Energy Systems In Muscle Cells

Question 1

What happens during vigorous exercise?

Answer 1

Muscles do not get sufficient oxygen to support the electron transport chain, so pyruvate is converted into lactate instead of the following the normal pathway

Question 2

What happens to the hydrogens from the NADH produced in glycolysis?

Answer 2

They are transferred to pyruvate in order to produce lactate, regenerating the NAD needed to maintain ATP production during glycolysis

Question 3

What happens when lactate builds up in the muscles?

Answer 3

Muscle fatigue occurs and an oxygen debt is built up

Question 4

What happens when exercise stops?

Answer 4

The oxygen debt is repaid allowing respiration to provide the energy needed to convert lactate back to pyruvate and glucose in the liver

Question 5

Skeletal muscles are made up of what?

Answer 5

Fast and slow twitch muscle fibres.

Question 6

Explain slow twitch muscle fibres?

Answer 6

They are relatively slowly but can sustain the contractions for a long time relying on ATP from respiration

Have many mitochondria

Have a large supply

Have a high concentration of oxygen-storing protein called myoglobin.

Slow twitch muscle fibres are good for endurance activities such as long distance running or cycling.

The main storage fuel is fats

Question 7

Explain fast twitch muscle fibres?

Answer 7

Contract relatively quickly but only for a short period of time relying on ATP from glycolysis

Have fewer mitochondria

Have a lower blood supply

Are good for short bursts of activity such as weight lifting or sprinting

The main storage fuel is glycogen

Question 8

Information you need to know!

Answer 8

Most adults have a mixture of both types but athletes show distinct patterns of muscle fibres that reflect their sporting activity