Unit One - Key Area 8

Question 1

What is the impact of exercise on muscle cells?

Answer 1

Muscle cells during vigorous exercise do not get sufficient oxygen to support the electron transport chain. Under these conditions, pyruvate is converted to lactate.

Question 2

Describe the production of lactate

Answer 2

When pyruvate is converted into lactate, this involves the transfer of hydrogen ions from the NADH produced in glycolysis to pyruvate in order to produce lactate.
This regenerates the NAD needed to maintain ATP production though glycolysis.

Question 3

Why does muscle fatigue occur?

Answer 3

because lactate accumulates

Question 4

What is the oxygen debt?

Answer 4

the amount of oxygen required after exercise to remove lactate and replace the cells oxygen reserves

Question 5

Describe slow-twitch muscle fibres?

Answer 5

contracts relatively slowly but can sustain contractions for longer, useful for endurance activities such as long distance running, cycling or cross country skiing, relies on aerobic respiration to generate ATP, have many mitochondria, a large blood supply and a high concentration of the oxygen storing protein myoglobin, and their major storage fuel is fats

Question 6

Describe fast-twitch muscle fibres?

Answer 6

contract relatively quickly, over short periods of time, useful for activities such as sprinting or weightlifting, can only generate ATP through glycolysis, have fewer mitochondria and a lower blood supply and their major storage fuel is glycogen

Question 7

Describe the patterns of muscle tissue in humans?

Answer 7

contain a mixture of slow-twitch and fast-twitch muscle fibres and athletes show distinct patters of muscle fibres which reflect their sporting activities