Unit 2 - Energy systems in muscle cells

Question 1

What do the muscles do during vigorous exercise?

Answer 1

Due to not enough oxygen being present to support the electron transport chain, pyruvate is converted in lactate instead of following normal pathway.

Question 2

What does NADH (produced from glycolysis) do?

Answer 2

NADH is transferred to pyruvate in order to produce lactate = regenerating NAD needed to maintain ATP production in glycolysis

Question 3

What happens when lactate builds up?

Answer 3

Muscle fatigue occurs and an oxygen debt is built up

Question 4

What happend when exercise stops?

Answer 4

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

Question 5

What are skeletal muscles made up of?

Answer 5

Skeletal muscles are made up of both fast and slow twitch muscle fibres

Question 6

How do slow twitch muscles function?

Answer 6

Slow twitch muscles contract slow but can sustain the contractions for a longer time relying on ATP from respiration

Question 7

How do fast twitch muscles function?

Answer 7

Fast twitch muscles contract quickly but only for a short time relying on ATP from glycolysis

Question 8

What are the features of slow twitch muscles?

Answer 8

• Many mitochondria
• Large blood supply
• High concentration of oxygen-storing protein (myoglobin)
• Good for endurance activites (Cycling, long distance running)
• Main storage fuel is fats

Question 9

What are the features of fast twitch muscles?

Answer 9

• Fewer mitochondria
• Lower blood supply
• Good for short bursts of activity (weight lifting, sprinting)
• Main storage fuel is glyocgen

Question 10

How do muscle fibres reflect our sport abilities?

Answer 10

• Most humans contain a mixture of slow/fast muscle fibres.

* Athletes show distinct patterns of muscle fibres that reflect their sporting activites