Spinal Reflexes Flashcards
What is a reflex
Simple building blocks for movement
Give an example of a stretch reflex
Patellar tendon/knee jerk reflex
Where is the force transmitted in stretch reflex
Muscle fibres- more elastic than tendons, more stretch
What nerves are activated in stretch reflex
1a afferent sensory nerves
increases 1a afferents in dorsal horn
Overview of stretch reflex
Force transmitted to muscle fibres
Activates 1a afferent sensory nerves
Increases no. of APs in 1a afferents projecting through the dorsal horn into spinal cord
What are the 3 types of sensory afferent connections
- Contact of a-motoneurones- contraction of agonist muscle
- Reciprocal Inhibition
- Afferent firing up dorsal columns to thalamus & somatosensory cortex
What is a monosynaptic reflex
One synapse
No interneurones involved
What is reciprocal inhibition
Muscles use agonists and antagonists to move joints
Agonist contracts -> Antagonist relaxes
HOW- inhibitory interneurones decrease a-motoneurone to antagonist
What nerves are activated in inverse stretch reflex
1b afferent nerves from Golgi tendon organs (gto)
What is a Golgi tendon organ?
monitors muscle tension
What does inverse stretch reflex cause
inhibitory interneurones to agonist
Excitory interneurones to antagonist muscle
Info abt muscle tension to somatosensory cortex
What is the flexor/withdrawal reflexes
Uses info from pain receptors
Withdraw part of body affected by pain stimulus towards body
What does an increase in AP in nocireceptors cause
- Increase activity in flexor muscles of affected part
- Antagonist extensors inhibited
- To not fall, excitory interneurones excite contralateral extensors
- Inhibitory neurones inhibit contralateral flexors at same time
What is the fastest reflex
Stretch reflex
Can reflex be overriden consciously?
Yes
