BIO E121 Lecture Notes - Lecture 23: Motor Neuron, Delayed Onset Muscle Soreness, Troponin
Document Summary
Muscle contraction occurs as long as atp is present. Within 9 few hours after death, muscles become stiff = rigor mortis. Action & myosin gradually break down & muscles relax within 2-3 days. Motor unit: a motor neuron and all muscle cells it stimulates. All muscle cells in motor unit contract together. Muscles that have responsible precise movement have fewer muscle cells in each motor unit than do muscles responsible for less precise movements. 150 muscle cells in a motor unit. Single pulse of stimulation at or above threshold. Twitch: short single contraction due to single stimulation pulse. 2nd twitch builds on previous twitch from a delivery of a 2nd pulse after 1st pulse of stimulation. At threshold, increased stimulus frequency causes summation until tetanus is reached. Decline in muscle ability to maintain force after prolonged stimulation note normal contractions achieved by high frequency stimulation from motor neurons & alternating actions of motor units.
