BIOL 1107 Lecture Notes - Lecture 23: Cortisol, Leptin, Sympathetic Nervous System
Document Summary
Muscle fibers: (fast: slow ratio is hereditary) 1) slow twitch- oxidative (abs, back), slow sarcomeric contraction. 2) fast twitch- oxidative/ glycolytic (arms, legs), fast sarcomeric contraction. Stimulate glycolytic fast twitch, becomes oxidative, and you get stronger/ faster. Without constant stimulation, they will change back to glycolytic and you will slow down. On actin: myosin head can"t bind because a dimer is blocking the binding site. Add calcium ion to bind to dimer, to twist it away from the binding site, so now myosin head can bind. Cells remember how heavy something is, to use less atp next time= muscle. Cells start small until more is needed. 2) motor neurons with larger terminal end units. Membrane extends deep into muscle cell; action potential from nerve cell uses tube to go to sarcomere. Then calcium ions move into sarcomere and bind to proponin to pull away dimer. When action stops, calcium falls away and dimer twists back to original position.
