Energetics of Contraction

摘要: Muscles convert energy from ATP into useful work, which can be used to move limbs and transport ions across membranes. The not converted work appears as heat. At the start of contraction heat is also produced when Ca(2+) binds troponin-C parvalbumin. use throughout an isometric at a rate that depends on duration stimulation, muscle type, temperature length. Between 30% 40% during fuels pumping Na(+) out myoplasm. When shortening, muscles produce less force than in but higher lengthening output splitting lower. Efficiency quantifies fraction provided by external work. Each molecule provides 100 zJ potentially mechanics myosin cross-bridge are such most 50 done one consuming cycle; is, maximum efficiency ∼50%. Cross-bridges tortoise approach this limit, producing over 90% possible per cycle. Other efficient contract more rapidly power.