1.8 Flashcards
What happens during vigorious exercise?
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.
What happens when there is no oxygen present?
Hydrogen is picked up by NAD during the conversion of glucose to pyruvate in glycolysis. The hydrogen ions are then released to provide the hydrogen required to make lactate. NAD is regenerated to maintain ATP production during glycolysis. Lactate builds up in the muscles and causes muscle fatigue (due to too little ATP).
An oxygen debt builds up as there is not enough oxygen for respiration. When exercise stops, oxygen is breathed in again and the oxygen debt is repaid. Lactate is converted back into pyruvate and glucose in the liver and so aerobic respiration resumes.
What is type 1 of skeletal muscle fibres?
slow-twitch muscle fibres
What is type 2 of skeletal muscle fibres?
fast-twitch muscle fibres
What do skeletal muscles contain?
Skeletal muscles contain a genetically determined mixture of slow-twitch and fast-twitch fibres. In most muscles, a fairly even balance exists between the two but in some muscles, one type is in higher proportion than the other.
What is slow-twitch muscle fibres?
Slow twitch muscle fibres contract relatively slowly, but can sustain contractions for longer. They 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 fat.
What sports require more slow-twitch muscle fibres?
They are especially effective when put to use during endurance events such as rowing, cycling and long-distance running.
What is fast-twitch muscle fibres?
Fast-twitch muscle fibres depend on glycolysis to generate ATP 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.
What sports require more fast-twitch muscle fibres?
Fast-twitch muscle fibres contract relatively quickly, over short periods. They are useful for activities such as sprinting or weightlifting.
