-ATP site closely associated with actin binding site
-Position of the myosin
-release of ADP, so muscle can relax & new ATP can bind
Troponin- Tropomyosin complex
serve as a switch for muscle contraction and muscle relaxation
tropomyosin must be moved for myosin cross bridges to attach actin- requires ca++
Motor unit
a lower motor neuron & all of the skeletal muscle fibers stimulated by branches of its axon, larger units= more force, smaller units= finer degree of neural control
Muscle twitch
occurs when muscle is stimulated with a single electric shock, a quick contraction then relaxation
Latent period
time stimulus is applied until contraction begins
Contraction
beginning of contraction to peak
Relaxation
peak to end of contraction
All or none
a given response will be produced to its maximum extent in response to any stimulus equal to or greater than threshold response
ex- action potential to twitch
Temporal summation
asynchronous contraction, twitches alternate to produce a continuous maintenance of force
Spatial summation
recruitment, more cells = more force
Elastic components function
smooth out muscle behavior, absorbs some of the tension as a muscle contracts, elastic recoil help muscle return to resting length
slow twitch
small, rich in myoglobin (oxygen), sustain aerobic
fast twitch
larger, lots of thick & thin, low myoglobin (oxygen), less blood flow, fast to fatigue
Golgi tendon organs
can stop a muscle contraction, protective device, senses the tension muscle exerts on its tendons
Muscle spindles
senses muscle length, muscle that require the finest degree of control have the most
extrafusal: insert into tendons on each side
intrafusal: several thin muscle cells in connectrive tissue sheath
Final common pathway
motor pathway, consisting of the motor neurons by which nerve impulses from many central sources pass to a muscle
Smooth muscle cells
filaments in a spiraling pattern, no striations, can stretch greatly, big active range, gap junctions
single unit/ multiple unit
single: cells work as a collective group, lots of gap junctions
multiple: each cell functions independently, few gap junctions ex- eye
Buen Viaje lv.2 ch 8
