producing movement - lesson 2

Question 1

what are the two attachment points for muscle on a bone?

Answer 1

origin and insertion

Question 2

what is the origin point?

Answer 2

attachment onto the bone that doesn’t move when the muscle contracts
- proximal end

Question 3

what is the insertion point?

Answer 3

attached to the bone that moves

- distal end

Question 4

how do muscles work to produce movement?

Answer 4

work in pairs - agonist + antagonist

Question 5

what is the agonist muscle?

Answer 5

prime mover

Question 6

what is the antagonist muscle?

Answer 6

muscle that relaxes

Question 7

what is reciprocal inhibition?

Answer 7

coordinated relaxing of muscles on one side of a joint to accommodate contraction on the other side of that joint

Question 8

what are the 3 types of contraction?

Answer 8

concentric contraction
eccentric contraction
isometric contraction

Question 9

describe concentric contraction

Answer 9

• muscle shortens

- movement in opposite direction to the gravitational pull

Question 10

describe eccentric contraction

Answer 10

• muscle lengthens
• movement with the direction of gravity
  (extension)

Question 11

describe isometric contraction

Answer 11

• 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

Question 12

what level does contraction occur at?

Answer 12

myofibrils

Question 13

what are the myofibrils?

Answer 13

• in muscle fiber

- contain numerous sarcomere which run parallel to the muscle belly

Question 14

what is the sarcomere?

Answer 14

• comprises the unit between the two Z lines and makes up the functional unit of a muscle fiber

Question 15

what is the structure of a sarcomere?

Answer 15

• Z lines
• actin
• myosin
• crossbridges
• H zone

Question 16

describe the z lines

Answer 16

• found at either end of the sarcomere

- come closer together in concentric contract and spread as the muscle relaxes

Question 17

describe actin

Answer 17

• 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

Question 18

describe myosin

Answer 18

• think protein filament which contains cross-bridges

- myosin cross-bridges attach to the actin when stimulated in the presence of calcium

Question 19

describe cross bridges

Answer 19

• 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)

Question 20

what are myosin and actin?

Answer 20

• contractile filaments which change the length of the sarcomere

Question 21

describe the H zone

Answer 21

• space between actin filaments which gets longer and shorter as the sarcomere changes length