functional groups of muscles

prime movers

provide the majority of the force needed for movements (usually the largest muscle operating at the joint)

antagonists

are usually located on the opposite side of the joint as the prime mover

(opposes the movement to make it slower and graceful)

synergists

works with the prime mover to make movements smoother by guiding movement

(helps stabilize joints)

fixators

holds joint bones in place, projecting against injury and making movements more efficient

myofibril

the tubes made of a bunch of sarcomeres that allows for contraction/relaxation of the muscle

sarcoplasmic reticulum

stores Ca2+ ions that are released into sarcoplasm when stimulated

t-tubules

conducts action potentials deep in muscle cell to signal the ST to release Ca2+

sarcolemma

cell membrane

how muscles contract

1st Ca2+ ions bind to a troponin which changes shape and causes tropomyosin to slide away from active sites of actin

2nd “cocked” myosin heads bind to actin active sites

3rd ADP and Pi are released from the myosin head and myosin head pulls the actin forward the M-line of the sarcomere in the “power stroke”

4th ATP binds to myosin head causing it to detach from actin

5th ATP is hydrolyzed (broken down) into ADP+ Pi and myosin head ”cocks” into postition to bind to actin site

troponin

holds tropomyosin in place over the actin active sites

tropomyosin

the band that covers the actin active site

sarcomere

is a single tube from the myofibril

m-line

the line where only the thick filament is

zone or overlap

i band

a band

z disc

secretory vesicle with acetylcholine(ACH)

axon terminal

voltage gated Ca2+ channel

synaptic cleft

cation (+)

stimulation

• action potential arrives at axon terminal signaling Ca2+ channels to open

• Ca2+ entry causes exocytosis to vesicles

• ACH is released into synaptic cleft

• ACH binds to ligand gated cation channels in motor end plate

• cations rush into muscle cell

• cations depolarizes the sarcolemma at motor end plate initiating action potential that spreads across sarcolemma

motor unit

a group of muscle fibers that are innervated and stimulated by the same motor neuron

muscle twitch

a muscle fibers response to a single neuronal action potential

EPOC

excess post exercise oxygen consumption (in lease in ventilation rate during and for a time after exercise)

muscle fatigue

inablility to maintain a certain lever of exercise wether that be for depletion of metabolites, decreased oxygen, accumulation of certain chemicals, or environmental conditions

latent period

an action potential spreads across the sarcolemma in a muscle twitch

contraction period

increasing smuggle tension due to corssbrige cycling in muscle twitching