A Woman Perpetually Falling

Cheryl is a woman who lost her sense of balance after she was prescribed too much gentamicin to treat an infection. Due to the overdose, her inner ear structures, including the vestibular apparatus, have been thoroughly damaged. The vestibular apparatus - a structure in the ear - is the organ tasked with helping a person sense space and orientation, and so, could no longer stand without falling. A neurologist by the name of Bach-y-Rita developed a helmet that could bypass the damages vestibular apparatus and send signals directly to the part of the brain that processes balance via the tongue. The longer Cheryl wore the helmet, the longer the effect lasted and Cheryl could stay balanced without the help of the device. Long term use also eventually makes permanent adjustments to the brain so that the residual effect last longer every time. This amazing ability of the brain to take over and redelegate  the jobs of damaged brain parts proves the plasticity of the brain.

"[Cheryl] suffers from mental fatigue, as well, from being on constant high alert. It takes a lot of brain power to maintain an upright position--brain power that is taken away from such mental functions as memory and the ability to calculate and reason" (5) All of our senses are interconnected - though Cheryl has lost her sense of balance, everything else in her life is affected too. She has trouble remembering, calculating, and reasoning, all abilities that were also compromised by the damage to her vestibular apparatus. Individual sense like  balance are not isolated in regions of the brain, so when one region is affect, other cognitive abilities are also impaired.

"Her residual effect progressed to multiple hours, to days, and then to four months. Now she does not use the device at all and longer considers herself a Wobbler" (10). This truly demonstrates the elasticity of the brain. The effects of using this device lasted even when Cheryl wasn't wearing the device because the brain was able to redelegate the cognitive abilities that were impaired to other parts of the brain.

"...my father had had a huge lesion from his stroke and that it had never healed, even though he recovered all those functions" (23). This was really interesting to read, because when my grandmother had a stoke, the part of the brain that died due to the stroke, never recovered. However, her speech, ability to use her left arm, and ability to walk all came back. Even though the damaged part of the brain didn't recover, other parts of the brain adapted and adopted the functions that the brian could no longer carry out. As a result, over a couple years of physical therapy and retraining of the brain, she regained her ability to speak, use her arm, and move.

Clay Brain

To further help us understand and visualize the brain, we made two models of the human brain out of clay. One model was of the left hemisphere along the sagittal plane, while the other one was of the right cerebral hemisphere. We googled images of the brain from various angles to ensure we knew exactly where the different parts were and then used different colors of Play-Doh to make each part. We then pieced the Play-Doh together to model the brain on a piece of card board.

Can Eating Healthier For Just One Month Really Make A Difference?

For those of you who don't know, 20 Time is an open-ended project, in which the teacher dedicates 20% of class time for students to work on this project. There are little to no restrictions as to what the topic can be, so it is a great opportunity for students to explore interests they've had outside of class but have never had the chance to pursue. For my 20 Time project, I want to analyze how changing my lifestyle for just one month can change my BMI, body fat percentage, heart rate, reading on an EKG, and/or weight. According to the CDC approximately 29.1 Americans - or roughly 9.3% of Americans - had diabetes in 2012, and the percentage has been rising every year. Because my family has a long history of diabetes and, as a teenager, I have a pretty unhealthy and carb-heavy diet, I have been told that I am almost pre-diabetic. My doctor has also warned me to start being careful with what I eat because skinny people can also be diabetic. So, it's about time I start eating a little bit healthier (like getting a salad for lunch instead of pasta and eating a granola bar instead of sugary cereal) and running regularly. One of my mom’s friends is a bariatric doctor - a doctor who specializes in the causes, preventions, and treatments of obesity - said she would be able to help me with finding a diet and doing the health tests. My plan is to have one control month where I continue eating how I’ve been eating and keep track of it like we did in the nutrition analysis last semester, and then do some tests at my mom’s friend’s bariatric clinic. In addition, I will record some things about my mood and concentration throughout the day. Then, the next month I will switch to healthier options for food that she suggests and run a mile each day after school. I will track my food consumption and runs, and then conduct the same health tests after this month. I will also record thoughts about my mood and concentration. Then, I will compare the tests to see how changing my diet and exercise habits for just one month will - or will not - help me be healthier and keep me from getting diabetes if the habits are continued in the long term. I’m hypothesizing that this project will show that exercise and healthier food can significantly reduce one’s chances of getting diabetes and just generally improve one’s health and mood. In todays world, according to the National Institute of Health, 35.7% of Americans are obese and about 74% of American men are obese. I think many people (and high school students especially) will be able to relate to my video and - if my hypothesis is supported - gain some insight into how they too can change their lifestyles just a little bit to help them live healthier lives.

