Muscle Contractions

Question 1

Cross bridge formation

Answer 1

• a signal comes from the motor nerve activating the fibre
  -the heads of the myosin filaments temporarily attach themselves to the actin filaments

Question 2

Cross bridge movement

Answer 2

-similar to the stroking of the oars & movement or rowing shell
-movement of myosin filaments in relation to actin filaments
-shortening of the sacromere
=shortening of each sacromere is additive

Question 3

If sacromere are stretched further apart then optimal

Answer 3

Fewer cross bridges can form = less force produced

Question 4

If the sacromeres are too close together:

Answer 4

Gross bridges interfere with one another as they form = less force produced

Question 5

Sarcoplasmic reticulum:

Answer 5

= (net-like) labyrinth of tubules inside fibre

Question 6

T-tubules:

Answer 6

Connect sarcoplasmic reticulum with outer membrane (scarolemma)

Question 7

Connective tissue:

Answer 7

Comprised mainly of the protein collagen surrounds all myofivrils, muscle fibres & muscle fibre bundles
-part of the tendons that joint muscles to the bone

Question 8

Muscles:

Answer 8

Attached to the bones to create movement

Question 9

Tendons:

Answer 9

-the strong fibrous tissues that attach muscle to bone

Question 10

Motor nerves

Answer 10

Innervates many muscle fibres & is called a motor unit

Question 11

Acetylcholine

Answer 11

-allows impulses to cross gaps

Question 12

Muscle contraction:

Answer 12

Impulses arrive at neuro-muscular junction

Question 13

Impulses travel

Answer 13

-over sacrolemma, through t-tubules, calcium released from sacroplasmic reticulum

Question 14

Release of calcium

Answer 14

Causes molecular cross bridging of actin & myosin

Question 15

Type I fibres

Answer 15

-contract slowly
-contract for long time without fatigue
-produce less powerful contractions

Question 16

Type II fibres:

Answer 16

-contract quickly
-fatigue quickly
-produce more powerful contractions

Question 17

Slow twitch output

Answer 17

<20-25%
-lower power activities, endurance events

Question 18

Fast twitch peak:

Answer 18

-50 milliseconds
-500+ muscle fibres

Question 19

Slow twitch peak:

Answer 19

-100 milliseconds
-100 muscle fibres

Question 20

Non-athlete fibre

Answer 20

47-50% of each

Question 21

Distance athlete fibre:

Answer 21

70-80% slow twitch

Question 22

Sprinter fibres

Answer 22

30-35% slow twitch