Muscle 4

Question 1

central fatigue

Answer 1

feeling of tiredness and desire to cease activity

Question 2

peripheral fatigue

Answer 2

at neuromuscular junction; ACh synthesis can’t keep up with neuron during rate; muscle fails to reach threshold for firing AP

Question 3

peripheral fatigue at the t-tubule

Answer 3

repeated AP firing at the t-tubule causes a K+ build up, changing the threshold for APs in the muscle fibre (failed e-c coupling)

Question 4

peripheral fatigue within the muscle fibre

Answer 4

build up of inorganic phosphate, ADP, H+ and reduction of ATP

• reduced Ca2+ reuptake and release
• decreased Ca2+ sensitivity
• cross bridge cycle slowed

Question 5

velocity of shortening dependent on…

Answer 5

ability to hydrolyze ATP (differ with different iso forms of myosin heavy chain)

Question 6

slow fibres

Answer 6

contain myosin with slower ATPase activity (TYPE I)

Question 7

fast fibres

Answer 7

contain myosin with more rapid ATPase activity (TYPE II)

Question 8

skeletal muscle classification

Answer 8

• fast or slow

- oxidative or glycolytic

Question 9

oxidative fibres

Answer 9

contains large amounts of mitochondria and have high capacity for aerobic (oxidative) metabolism

Question 10

glycolytic fibres

Answer 10

contain few mitochondria but and abundance of glycolytic enzymes and a large storage of glycogen

Question 11

determinants of muscle force/tension developement

Answer 11

• fibre diameter
• fatiguability
• initial resting length
• frequency of activation
• number of muscle cells/units activated

Question 12

The amount of tension developed is directly proportional to…

Answer 12

number of cross bridges formed

Question 13

The force developed by a muscle fibre is increased by…

Answer 13

summation of multiple twitches

Question 14

twitch

Answer 14

a single AP in a single muscle fibre

Question 15

If a subsequent AP occurs before the muscle fibre relaxes, a more forceful contraction occurs due to…

Answer 15

summation of single twitches

Question 16

unfused tetanus

Answer 16

reaches steady state of contraction but stimuli are far enough apart that the muscle fibre slightly relaxes between stimuli

Question 17

fused tetanus

Answer 17

the stimulation rate is fast enough that the fibre does not relax, instead it reaches maximum tension and remains there

Question 18

One way to increase tension developed by a single muscle fibre is to increase….

Answer 18

rate at which AP occurs in fibre