8.3 - How muscles work

what are 4 properties of muscles

• can be stimulated by nerve impulse

• shorten in length

• be stretched

• return to original length

what is sliding filament theory

when muscles contract, sarcomeres shorten, and actin + myosin slide over each other

what is the Z line

the middle of the protein discs, distance between two Z lines is the sarcomere

what is the A band

the length of myosin

what is the H zone

the middle of the A band that is lighter with only thick filaments

what is the I band

only thin filaments

how do muscles attach to bone

with tendons!

what are muscle pairs called and why are they needed

antagonistic pairs - muscles can only contract so pairs are needed for full range of motion

where are the bicep and triceps fixed to

bicep fixed to scapula and radius

triceps fixed to scapula, humerus, and ulna

what is the origin

the stationary bone the end of a muscle is fixed to

what is the attachment to the moveable bone called

insertion

what is the agonist

the muscle causing the desired action

what types of movement things are biceps and triceps

biceps are flexors, triceps are extensors

what are synergists

muscles that help the prime mover

may produce same movement or stabilize joint to prevent unwanted movement

what are fixators with examples

stabilize a part of body during movement of another part

stop wrist from flexing when fist is clenched

what is muscle tone

maintaining partial contraction of skeletal muscles

how does muscle tone work

many fibers take turns to contract so position can be held for a long period of time