recovery. 

Later in the article, it talked about localization and how each of our senses has a receptor cell that specializes in detecting each of these senses. However, Paul Bach-y-Rita rejected these claims saying that "Our senses have an unexpectedly plastic nature, he discovered, and if one is damaged, another can sometimes take over for it, a process he calls 'sensory substitution'". This quote reminded me much of the "Women With a Hole in Her Brain" assignment. In that homework assignment, I learned that many parts of the brain can actually be absent and other parts of the brain will compensate. 

Another quote that I found especially interesting was "When Cheryl's brain developed a renewed vestibular sense... these changes were not the mysterious exception to the rule but the rule: the sensory cortex is plastic and adaptable". I believe this quote brought the article together nicely. It states that the rule is that the "sensory cortex is plastic and adaptable". I also believe that this quote also relates very nicely when talking about other parts of the body. Experiments talked about throughout this article have shown almost complete recovery from a man who suffered a life-threatening stroke and people who have been blind since birth that are now able to make out faces and see different shapes. 

Overall I found this article to be extremely interesting. The fact that the human body is so adaptable is amazing.

 

The Clay Brain

In this lab, we constructed the brain out of play-doh. We showed the brain from two different views, the left hemisphere along the sagittal plane, and the right cerebral hemisphere. This lab was a good way to interactively learn about the anatomy of the brain. It was also very helpful to see two different views of the brain. This was a little tricky at first, but after a while, we got the hang of it.

   

"The Women With a Hole in Her Brain"

I found this article extremely interesting. It is absolutely amazing that this woman was able to go about so much of her life normally when her entire cerebellum was missing. Despite the lack of the cerebellum, her brain was still able to fill that spot with cerebrospinal fluid in order to protect the brain against disease and act as a sort of cushion. There has never been a report of someone living through their adult life because people with the lack of a cerebellum die young and this missing part is only discovered in the autopsy. Since the cerebellum controls motor functions and the ability to speak, it is amazing that how even without it, this woman was still able to learn how to walk and talk. That just goes to show how adaptable the brain is.

Without the pons, the person would not be able to control their facial muscles, look from side to side, hear, and much more. Without all of those things, a person could still survive. However, sections of the lower pons help to control and stimulate the intensity of breathing while sections of the upper pons decrease depth and frequency of breaths. A person would not be able to survive without their pons. If there was damage to the pons, the person may find an effect on their sleeping patterns and habits as the pons has control of the sleep cycle.

Unit 5 Reflection

The first thing that we learned about in this unit was the digestive system. The digestive system all begins in the mouth, where the food you chew forms a bolus. The bolus then moves to the pharynx, which is the passageway from the mouth to the esophagus. When the bolus reaches the esophagus, peristalsis moves the food into the stomach. Once the food has entered the stomach, the food is "mashed up" and covered with digestive enzymes. When the food leaves the stomach, it is then called chyme. From the stomach, chyme travels to the small intestine where absorption of the nutrients and digestion takes place. Your pancreas is located in the small intestine and is imperative for digestion as it produces many of the digestive enzymes, such as lactase which works to digest lactose. The small intestine is also lined with microvilli in order to increase absorption. The food is then moved to the large intestine, which extends from the ileocecal valve all the way to the anus. In the large intestine, the indigestible food is dried out and water is absorbed. Your large intestine also secretes large amounts of mucous in order to lubricate the sides of the intestine. During this unit, youwe did a lab that measured the length of our digestive tract. It is amazing to think that your digestive tract stretched out could be taller than you. Digestive System Lab

The next thing that we discussed was all about metabolism. We learned that there are three states. The first is the fed state. In the fed state, the sugars are absorbed by the intestine and travel directly to the liver while the pancreas releases insulin. In addition, the majority of glucose taken in by the liver is converted to glycogen. Next is the fasting state. In the fasting state, all glucose is used by cells so the body must continue to make glucose available in order to maintain blood glucose levels. During this state, your insulin levels drop while glucagon levels rise. Gluconeogenesis also occurs and the liver synthesizes glucose from amino acids and glycerol. Your liver then converts fatty acids in ketone bodies. Ketone bodies happen when carbs are low and fatty acids need to be broken down for energy. The next state is the starvation state. During the starvation state, your muscles rely solely on adipose tissue for fuel. The brain also switches ketone bodies for fuel in order to conserve protein. How long you survive during this state is dependent on how much fat you have stored. We then talked about organ specialization and how the liver is the "master of the metabolism". The liver's main job is to maintain proper blood glucose levels. We then discussed the major hormones, insulin, glucagon, cortisol, noradrenaline/adrenaline. Insulin will signal high glucose levels while glucagon will signal low glucose level. In conclusion, metabolism essentially depends upon your genetic makeup, the enzymes you produce, hormones, and if you have a good nutritional balance and live a healthy life. In the article "Does Your Metabolism Need an Overhaul" I learned that building muscle is an essential part of maintaining a healthy metabolism as well as preventing diabetes. I found that article very interesting and it definitely got me to do much more than cardio when I am working out.

The next thing we spoke about was diabetes, as it is a disruption in your fuel metabolism. An important hormone when talking about diabetes is insulin. Insulin is the "key" that "unlocks" cells allowing glucose to enter. When a person is diagnosed with type 1 diabetes, that means that your body is experiencing an auto-immune disorder. In this case, your body does not make insulin all and you are considered "insulin-dependent". For type 1 diabetes, you must take insulin shots daily. Type 2 diabetes is more common than type 1 as is occurs mostly in adults. Type 2 diabetes is a resistance to insulin as the body does not respond to insulin properly. In order to manage diabetes, people must try to keep their blood glucose levels as close to normal as possible. In addition, a proper diet and exercise are essential.

Next, we talked all about the Endocrine System. The endocrine system controls the processes involved in movement and physiological equilibrium and hormones are critical for this. One important hormone are steroid hormones. Steroid hormones pass through the cell membrane and then bind to specific receptors. They then enter the nucleus and bind to the cells DNA which then activates certain genes. From there, mRNA is synthesized in the nucleus and enters the cytoplasm and promotes protein synthesis for things such as tissue growth and repair and regulation of enzyme function. Homeostasis is maintained in the endocrine system by negative feedback, secretion of a specific hormone is turned on or off by a specific physiological change.

The last thing that we talked about was the lymphatic system. The major functions of the lymphatic system are immunity, lipid absorption, and fluid recovery. Lymph is the fluid that flows within the lymphatic vessels. Lymphatic tissue is specialized connective tissue that contains lymphocytes. Lymph capillaries are located everywhere in the body, except bone marrow, cornea, and the cartilage. Another major part of the lymphatic system in lymph nodes which help to filter lymph by trapping foreign substances and then are destroyed by immune cells.

Since I came up with my new year goals, I believe that I have been following them pretty well. Now that we are into February, I want to continue the momentum that I have going. A lot of times, as the year goes on I tend to lose motivation so I hope to continue the motivation that I have right now.