When a muscle cell contracts, the intracellular calcium concentration decreases the myosin heads produce a single power stroke the position of each myosin head is identical at any give moment some myosin heads?

the endocrine system secretes hormones into blood and other body fluids. these chemicals are important for metabolism, growth, water and mineral balance, and the response to stress. hormones provide feedback to the brain to affect neural processing. reproductive hormones affect the development of the nervous system.

the transfer of energy between two molecules spaced just nanometers apart plays a key role in many technologies, including photovoltaics, quantum information systems, lighting, and sensors, as well as in biophysics to measure nanometer distances and in photosynthesis. but an open question in this area is what effect, if any, the surrounding photonic environment has on this nanoscale energy transfer. by designing and performing a carefully controlled experiment to answer this question, scientists have settled the debate and found clues to improving the efficiency of many of the technologies that rely on this process.

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