7.3 Twitch Fibres

Question 1

What are darker muscles in the legs called?

Answer 1

Fibres are called Slow Twitch Fibres.

Question 2

What are Slow Twitch Fibres specialised for?

Answer 2

Slower sustained contraction.

Able to cope with long periods of exercise.

Question 3

Due to the fact that Slow Twitch Fibres need to be able to cope with long periods of exercise, what do they need to carry out?

Answer 3

Need to carry out a large amount of aerobic respiration.

Question 4

What are the key features of Slow Twitch Fibres?

Answer 4

1. Many mitochondria.
2. High concentrations of respiratory enzymes which carry out aerobic respiration.
3. Large amounts of dark pigments myoglobin.