Types of Muscle Fibre Flashcards
What are features of slow-twitch muscle fibres ?
contract more slowly
less powerful contractions over a longer period of time
Deeply situated
Resistant to fatigue
Adapted to endurance work e.g marathon running
large store of myoglobin (bright red molecule that stores oxygen)
Small supply of glycogen- source of glucose for aerobic respiration
Rich supply of blood capillaries to supply glucose and oxygen to fibres
Numerous large mitochondria
Smaller store of calcium ions
slow rate of ATP hydrolysis in myosin heads.
What are features of fast-twitch muscle fibres ?
contract more rapidly
powerful contractions for a shorter period of time
Near the surface
quickly become fatigued-lactate accumulates rapidly
adapted to intense exercise e,g weight training
very little myoglobin- muscle appears a light colour
large glycogen, supply ATP largely obtained from glycolysis
Fewer blood capillaries
Fewer smaller mitochondria
Large store of calcium ions
High rate of ATP hydrolysis in myosin heads.
If an exam question asks how an individual’s muscles get bigger as a result of exercise, remember that it is the size of the fibres and not the number of fibres that increase!