The Woman With a Hole in her Brain

A 24 year old woman in the Shadong Province of China had a CAT scan done, which revealed that she had been born without a cerebellum. Although she learned to speak and walk much later than most people do and had some trouble with walking, she had managed to live a relatively healthy life to the age of 24. This goes to show how well the human brain can adapt and redistribute functions if need be. This is really interesting because many people who have a stroke cannot speak or eat properly; however, other parts of the brain (which are normally not in charge of speech or eating) can be taught to take over those functions adequately. Even when it comes to paralysis of limbs after a stroke, a different part of a stroke patient's brain can be trained to take over and carry out the motions of that limb. This also goes to show how amazingly versatile and flexible our brains are and how much there that we still don't know about them.

Your postcentral gyrus is another very important structure that is located in the parietal lobe of the brain. Because it is where the primary somatosensory cortex is located, it is responsible for one's sense of touch. Because the parietal lobe is in charge of language, sensory integration, and spatial reasoning, injuries to it can have a very broad range of consequences. People who have suffered severe injuries to their postcentral gyrus, for example, have poor spatial recognition skills and cannot speak or learn properly. If this part of the brain were completely missing, the person would be unable to sense touch as well, making it very difficult - if not impossible - to survive. 

Unit 5 Reflection

In Unit 5, we started off by talking a lot about the digestive system. Here's a sneak peak at what I knew prior to the unit, what I wanted to know, and what I've learned in terms of digestion:

The main functions of our digestive system include ingestion or good, secretion, propulsion of food through the body, digestion/breaking down of the food, absorption of nutrients from the food, and defecation or removal of feces. When food enters the body through the mouth, it is chewed up by the teeth in our mouth and saliva, forming a bolus (mass of broken down food) with the help of the hard palate - the roof of the mouth. This bolus then travels through the pharynx (throat) and to the esophagus, which uses peristalsis to move food into the stomach. The stomach is where physical change (the mashing of the food by the contraction of the stomach walls) and chemical change (the breakdown of food by gastric juices and acids) take place. The broken down food, now called chyme, then travels through the duodenum, jejunum, and ileum of the small intestine in that order. Accessory organs like the liver (which produces bile to break down large fats), the gallbladder (which stores the bile for the liver), and the pancreas (which produces enzymes) aid the small intestine. The small intestine is also lined with microvilli to increase absorption. Finally, the food enters the large intestine, where more absorption takes place, and then it is excreted through the anus as waste. This continuous flow of food through the digestive system is described in the diagram below, with all the main organs and their functions labelled. 

To better visualize the various organs that work together in our digestive system and how long the digestive system really is, we did a pretty interesting Digestive System Lab, which also allowed us to understand how it is the many intricate folds of the digestive system that allow it to fit in our abdomen. 

To build off of what we learned about the digestive system, we also discussed metabolism and the three states: fed state, fasting state, and starvation state. The three stages of energy extraction that the body goes through when food enters the body are large molecules get broken down into smaller monomers, those small molecules are then turned into Acetyl CoA, and the Krebs Cycle and Oxidative Phosphorylation are used in oxidation of the molecules to make ATP. The Fed State (absorptive state) occurs directly after a meal. During this state, sugars absorbed by the intestines travel directly to the liver and the pancreas releases insulin, which stops the release of glucagon. Excess amino acids are sent to the liver for processing and excess glucose and fatty acids are made into triglycerides and stored in the adipose tissue. The Fasting State (postabsorptive state) occurs within one hour of the meal and is when glycogen in the liver is converted to glucose and gluconeogenesis (the synthesis of glucose by the liver) occurs. The body begins to use fats for energy in order to conserve glucose (it is conserved for the brain and red blood cells). The liver also converts excess Acetyl CoA into ketone bodies. Lastly, during the Starvation State which occurs 4-5 days after fasting, the muscles start relying on adipose tissue for energy. The graph below depicts how the glucose and insulin levels in the body vary throughout the course of a normal day. Various organs like the brain, muscles, liver, adipose tissue, and heart, all also have specialized roles in our metabolism. Hormones like insulin, glucagon, adrenaline, and cortisol also coordinate with the body's metabolic processes to ensure that the body consistently has good nutrition. 

One of the main hormones that controls fuel metabolism is insulin. Insulin, a hormone produced by the beta cells of our pancreas, allows glucose to be taken up by liver cells and stimulates the synthesis of glycogen. It's like a "key" that unlocks cells by attaching to the "lock" (GLUT-4 receptors of the cell) and opening the door that allows glucose to enter the cell. In a normal cell, the main function of insulin as described above is shown in the diagram:

Now that we had discussed fuel metabolism and how it works in our bodies, we learned about disruptions that can occur, for example, diabetes - which occurs when the body cannot properly regulate the blood glucose levels. Essentially, the body has trouble regulating the insulin and glucagon in the blood, so the person's blood sugar levels get too high. Type 1 diabetes, an autoimmune disorder destroys pancreatic beta cells so that the body can no longer make insulin. In this type of diabetes, the GLUT-4 receptors stay trapped inside the cell and cannot go to the surface to allow glucose in (as it does in the picture above), so the glucose accumulates outside the cell, increasing the person's blood glucose levels. Type 2 diabetes, on the other hand, begins as insulin resistance. Because both types of diabetes can have extremely detrimental health effects, it is important to be aware of the symptoms (shown in the cartoon below) and be aware of your blood glucose levels, diet, and exercise to make sure you do not become diabetic. 

