Unit 8 Reflection

     This unit, we examined the muscular system focusing into the synovial joints, muscle classification, the way muscles work, major muscles, and muscle fibers. Our joints have various types of movements and connections that allow it to move in certain motions. Angular movements allow our limbs to flex away and towards our body. One example is Rotation, which occurs when a bone revolves around its own longitudinal axis. When we exercise, we utilize the various motions of angular joints, which in turn benefits our muscles since joints and muscles are closely related. Correctly using our joints is important because it is essential for proper joint and muscle health. We choreographed a synovial dance to better understand the movements, unfortunately I did not videotape our dance, but we used each of the terms during each of the movements to help us memorize and internalize the movements and their respective names. We also did a research project, where we re-designed a new joint that would better prevent injuries. If you want to see how I re-designed the ankle joint, click here! 

     We have three different types of muscles: skeletal, cardiac, and smooth. At the microscopic level, muscles contain excitability receiving and responding to various stimuli. For example, connective tissue holds muscle fibers together and fascia surrounds the entire muscle. There is consistent nerve and blood supply, which demands and uses a great deal of ATP. Muscles also work in opposition, where one muscle contracts while the other relaxes. For example, when the biceps brachii flexes, the triceps brachii relaxes. Each one of our muscles follows this contraction/relaxation rule. There are 40 superficial muscles divided into 12 regions on the anterior side and 27 superficial regions divided into 7 regions on the posterior side. They are organized by size, shape, action, number of origins, and location. Each one of those muscles plays a specific function for the body, for example: the gluteus maximus extends and rotates the thigh laterally and brings leg in line with the body. We took our understanding of muscles to a deeper level through the chicken dissection which helped us see the muscles in real life and see the opposition rule take place. The chicken's muscles allows us to compare them to the muscles in the human body. Click this link to see a detail recap of the lab: Chicken Dissection. 

Muscles have a very complex way of contracting involving very specific steps, here's the rundown:

1. Nerve sends impulse to the muscle fibers.
2. Ach activates the action potential on the muscle, and opens the sarcosplasmic reticulum.
3. Ca2+ ions are released from the sarcoplsmic reticulum and into the cytoplasm. 
4. The ions then bind onto the TT complex that is now exposed and wraps around the actin filaments. 
5.  ATP attaches onto the binding site at the myosin crossbridge. 
6. ATP split into ADP and P which causes the myosin head to move forward.
7. The P falls off and the myosin head attaches itself to the binding site on Actin.
8. ADP fals off and the myosin head retracts back to its resting position and pulls the actin forward simultaneously. 

This process is repeated until all of the calcium is removed from the TT complex, and this intricate cycle only describes one of the myosin fibers moving along the actin. There are bunches of these fibers per muscle, and we have around 650 muscles within the human body.  

Lastly, we examined muscles fibers and how they facilitate and respond to different types of exercise. We have 3 different muscle fibers: slow twitch fibers, fast twitch fibers a, and fast twitch fibers b. Slow twitch fibers are slow oxidative, meaning they are highly depend on a steady supply of oxygen and contains low storage of glycogen. These muscles are mostly seen in long distance athletes and exercise such as marathons. Fast twitch fibers a are fast oxidative, meaning it contracts fast and is moderately dependent on oxygen. They fatigue quickly and appear red/pink in color and are better suited for short distance exercise. Fast Twitch fibers b are fast glycolytic meaning they contain high levels of glycogen, yet a low oxidative capacity. Due to their lack in oxygen, they fatigue quickly and appear pink/white in color. These muscles are usually seen in athletes who participate in sprints or very short term exercises. 

I'm still curious about what kind of exercise generates hypertrophy/hyperplasia. I'm assuming cardio exercise would most likely initiate a growth in cells, while weightlifhting would cause a growth in muscle cell size. Still curious to how our muscles make that choice and the distinction. 

In these past few weeks, I have gained exponential progress for my 20 time, as I have collected 377 pads/tampons for homeless women! I got really proactive with asking people to donate and I'm really excited to donate them to Sacred Heart Community Service and see how these products will benefit the women who use the facility. I have become more productive with my study habits, as I have found a new method of writing down and defining all the terms on the study guide and going through the notes to make sure I truly understand everything has helped me understand the material more effectively.