Latte topic Flashcards
Lactic metabolism early
During vigorous exercise, the muscle cells do not get sufficient oxygen to support the electron transport chain.
Under these conditions, pyruvate is converted 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.
Lactate metabolism late
Lactate accumulates and muscle fatigue occurs.
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.
Pyruvate
Converted to lactate in absence of Oxygen
Slow twitch muscle fibres
Slow-twitch muscle fibres 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.
Slow-twitch muscle fibres rely on aerobic respiration 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.
Fast twitch muscle fibres
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 of fast-twitch muscle fibres is glycogen.
Human proportion of muscle fibres of slow and fast twitch
Most human muscle tissue contains a mixture of both slow- and fast-twitch muscle fibres. Athletes show distinct patterns of muscle fibres that reflect their sporting activities.
State the reason why muscle cells produce lactic acid during vigorous exercise.
No oxygen
