KA 1.8- energy systems in muscle cells

What happens in muscle cells during vigorous exercise when there isnt enough oxygen?

• During vigorous exercise, the muscle cells do not get sufficent oxygen to support the electron transport chain.

• Under these conditions, puruvate is converted into to lactate

What is involved in the conversion of pyruvate to lactate?

• This conversion involves the transfer of hydrogen ions from the NADH produced during glycolysis, to pyruvate in order to produce lactate.

• This regenerates the NAD needed to maintain ATP production through glycolysis

What are the effects of lactate buildup in the muscles?

Lactate accumulates and muscle fatigue occurs

What happens when exercise stops and oxygen becomes available again?

• The oxygen debt is repaid when exercise is complete

• This allows respiration to provide the energy to convert lactate back to pyruvate and glucose in the liver

Describe slow-twitch muscle fibres ( contract, useful for, whats needed, major storage fuels)?

• slow twitch muscle fibers contract relatively slowly but can sustain contractions for longer

• They are useful for endurance activities such as long distance running, cycling and cross-country skiing

• They rely on aerobic respiartion to generate ATP and have many mitochondria, a large blood supply and a high concentration of the oxygen-storing protein myoglobin

• The major storage fuel of slow-twitch muscle fibres is fats

Describe fast-twitch muscle fibres ( contract, useful for, whats needed, major storage fuels)?

• Fast-twitch muscle fibres contract relatively quickly, over short periods

• They are useful for activities such as sprinting or weightlifting

• Fast-twitch muscle fibres can generate ATP through glycolysis only and have fewer mitochondria and a lower blood supply compared to slow-twitch muscle fibres

• The major storage fuel in fast twitch muscle fibres is glycogen