Unit 8 Reflection

 This unit was all about the muscles of the body and how they move, and the joints that connect them. There are many different movements that muscles perform, and there is an opposite reaction for every contraction. Antagonist muscles relax in order for agonists to flex. There are over 600 muscles in the body making it difficult to remember all of them, but by knowing the generic shape, size, action, origin and location, it is easy to make an educated guess. Muscle contraction starts at the axon terminal, which triggers an action potential. The vesicles release Ach into the cytoplasm which then bind to receptor sites. The shift in energy causes a second action potential, and allows the sarcoplasmic reticulum to open. As it opens, it is flooded with Ca2+ ions which attach to the troponin of the TT complex and changes its shape, which in turn pulls the tropomyosin in charge of protecting the myosin binding sites away. ATP energy then attaches to the myosin cross bridge and splits into ADP+P. As P flies off of the head, it causes it to shift forward. After ADP is pushed off, the head returns to its resting state.
Knowing this, muscle twitch fibers were easier to understand. There are three types of muscle fibers, slow twitch, and fast A and B twitch. These allows activities such as marathon running (slow), sprinting (fast A) and weight lifting (B).

We did several projects which helped us to see how these components worked. First we did a chicken lab, in which we dissected a supermarket chicken to examine its muscles, tendons and ligaments. We were able to compare many of the muscles to our human bodies. We also did a project in which we redesigned a joint to avoid common injuries that it may sustain. I chose the wrist joint because I have experienced a lot of injuries with it and wanted to see what could be improved.

Although this was a challenging unit, it was very interesting as well. the human body is a very complex system and the muscles are what allow us to move and function. It was helpful because I tied in this unit with the skeletal system unit which made learning about this much easier.