Muscles Antagonistic usually opposing muscle pairs ex biceptricep

Muscles

• Antagonistic- usually opposing muscle pairs ex bicep/tricep • Motor unit- all the muscle cells ( fibers) controlled by one neuron ( nerve) • Eye muscle very precise- 1 nerve to only a couple muscle cells • Leg muscle- 2000 muscle cells to a single nerve • Typical muscle will have many motor units

How much force? • Depends on: • 1) number of motor units activated – If 1 isn’t enough, more are “Recruited” • 2) amount of myosin heads activated by Ca++

Muscle tone • Some motor units are always activated in a muscle • Not enough to cause movement but enough to “firm” muscle

Atrophy • Muscle fibers not regularly stimulated will shrink ( lose actin/myosin) • Reversible at first but eventually cells die completely and are not replaced

2 mechanisms ( ways) to make ATP • Aerobic- plenty of Oxygen in muscle cells allows full breakdown of Glucose to water and Carbon Dioxide • Anaerobic or “Glycolysis”- not enough Oxygen, releases some energy but not full breakdown and leaves Lactic acid in muscle cells

Muscle fatigue • Muscle doesn’t respond even though nerve sends impulse • 2 causes: – Not enough Oxygen ( Lactic Acid buildup) – Not enough ATP ( shortage of Glucose)

Fast twitch/slow twitch • Fast twitch- pale, white meat, few mitochondria to produce energy – Ex: turkey breast- big burst of flight to get away from fox • Slow twitch- dark because of lots of myoglobin and mitochondria to produce energy slowly over a long time – Ex: turkey leg for all day standing or goose breast for all day flight • Humans- mixed so “pink”