System Update: Anatomy & Physiology

The anatomy of skeletal muscle is very complex and comes together to reach a common goal; to effectively connect the bones and muscles to each other for body movement and support. Starting at the microscopic level there are thousands of muscle fibers which contain the sarcoplasmic reticulum that in essence stores calcium for muscle contraction. Inside the myofibrill inside the SR contains the sarcomere. The sarcomere is made up of two primary components – thin filaments containing two strands of actin and a single strand of regulatory protein: 2 thick filaments of myosin, held together by the Z disks and the M line. This all comes into play when one looks closer into the anatomical and physiological background of muscle contraction. The physiological makeup of muscle contraction is a complex process that happens at a microscopic level. It all begins at the nueromuscular junction where ACh is released by the synaptic terminal which then binds to receptors on the sarcolemma. A change in the charge in the sarcolemma causes for an action potential to spread across the entire surface of the myofibrill along the T-tubules. The Sarcoplasmic Reticulum releases Calcium ions making the calcium concentration in the SR higher. Next, the calcium ions bind to the troponin that is on the tropomyosin attached to the actin. A cross bridge is then formed when the head of the mysosin attaches to the active sights. As the cross bridge is binding, pivoting, and detaching muscle contraction occurs under the sliding filament theory. as this happens ATP is being broken down as energy.


 http://www.ncbi.nlm.nih.gov/books/NBK57140/
 http://muscle.ucsd.edu/musintro/struct.shtml
 http://ceaccp.oxfordjournals.org/content/6/1/1.full