Human Cells: Energy Systems in Muscle Cells Flashcards
During vigorous exercise, the muscle cells do not receive sufficient oxygen to support the electron transport chain. Under these conditions what happens?
Pyruvate is converted to lactate
The conversion of pyruvate to lactate involves what?
The transfer of hydrogen from the coenzyme NADH to pyruvate in order to produce lactate
This regenerates the NAD needed to maintain what?
ATP production through glycolysis
What occurs when lactate accumulates?
Muscle fatigue
When is the oxygen debt repaid?
When exercise is complete
What does the repaying of the oxygen debt allow?
Respiration to provide the energy required to convert lactate back to pyruvate and glucose in the liver
What do slow-twitch muscle fibres do and what are they useful for?
They contract relatively slowly, but can sustain contractions for longer.
They are useful for endurance activities such as long-distance running, cycling or cross-country skiing.
What are the features of slow-twitch muscle fibres?
They rely on aerobic respiration to generate ATP and have many mitochondria, a good supply and a high concentration of the oxygen-storing protein myoglobin
What is the major storage fuel of slow-twitch muscle fibres?
Fats
What do fast-twitch muscle fibres do?
Contract relatively quickly, over short periods
What are fast-twitch muscle fibres useful for?
Activities such as sprinting or weightlifting
How do fast-twitch muscle fibres generate ATP?
Through glycolysis only
What are the features of fast-twitch muscle fibres?
They have fewer mitochondria and a less good blood supply compared to slow-twitch muscle fibres
What is the major storage fuel of fast-twitch muscle fibres?
Glycogen
What does most human muscle tissue contain?
A mixture of both slow- and fast- twitch muscle fibres
