Skeletal Muscle II

Question 1

What does force generation depend on

Answer 1

1. Sarcomere length before contraction

2. Frequency of muscle action potentials

Question 2

What does maximum tension depend on

Answer 2

Start sarcomere length

Frequency of action potentials

Question 3

What does duration depend on

Answer 3

Ca2+ speed pumped into SR

Resistance to fatigue

Question 4

What does speed of contraction depend on

Answer 4

Myosin isoform

Question 5

Independent force generator

Answer 5

Myosin

Moves actin at a rate of 5-10 nm/atp

Question 6

Single twitches

Answer 6

Muscle relaxes completely between stimuli

Question 7

Summation

Answer 7

Stimuli closer together, do not allow the muscle to relax fully

Question 8

Unused tetanus

Answer 8

Stimuli are far enough apart to allow muscles to relax slightly between stimuli

Question 9

Complete tetanus

Answer 9

Muscle reaches steady tension. If muscle fatigues tension decrease rapidly

Question 10

Central fatigue

Answer 10

CNS- Psychological effects

-Protective Reflex

Question 11

Peripheral Fatigue

Answer 11

Neuromuscular junction- down in neurotransmitter, down in receptor activation
Excitation-Contraction coupling- change in muscle membrane potential
Ca2+ signal- SR Ca2+ leak, down in release or troponin interactions
Contraction-relaxation-depletion theories: PCr, ATP or Glycogen
Accumulation theories: H+, Pi, lactate

Question 12

Muscle fibre type 1

Answer 12

Slow twitch, oxidative fibres, red colour, packed mitochondria, fatigued resistant

Question 13

Fibre type IIa

Answer 13

Fast twitch, red colour

Question 14

Fibre type IIb

Answer 14

Fast twitch, glycolytic fibres, white colour, easily fatigued