an energy rich molecule found only in muscle fibers. it is three to six times more plentiful then atp in the sarcoplasm of a relaxed muscle fiber
anaerobic cellular respiration
is a series of atp producing reactions that do not require oxygen. glucose is catabolized to produce atp.
aerobic cellular respiration
a series of oxygen-requiring reactions that produce atp. this type of respiration produces enough atp for prolonged activity.
the inability of a muscle to maintain force of contraction after prolonged activity. It results mainly from changes within muscle fibers.
refers to added oxygen, over and above the resting oxygen consumption, that is taken into the body after exercise.
recovery oxygen uptake
a term for the elevated use of oxygen after exercise.
consists of a somatic motor neuron plus all the skeletal fibers it stimulates.
is the brief contraction of all the muscle fibers in a motor unit in response to a single action potential in its motor neuron
latent period phase 1
a brief delay occurs between application of the stimulus and the beginning of the contraction. during this period the action potential sweeps over the sarcolemma and calcium ions are released from the SR.
contraction period phase 2
during this time ca 2 binds to troponin, myosin-binding sites on actin are exposed and crossbridges form.
relaxation period (phase 3)
ca 2 is actively transported back to the sarcoplasmic reticulum, myosin binding sites are covered by tropomyosin, myosin heads detach from actin, tension in the muscle fiber decreases
when a muscle fiber receives enough stimulation to contract, it temporarily loses its excitability and cannot respond for a time.
motor unit recruitment
the process in which the number of active motor units increases. One factor for creating smooth movements instead of jerks. it delays muscle fatigue.
when a second stimulus occurs after the refractory period of the first stimulus is over, but before the skeletal muscle fiber has relaxed, the second contraction will actually be stronger than the first.
unfused (incomplete) tetanus
when a skeletal muscle fiber is stimulated at a rate of 20 to 30 times per second, it can only partially relax between stimuli. The result is a sustained but wavering contraction
fused complete tetanus
when a skeletal muscle fiber is stimulated at a higher rate it does not relax at all. The result is this, a sustained contraction in which individual twitches cannot be detected