MUSCLE Flashcards
Description of the role of actin and myosin in muscle contraction
The sliding filament model describes the interaction of actin and myosin during muscle contraction. According to this model, neuronal impulses cause the release of calcium from the sarcoplasmic reticulum within muscle cells. The calcium then binds to troponin, a molecule that along with tropomyosin, blocks the binding sites for myosin on actin molecules. Calcium binding to troponin causes a shift in the troponin/tropomyosin complex, revealing the binding site for myosin. Myosin then binds to actin, causing a conformational change in myosin that “cocks” the head of the myosin molecule and slides the actin filament relative to myosin. ATP binds to myosin, causing it to detach from actin and “recharge” (rebend again). If another binding site is available on actin, myosin will bind again, and slide the actin filament even further.
Bone Growth
Long bones grow via endochondral ossification, which requires cartilaginous growth plates at the ends of long bones, that thicken as cartilage and later become ossified
