Physiology 206 Lecture 11 Outline of Last Lecture I Muscle II Thick filaments III Thin filaments IV Contraction V Types of contraction Outline of Current Lecture I Tetany II Motor neurons III Motor units IV Muscle fiber types V Muscle types Current Lecture 2 10 14 Tetany Muscle contracts and stays contracted Tetanic stimuli sensation that leads to tetany o 50 55 stimulations per second in human skeletal muscle o Electric current in US 60 stimulations per second Will deliver tetanic stimuli Accidental electrocution Reason why you can t let go muscles clench o Incandescent light flickers but we can t see it US adapted to 60 Rest of the world is 55 These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute Motor neurons fire tetanic stimuli to cause muscle contraction o How we can vary the length of contraction o Varying strength Caused by increasing or decreasing number of motor neurons firing contraction Motor Unit o One motor neuron and all of the muscles it innervates o Muscle cells are innervated by only 1 neuron o Small motor units allow for finer graded contractions Muscle Metabolism o In lack oxygen metabolites do not have enough substrates to metabolize all the way to carbon dioxide o Instead it only metabolized to lactic acid which is more acidic and causes pain are sustained use Muscle fiber types o Red muscle Slow fatigue Slow twitch doesn t contract as rapidly Myoglobin takes up more space Less space for actin and myosin Operates for much longer Has more myoglobin a red protein Related to hemoglobin Also binds to oxygen Carry around a reservoir of oxygen Allows for oxygen to be used even when oxygen intake is decreased o White muscle Fast fatigue Once enough oxygen cannot be gained to produce ATP lactic acid is made instead Fast twitch Smooth Muscle Actin and myosin are not arranged in parallel o Skeletal only shortens in the long direction o Smooth can shorten in every direction Cardiac Muscle Straited o o Actin and myosin are arranged in parallel like in skeletal HOWEVER they can send action potential to all neighboring cells like smooth muscle Have unstable resting potentials Atrial muscle o Only 1 action potential every 150 mmsec o Can contract twice as frequently as ventricular muscle Ventricular muscle o o Only 1 action potential every 300 mmsec Therefore only about 200 contractions per minute Conducting fibers
View Full Document
Unlocking...