Excitation,_Contraction,_And_Relaxation_Of_Muscular_System

Excitation, Contraction, And Relaxation Of Muscular System Excitation, Contraction, and Relaxation of Muscular System Skeletal Muscle contraction requires a great deal of energy. Energy is required to break the bond between the myosin head and the actin active sites as well as for removal of calcium from the cytoplasm by the use of a special pump within the sarcoplasmic reticulum. When the myosin head is tilted forward, after the power stroke, a binding site for ATP (the chief energy currency of the cell) is exposed. The breakdown of ATP to ADP releases the head from the actin filament and cocks it for the next ratchet power stroke Energy is required for muscle contraction. At rest and during light exercise, muscles use lipids as their energy source. The use of carbohydrate becomes more important as the intensity of exercise increases. The breakdown of glucose to water and carbon dioxide generates energy that is transferred to regenerate phosphorylcreatine and ATP. When oxygen supplies are inadequate this process is short circuited and a metabolite (lactic acid) of one of the products builds up in the muscle. This is called anaerobic metabolism (glycolysis) and is a normal process that can occur prior to the oxidative breakdown of glucose. The lactate builds up in muscle, smooth, skeletal, action, energy, cell, cardiac, one, fiber, contraction, calcium, reticulum, potential, sarcoplasmic, after, within, visceral, process, present, potentials, myosin, exists, exercise, contractile, tissue, therefore, specialized, same, pump, oxygen, nerve, long, ions, heart, head, fibers