Topic 6- Slow and fast twitch muscle fibres Flashcards
What are the two types of muscle fibres?
-Fast fibres
-Slow fibres
Do human muscles have both types of fibres?
-Yes
-Some muscles have higher proportions of a particular fibre type due to their different properties
What speed do fast muscle fibres contract?
-Rapidly
What amount of calcium ions do fast muscle fibres require?
-Large
-In order to stimulate contraction
What type of respiration do fast muscle fibres rely on?
-Anaerobic (for ATP supply)
What are fast mucle fibres suited to and why?
-short bursts of high-intensity activity
-as they fatigue quickly
-due to the lactate produced from anaerobic respiration
Give an example of where these fibres are usually found in high proportion
-limbs of animals that flee a predator or hunt prey at high speeds
-human eyelids
Explain why fast muscle fibres have fewer capillaries
-Blood containing glucose and oxygen flow through the capillaries
-This means they have quite a slow supply of oxygen and glucose for aerobic respiration
What are the low amounts of in fast muscle fibres? (makes them appear paler than slow)
-Myoglobin
-Myoglobin is a red pigment molecule that is similar to haemoglobin
-Myoglobin functions as a store of oxygen in muscles and increases the rate of oxygen absorption from the capillaries
What are slow twitch muscle fibres suited to?- why
-sustained activities like walking
-As they contract more slowly
-They fatigue less quickly due to less lactate production, making them ideal for endurance
What type of respiration do slow muscle fibres rely on?
-Aerobic
Give some examples of where there is a high proportion of slow muscle fibres
-limbs of animals that migrate or stalk prey over long distances
-Human back muscles
Why do slow mucle fibres have a denser capillary network?
-Blood containing glucose and oxygen flow through the capillaries
-This means they have a short diffusion distance and a good supply of oxygen and glucose for aerobic respiration
What is present in high levels in slow twitch muscles?
-High amounts of myoglobin, haemoglobin and mitochondria
-This increases the rate of oxygen supply, oxygen absorption and aerobic respiration
Describe the proportions of muscle fibres that different athletes will have
Athletes that train for short-burst, high-intensity:
-higher proportions of fast muscle fibres and lower proportions of slow muscle fibres in their arms and legs
Athletes that train for endurance activities:
- higher proportions of slow muscle fibres and lower proportions of fast muscle fibres in their arms and legs
-This may be biologically predispositioned but training can imporve this
What are the effects of training on muscles?
-It can influence which fibre types develop
-It can increase the number of capillaries and mitochondria present in muscles
