For the first half of this Unit we discussed the structure of the human heart (including the layers of the heart wall and the 4 chambers of the heart), the function of valves, the cardiac cycle, the circulatory system and its components, blood pressure, the different types of blood vessels, the different types of blood cells, and heart attacks. For a more detailed discussion of these topics, please click here to view my Mid-Unit Summary. The second half of this unit, we discussed how problems in the circulatory system (as we went over in the Heart Chalk Walk Activity) can lead to various cardiovascular diseases, specifically heart attacks and strokes. As I already detailed how heart attacks occur in my mid-unit summary, in this blog-post I will focus on strokes (shown in the picture below) and the respiratory system.
A stroke is a brain injury that occurs when the blood supply to part of the brain is interrupted by a blood clot (also known as an thrombus, if it's made in a blood vessel and stays there, or an embolus, if it forms in one part of the body and then travels to another). It is sometimes referred to as a "brain attack," as it is essentially the same as a heart attack, except that it occurs in the brain. There are two main types of strokes: ischemic strokes and hemorrhagic strokes. An ischemic stroke occurs when an artery that supplies blood to the brain is blocked - a condition often caused by atherosclerosis. The picture below shows how in an ischemic stroke, a blood clot (in this case, an embolus) formed in the heart during atrial fibrillation can travel through the aorta, common carotid artery, and internal carotid artery, settle in a branch of the internal carotid artery, and stop blood flow. A hemorrhagic stroke, on the other hand, occurs when an artery taking blood to the brain bursts, which can be caused by high blood pressure or excess cholesterol, and blood leaks out of the blood vessel and into the brain. The brain tissue that had its blood supply cut off by the stroke dies and other parts of the brain must be trained to take over the functions that the dead tissue was responsible for (also shown in the diagram below). A transient ischemic attack (or TIA) is a "warning stroke" that only lasts a couple minutes, but foreshadows that a larger stroke is probably in the near future. When someone is having a stroke, the signs to check if he or she is really having a stroke and to minimize the effects of the stroke are to check the acronym FAST - Face (ask the person to smile), Arms (ask the person to lift up both of their arms), Speech (ask the person a question and see if they can respond properly), and record the Time since their symptoms (this will make it much easier for doctors to determine the proper course of treatment). Often times, doctors use the tissue plasminogen activator (tPA) to bust the clot formed, stent insertion to open up the artery, or MERCI to retrieve the clot via a "corkscrew" method.
Cardiovascular health is extremely important in order for blood to consistently and properly flow throughout your body. Cardiovascular diseases like heart attacks and strokes hinder the flow of blood and are generally caused by atherosclerosis of the coronary arteries. Atherosclerosis is chronic inflammation caused by the excess consumption of sugars, polyunsaturated fats, or Omega-6, and it can severely damage the blood vessels. Other factors that can lead to cardiovascular disease are lack of exercise, being overweight, smoking, diabetes, metabolic syndromes, high blood pressure (caused by atherosclerosis), and high cholesterol. Thus, to promote cardiovascular health and reduce the chances of cardiovascular disease, one should try to control their blood pressure and cholesterol, stop smoking, eat a healthy diet, consume alcohol in moderation, control weight and diabetes, manage stress, and be aware of family genetic history. I still wonder about the role that genetic history plays in our cardiovascular health: if all of my grandparents and many of my uncles have had diabetes or cardiovascular diseases, what are the chances that I will get it too? In addition, how do the lungs of the respiratory system work with the circulatory system to oxygenate blood before returning it to the heart?
In addition, we discussed how the respiratory system works in conjunction with our circulatory system by oxygenating the blood that the circulatory system then pumps throughout the body. The main functions of the respiratory system are to deliver oxygen, remove carbon dioxide, filter the air we breath in, and regulate the pH of the blood. The respiratory involves many organs that work together. The nose (nasal cavity) is a large open chamber lined with mucus that contains the sinuses. The pharynx (throat) also lined with a mucous membrane is a passageway for food and air that sends air to the larynx and food to the esophagus. The tonsils, which are also located in the pharynx, trap bacteria from the air we breathe in. The larynx (voice box) is made of 9 cartilage rings, contains our vocal chords, and contains a flap called the epiglottis which directs food into the esophagus and keeps food out of the lungs. The trachea (wind pipe) is an organ made of cartilage and lined with a mucous membrane that is hard in the front and soft in the back to allow the esophagus to expand when a person swallows. The lungs (air sacs) are surrounded by a pleural membrane and contain a bronchiole tree and an alveolar sac, which is very thin and easily damaged but is responsible for gas exchange in the capillaries. The image below shows how these organs function together to help us breathe:
We also did a sheep heart dissection towards the end of this unit that helped us visualize the different parts of the heart by identifying them on a real heart. It made me realize that a diagram of the heart is a simplified representation of the heart. Many of the structures in the heart are much harder to identify in a real heart, but are generally in the same locations that diagrams show them in, which was pretty amazing to see. Click here to read my previous blog post about our Sheep Heart Dissection.
From this Unit, I realized how much of a visual learner I am. The various heart diagrams at the end of the heart dissection packet, diagrams like the ones I have inserted in my blog posts, and the sheep heart dissection all helped me visualize what we were learning much better - it made these cardiovascular diseases more relatable rather than just theoretical/textbook knowledge. I realized that these diseases are real and happening to people every single day, making the material more interesting to learn due to its relevancy. It also made me realize how much these diseases can affect me in the future, which is why I need to be more careful with my eating and exercise habits to ensure I don't get diabetes or cardiovascular diseases early in life. I also learned that I need to spend more time memorizing details that cannot be visualized, as it has always been hard for me to memorize facts. I think I'm definitely a better student after this unit, as I learned the importance of collaboration and working together, especially when it comes to labs like the dissection. In regards to the Unit 2 health goals, I think I'm doing much better with exercise as I have tennis practice everyday and have started running on the weekends. In addition, I've been more conscious of my eating and have been trying to consistently eat 3 meals a day. Lastly, I'm still pretty stressed out and sleep-deprived due to my class load and college applications, but am working on my time management so I can finish my work faster and sleep earlier. And if I find myself feeling too tired at the end of a day, I take a nap before starting my work. Though I still have a long way to go before my health is where I want it to be, I think I've made a lot of progress already and just need to work on it more.
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