Many of the symptoms you describe are vague and could be due to a number of things including Provera. Some of the common side effects of this medication include weight gain, weak bones, headaches, fatigue, swelling. These symptoms could also be caused by a number of things such as thyroid problems.
Myofibrils are assembled of repeated structures called sarcomeres â the smallest functional unit of muscle fiber. Each sarcomere is formed of actin (called thin) and myosin (called thick) filaments arranged in a precise order and of protein complexes which support the filament structures.
As we know myofibrils are the contractile units that make up each muscle fibre. Myofibrils can be looked upon as the building blocks of muscle and contain units called sarcomeres. Sarcomeres are the smallest functional unit of skeletal muscle and are composed of two protein filaments; actin and myosin. Actin is a thin filament and myosin is a thick filament, as shown on the following diagram, and it is the interaction between these two filaments that causes a muscle to contract and shorten.