MCELLBI 32 Lecture Notes - Lecture 4: Motor Neuron, Active Transport, Skeletal Muscle

• School: Berkeley
• Department: Molecular And Cell Biology
• Course: MCELLBI 32
• Professor: Robin Ball

Document Summary

->motor unit: one motor neuron and all the fibers it innervates. ->skeletal muscle is made up of muscle fibers. ->motor neuron--neurotransmitter on muscle-->action potential in muscle-->release of ca from. Er-->increased cytosolic ca-->myosin-->myosin binds actin, forms crossbridges-->muscle contraction. ->after muscle contraction, ca goes backs into the er. Timing of action potential, ca rise, muscle contraction. ->muscle: short action potential (2 ms), ca remains a while in cytoplasm (100 ms), muscle force (2000 ms) ->except using hand, stimulating hand and then measuring with transducer (same thing as on leg in the last lab) ->in 2nd experiment, will change frequency of simulation. ->twitch duration is measuring the length of the hump ->measure time it gets from start to peak (contraction time) ->measure amplitude (how high the peak is (twitch tension)) Post-tetanic tension (optional: recruitment of more motor units with increasing stimulation. ->why? because all muscle fibers have recruited already: temporal summation (rate coding) ->incomplete tetanus-->relaxes a little but, goes to maximum--> fluctuates.