muscle contraction at the organ level

isometric contraction

same length, changing tension

isotonic contraction

same tension, changing length

* includes concentric contraction and eccentric contraction

concentric contraction

muscle shortens and does work

eccentric contraction

muscle contracts as it lengthens

load

weight of the object being moved

motor unit

a motor neuron and all the muscle fibers it supplies

small motor units

innervate muscles that exhibit fine control like finger muscles

large motor units

innervate muscles that exhibit less precise movements like hip muscles

recruitment

increasing the strength of the stimulus by recruiting more motor units

* leads to an increasing force of contraction because more muscle fibers are stimulated

relative size of a the muscle

the bulkier the muscle, the more tension it can develop and the greater the strength

degree of muscle stretch

if the actin and myosin overlap too much or too little, the force of contraction decreases

load in the force of contraction

if you increase the load, you will increase the force of contraction

frequency of stimulus

if you increase the frequency of the stimulus, you will increase the force of contraction

3 methods that muscles get energy for contraction

* creatine phosphate
* anaerobic glycolysis and lactic acid
* aerobic respiration

creatine phosphate

can produce ATP quickly and produces 1 ATP at a time

anaerobic respiration and lactic acid

occurs within the cytoplasm of a cell and produces 2 ATP at a time

aerobic respiration

occurs within the mitochondria of a cell and requires oxygen to produce 32-34 ATP at a time