Muscle fiber types and muscle receptors Flashcards
what are the 3 types of muscle fibres
Slow oxidative, fast oxidative, and fast glycolytic fibers
how are muscle fibres classified
according to contraction speed and primary mode of ATP production
what are the differences between fast and slow fibres
fast fibres
– Myosin with fast ATPase activity
– contracts faster
– relax more rapidly
slow fibres
– Myosin with slow ATPase activity
– Slow fiber contractions last approximately 10 times longer than fast fiber
compare the size of the fibre types
- Slow oxidative: Smallest size & force
- Fast oxidative: Intermediate size & force
- Fast glycolytic: Biggest size & force
what order are the fibre types recruited
- Slow oxidative fibers
- Fast oxidative fibers
- Fast glycolytic fibers
what is fatigue
Decline in a muscle’s ability to maintain a constant contraction force during repetitive stimulation.
what are causes of fatigue
Strong and sustained contractions
High intensity exercises: Build up of lactic acid.
Very high intensity: Depletion of acetylcholine
what are extrafusal fibres
contractile muscle fibers
Responsible for skeletal muscle contraction
what are extrafusal fibres innervated by
alpha motor neurons
what are intrafusal fibres
in the muscle spindle
Adjust sensitivity of muscle sensors to stretch
what are intrafusal fibres innervated by
gamma motor neurons
What are Ia sensoy fibres
annulospiral endings that wrap around the central portion of the spindle
what is the function of Ia sensory fibres
detection of muscle length and velocity
what are Type II sensory ending
flower-spray endings that are located around either end of spindle
what is the function of Type II sensory ending
detection of myscle length only
what is the function of the golgi tendon organ
Detect muscle tension
The increased tension in the tendon stretches Golgi tendon organs
what are the golgi tendon organs innervated by
type Ib afferents
α-motor neurons are responsible for _______
muscle contraction in extrafusal fibres
γ-motor neurons are responsible for _____
controlling intrafusal fibres to adjust/modulate the sensory activity in muscle spindles
