PHSL-P 416 Lecture Notes - Lecture 21: Rigor Mortis, Myocyte, Axon
Document Summary
Rigor mortis: at death, channels are triggered, muscle contract & see movement, but then stays contracted. Calcium leaks out: result of binding: energy from myosin head is released. Sliding filament: resting phase, atp is already metabolized. Myosin head pivots back to resting phase: atp broken down to adp +p. Muscle fiber/muscle cell: nmj impacts at this level, numerous categories, fibers are continuum. Fiber type distribution determined mostly by genetics: motor unit: single motor neuron & all muscle fibers it innervates. Ratio innervation: number of muscle fibers per motor neuron: wide range- 5:1--1500:1. Functional impact: motor control vs. gross motor movement: more control with face/hands(5:1, more force with quadriceps (1500:1) Each receives same action potential so they all contract force output: smooth increases in force & smooth decreases in force. Limitations of recruitment: can only reach 75% of max volume contraction, cant get in between, starts at 5, used only with voluntary movement.
