Types of Muscle fibers Flashcards
(19 cards)
What are the two criteria for classifying muscle fiber types?
The speed of contraction and how fibers produce ATP
What are the three main types of skeletal muscle fibers?
- Slow oxidative (SO) fibers
- Fast oxidative (FO) fibers
- Fast glycolytic (FG) fibers
How do slow oxidative (SO) fibers produce ATP?
Through aerobic respiration (oxygen and glucose)
What is a key characteristic of fast oxidative (FO) fibers?
They have fast contractions and primarily use aerobic respiration
Why can fast oxidative (FO) fibers fatigue more quickly than slow oxidative (SO) fibers?
Because they may switch to anaerobic respiration (glycolysis)
What is the primary ATP production method for fast glycolytic (FG) fibers?
Anaerobic glycolysis
What is the consequence of FG fibers primarily using anaerobic glycolysis?
They fatigue more quickly than SO and FO fibers
What determines the speed of muscle fiber contraction?
How quickly myosin’s ATPase hydrolyzes ATP
How much faster do fast fibers hydrolyze ATP compared to slow fibers?
Approximately twice as quickly
What is the difference in the metabolic pathways between oxidative and glycolytic fibers?
Oxidative fibers primarily produce ATP through aerobic pathways; glycolytic fibers primarily create ATP through anaerobic glycolysis
What advantage do oxidative fibers have over glycolytic fibers?
More ATP can be produced during each metabolic cycle, making them more resistant to fatigue
Why do oxidative fibers contain more mitochondria than glycolytic fibers?
Aerobic metabolism occurs in the mitochondria
What is a characteristic of slow oxidative (SO) fibers in terms of size and tension production?
They have a relatively small diameter and do not produce a large amount of tension
What is the role of myoglobin in slow oxidative (SO) fibers?
It stores some of the needed O2 within the fibers
What are the functional advantages of slow oxidative (SO) fibers?
- Useful in maintaining posture
- Producing isometric contractions
- Stabilizing bones and joints
- Making small movements
What type of movements are fast oxidative (FO) fibers primarily used for?
Movements like walking that require more energy than postural control but less than explosive movements
What is a distinguishing feature of fast glycolytic (FG) fibers regarding their appearance?
They have a white color due to low myoglobin content
What is the primary function of fast glycolytic (FG) fibers?
To produce rapid, forceful contractions for quick, powerful movements
What determines the predominant fiber type in a muscle?
The primary function of the muscle
