producing movement - lesson 2 Flashcards
what are the two attachment points for muscle on a bone?
origin and insertion
what is the origin point?
attachment onto the bone that doesn’t move when the muscle contracts
- proximal end
what is the insertion point?
attached to the bone that moves
- distal end
how do muscles work to produce movement?
work in pairs - agonist + antagonist
what is the agonist muscle?
prime mover
what is the antagonist muscle?
muscle that relaxes
what is reciprocal inhibition?
coordinated relaxing of muscles on one side of a joint to accommodate contraction on the other side of that joint
what are the 3 types of contraction?
concentric contraction
eccentric contraction
isometric contraction
describe concentric contraction
- muscle shortens
- movement in opposite direction to the gravitational pull
describe eccentric contraction
- muscle lengthens
- movement with the direction of gravity
(extension)
describe isometric contraction
- muscle doesn’t change in length
- contracts but doesn’t move
- greatest potential for force generation as the max number of cross-bridges can be attached to actin at the same time
what level does contraction occur at?
myofibrils
what are the myofibrils?
- in muscle fiber
- contain numerous sarcomere which run parallel to the muscle belly
what is the sarcomere?
- comprises the unit between the two Z lines and makes up the functional unit of a muscle fiber
what is the structure of a sarcomere?
- Z lines
- actin
- myosin
- crossbridges
- H zone
describe the z lines
- found at either end of the sarcomere
- come closer together in concentric contract and spread as the muscle relaxes
describe actin
- thin protein filaments attached to the z line
- cross bridges on the myosin attach to the actin when stimulated by the release of calcium to create movement
describe myosin
- think protein filament which contains cross-bridges
- myosin cross-bridges attach to the actin when stimulated in the presence of calcium
describe cross bridges
- tiny projections on myosin filaments that attach to the actin filaments
- pull actin towards the midline of sarcomere
- makes the H zone shorter = shortens sarcomere = shortens myofibril = movement (concentric)
what are myosin and actin?
- contractile filaments which change the length of the sarcomere
describe the H zone
- space between actin filaments which gets longer and shorter as the sarcomere changes length
