Unit 8 Reflection

In this unit, we talked a lot about the muscular system and how our muscles are classified. We also talked about muscle contraction, What Happens When You Stretch, and the various types of muscle twitch fibers.

The main themes we discussed were how the muscular system enables the movement of bones and fluids, maintains posture and body position, stabilizes the joints, and allows the body to generate heat. Muscles are generally named and classified by the direction of its fibers, size, shape, action, number of origins, and/or location of the muscle. We also talked a lot about the structure of muscles (shown in the diagram below). Each muscle fiber is an individual cell and has its own sarcoplasm and contains many microfibrils. These all make up sarcomeres.

We then went on to discuss how muscles contract (as shown in the diagram below) in what's known as the sliding filament theory. The main steps in muscle contractions are that the motor neurons send an impulse to the muscle that trigger acetylcholine to be released from vesicles. The acetylcholine binds to receptors that activate the second action potential. Then, calcium ions are released from the sarcoplasmic reticulum and into the cytoplasm. The calcium then binds to proteins that are wrapped around actin filaments. The binding of binding of the calcium ions causes myosin filaments to bid to and pull on the actin filaments, which causes the sarcomere to shorten, causing the muscle to contract. We also discussed the various muscle twitch fibers: slow twitch fibers, fast twitch A fibers, and fast twitch B fibers, and how each fiber is specialized for the type of exercise being done by that person. We also talked about how strenuous exercise can cause hypertrophy (when the muscle cells increase in size) and hyperplasia (when the muscle cells increase in number). We also discussed the difference between ligaments and tendons, the effects of muscle inactivity, and why our muscles get sore after exercise. In addition to these, we talked about the weight training basics like overload, progression, rest and recovery, and how the various muscle contractions are used in weight training.

Some unanswered questions I still have about the muscular system are: do muscles contract faster in people who work out more? where and how exactly does lactic acid fermentation occur in muscles?

In addition, we did a really cool Chicken Dissection to compare the anatomy of a chicken to our own anatomy, which furthered my understanding of the muscular system because it allowed me to visualize the different muscles and how they function. In addition, we did an activity on Creating a Better Joint which also helped me understand how various tendons, muscles, and blood vessels work together to keep a muscle from suffering any injuries. Throughout this unit, I've been pretty busy as we've had a lot of family visiting, so it's been hard to stay up to date with all the work. However, when it came time to study for the test, I remembered that the VARK questionnaire we did last semester told me that I learn better when I look at diagrams and draw/label pictures. Thus, I reviewed my chicken dissection and creating a better joint assignment in order to be able to visualize the various joints and muscles of the body.

I also looked back at my New Years Resolutions and realized that I've been meeting them a lot better now. I've been sleeping before 12 most days as I've realized that I do much better on tests and can concentrate much better in class when I sleep earlier rather than when I cram throughout the night. I've also noticed that I'm a lot more confident now that I was earlier in the semester. Now that all the college forms have been filled out, it's become more of a reality that I will be attending college next year. I'm so unbelievably excited to meet new people and learn new subjects that even my friends and family have noticed that I stand straighter and am overall much more willing to talk to people and reach out to people confidently.