The endocrine system controls the processes involved in movement and physiological equilibrium, and includes all of the hormones, tissues, and glands. There are two types of hormones: steroid hormones and nonsteroid hormones. Steroid hormones are lipid soluble and diffuse through cell membranes, while nonsteroid hormones are not lipid soluble and are reveived by receptors external to the cell membrane. Both are regulated by negative feedback loops, by which the secretion of a specific hormone is turned on or off by physiological changes. Each of the glands in the endocrine system (depicted in the picture below) secretes specific hormones that are regulated in their own unique ways.

Lastly, we discussed the lymphatic system and how it functions in immunity by having immune cells on standby ready to respond to foreign cells, lipid absorption by having lacteals in the small intestine that absorb dietary lipids, and fluid recovery by absorbing plasma proteins and fluids from the tissues and returns it to the bloodstream. Lymph, a clear colorless, fluid flows through lymphatic capillaries, to lymphatic vessels, and to lymph nodes. Four mechanisms that enable lymph flow are rhythmic contractions, the skeletal muscle pump, a thoracic pump, and the rapid flow of blood in subclavian veins which draws lymph into it. Lymphocytes (B cells, T cells, and natural killer cells), which although are part of the lymphatic system, play a huge role in our immune system - see my Unit 4 Reflection for more information on the immune system. The lymph nodes, thymus, tonsils, and spleen also each play a key role in the lymphatic system.  

This unit went by pretty quickly and covered a lot of interesting topics. One thing that really helped me more fully understand the various topics were the articles we read. For example, "Stress, Metabolism, and Liquidating Your Assets" - a chapter from the book, Why Zebras Don't Get Ulcers - compared the digestive system to banks. The author discusses how surplus money is kept in mutual funds, tax-free bonds, etc. in much the same way that surplus energy is stored in triglycerides, glycogen and proteins. In addition, the article entitled "Does Your Metabolism Need an Overhaul?" discussed how even people with normal weight can be prediabetic. The article talks about how the speed and efficiency of metabolism depends on the amount of muscle a person has because muscles are the primary place where sugar is burned. Although it was a lot of material this unit, these additional readings provided analogies and alternative explanations that really helped me understand the material. Some unanswered questions I have are how the lymphatic system works together with the circulatory system to circulate lymph, how the lymphatic system works to fight against cancers, and what kinds of negative feedbacks help to regulate the endocrine system.

Reflecting on my Goals from the beginning of this semester, I'm happy to say that I've been improving a lot on my confidence. I've had a couple of college interviews in the past couple weeks, and made a point to have firm handshakes and catch myself if I started slouching during the interview. I also made sure to enunciate while talking (no mumbling), and ask a lot of well thought out questions. I think I'm getting a lot better at this goal and being critical of myself when I don't raise my hand in class enough or start to mumble when I'm talking to someone. 

I'm still working on my second goal - sleeping earlier - because it's hard not to procrastinate as a second semester senior. It's really good that I looked back at my goals, because now I know that is one I need to work on. I get home at 2:30pm every day and no longer have an endless list of college applications to work on, so there is no need for me to be sleeping so late. I generally have a biphasic sleeping cycle (where you nap once midday and then sleep for 5-6 hours), which had worked out brilliantly junior year and first semester of senior year because I had a lot of work and could generally concentrate better at night; however, this semester, I'm having trouble sleeping at night and do not have that much work, so there is no need for me to nap during the day. I'm really going to try harder to start and finish my homework as soon as I get home, so that I can get to bed by 11 as per my new year goals, and adopt a monophasic sleeping cycle.

School-wise, I can honestly say that the "second semester senior" feeling that everyone had been talking about has slowly but surely been kicking in. Nonetheless, I've been working on my studying habits a lot more, and can report that the VARK Questionnaire that I looked into in my Unit 4 Reflection from last semester has really helped me hone in on the studying strategies that work for me. From the VARK Questionnaire, I learned that visual aids, diagrams, and writing things down generally helps me study better. In AP Biology, we've been learning about DNA replication and Protein synthesis and in order to study for the test we had earlier this week, I hand-wrote my own notes as I read the textbook and consolidated my notes into diagrams where I drew out and labelled the DNA. In addition, in my AP Gov class, I've made sure to draw out flowcharts so I can keep a timeline of events in my head to make it easier to remember the material and the causes and effects of various events. I will also do this for the upcoming test in Anatomy, as drawing out the various body systems the way they are drawn out in the images in this post will really help me visualize how these systems work together to help our body maintain homeostasis.