Kinesiology 1080A/B Lecture Notes - Lecture 3: Muscle Contraction, Myocyte, Alpha Motor Neuron

• School: Western University
• Department: Kinesiology
• Course: Kinesiology 1080A/B
• Professor: Matthew Heath

Document Summary

Alpha-motorneurons = a neuron innervaing power-producing, extrafusal muscle iber. Motor unit = alpha-motorneuron and all the muscles it innervates, a unit of force producion in skeletal muscles. Faster conducion: the larger the iber diameter, the faster the conducion. # of muscle ibers associated with a motor unit ranges from 10 (eye) to thousands (back musculature) Intrafusal ibers oriented in parallel with extrafusal ibers. Detect stretch (lie perpendicular to alpha motor neurons: characterized by highest conducion velocity (100 m/s) Innervate fast twitch muscle ibers: characterized by medium conducion velocity (60 m/s) Innervate fast and/or slow twitch muscle ibers: characterized by slow conducion velocity (40 m/s) Three diferent shades of muscle ibers: dark red slow-twitch (more red blood cells, pale fast-twitch. Sprinter fast-twitch muscles, a lot of power over a short period of ime. Marathon runner slow-twitch muscle, moderate force over a long period of ime. Low force contracion, nearly all force produced by slowest motor units.