Reflexes Flashcards
Which neurons code velocity of stretch
1a afferents code velocity of stretch. They are very sensitive. They sense length and rate of CHANGE of the length. 1a muscle spindle sensory afferents convey fast, dynamic response. They sense VELOCITY.
Which neurons code velocity of stretch
1a afferents code velocity of stretch. They are very sensitive. They sense length and rate of change of the length. 1a muscle spindle sensory afferents convey fast, dynamic response.
Which muscle spindle afferents sense static length.
II afferents sense static length. They sense slow tonic response. So they code the duration of the stretch.
What do sensory afferents do when intrafusal fibers are stretched ?
Sensory afferents are activated and increase their action potential firing rate.
What happens if intrafusal fibers are unloaded = contraction
Afferents stop firing
Which muscle spindle afferents sense static length.
II afferents sense static length. They sense slow tonic response. So they code the DURATION of the stretch.
What happens if intrafusal fibers are unloaded = contraction
The sensory afferents stop firing during contraction of the intrafusal fibers because the intrafusal fibers are unloaded at that time.
When do the 1b afferents fire
1b afferents fire when the muscle connected to the GTO contract. They sense force and are protective.
Passive stretch
Stimulates muscle spindle more and GTO less
Contraction stimulates
GTO more and muscle spindle less
During Total Contraction
Only the GTO is firing the muscle spindle is totally silent. During passive stretch and contraction both are firing, but the muscle spindle fires more during passive stretch while the GTO fires more during contraction. However, during complete contraction the muscle spindle is completely silent and only the GTO fires.
