Unit 7 Reflection

While the last unit dealt mostly with the foundation of our body structure, the skeletal system, this unit focuses on the structure, organization, and functions of its counterpart, the muscular system. I will begin reviewing from the smallest unit of muscles, the two protein filaments that make all of our movements possible: actin and myosin.

The picture above shows the mechanism for muscle contraction at a molecular level, with the myosin heads pictured in a variety of configurations and steps in the aptly named "power stroke" process, where the fibers slide parallel to each other in opposite directions. This contracts the unit of muscle, called a sarcomere, and long chains of these sarcomeres create a myofibril. While each sarcomere can only shorten a small amount, the myofibrils combine the effectiveness additively, allowing for the powerful, macroscale movements humans and other animals are capable of (see picture below). Now, the myofibrils are lined up side by side to create a highly effective muscle that is connected, at the ends, to tendons and thus to bones.

The process of contraction (called sliding filament theory) between the actin and myosin is best described with the video below.

In the human body there are a large number of muscles. They also, however, have slight relation to animals with similar body compositions, like chickens. In this lab, I go through a dissection of a chicken (because human cadavers are in short supply) and list and describe many of the major muscles.

        I have, recently, begun weight training- with the weight god Leon Ng- and have had extended periods of muscle soreness. I would like to know the causes of this, and whether it is true that people build muscle by causing little tears in the fibers to be rebuilt stronger.

         This unit was relatively challenging for me, as a student, because of the memorization heavy aspect of the muscles and naming of things like the tropomyosin protien or acetylcholine molecules. Thankfully, however, I was able to test the effectiveness of various studying techniques, for example, short and sweet reviewing every day, or diagram memorization. Now, I don't know how effective it is until I take the test itself, and thus I'm off.