Muscle Metabolism

Question 1

What are the features of a type I muscle fibre?

Answer 1

Low ATPase activity leading to a slow twitch

Oxidative metabolism

Question 2

What are the features of a type IIa muscle fibre?

Answer 2

High ATPase activity leading to fast twitch

Intermediate oxidative and glycolytic activity

Question 3

What are the features if a type IIb muscle fibre?

Answer 3

High ATPase activity leading to fast twitch

High glycolytic capacity

Question 4

Why are oxidative muscle fibres sometimes called red fibres?

Answer 4

They contain a large amount of myoglobin to increase the rate of oxygen diffusion and this makes them red in colour

Question 5

What are the features of a muscle fibre which uses predominantly glycolysis for its metabolism?

Answer 5

Large store fo glycogen
High concentrations of enzymes required for glycolysis
Contain little myoglobin
Surrounded by few blood vessels

Question 6

Which type of muscle fibre is resistant to fatigue?

Answer 6

Type I

Question 7

How is ATP generated in a muscle during the first few seconds of activity?

Answer 7

Phosphorylation of ADP by creatine phosphate

Question 8

What is the importance of creatine phosphate metabolism in muscles?

Answer 8

It allows time for the slower, multi enzyme processes of oxidative phosphorylation and glycolysis to initiate

Question 9

What substrates are used for oxidative metabolism during exercise?

Answer 9

Stored glycogen is used for the first 5-10 mins of exercise
Blood born glucose and fatty acids is used for the next 30mins
Beyond this point fatty acids become progressively more important for metabolism

Question 10

How many hours after exercise should metabolic stores be restored?

Answer 10

48 hours