Encounters #2

Relating what you learn in school, in this case Histology class, to what happens in your practical and everyday life can be interesting.

This past week, I decided to work out for a little bit, especially because I hadn't done any type of weight-bearing exercises in quite a few months. Although I do running and aerobic exercises at least twice a week, I did not do any weight-bearing, or muscle-building, exercises for months. Winter is just around the corner, and this desire to exercise will only weaken as I approach the colder months.

It was a coincidence that I decided to do these muscle-building exercises during the week that my professor had started the chapter on muscle tissue. It was perfect. When I continue with my exercises, I can now imagine what exactly is going on inside my body while I lift the dumbbell or do some push ups. I can now imagine the mechanism of the muscles working in my body while I, for example, do bicep curls with my dumbbell. I can now imagine what I am learning in class occur in my everyday life.

When I do bicep curls, the bicep muscle is contracting when I curl up and relaxing when I curl down. How do these muscles contract anyway? This mechanism is what I learned in my Histology class today.

(1)

Calcium is the most important element in muscle contraction. Muscle is composed of muscle fibers, also called myofibrils, are made up of myofilaments. There are two types of myofilaments: actin and myosin; also there is a protein critical for muscle contraction called troponin. These can be visualized on the diagram to your right.

Process of muscle contraction (2)

The process:
First, calcium is released, binding to troponin, which exposes the myosin-binding sites on the actin. Then, the myosin binds to actin, releasing ADP and forming a cross-bridge, causing the myosin to slide across the actin. ATP binds to myosin, causing it to let go of actin. Finally, when the calcium is returned, the muscle relaxes. All this occurs during one contraction.


Therefore, when I do those bicep curls, I will not only do it to be healthy and gain muscle so I can look like a strong man, but I will also imagine the beauty of what exactly goes on inside my muscle fibers during its contraction and relaxation.

Picture references:

(1) http://www.ucl.ac.uk/~sjjgsca/Muscleslidingfilament1.gif
(2) http://encyclopedia.lubopitko-bg.com/images/calcium%20and%20myosin%20in%20muscle%20contraction.jpg