NAS L10 Flashcards
What are the general functions of reflexes?
- Protective e.g. limb withdrawal, cough reflex, skeletal muscle damage
- postural control e.g. walking
- homeostasis e.g. blood pressure
What are clinically relevant reflexes?
Deep tendon reflexes and pupillary reflex - autonomic as smooth muscle
What are the neural components of reflexes?
Sensory receptor –>afferent –>integration–>efferent –>effector.
Or can have no integration and go straight from afferent to efferent
What neurons are involved in integration of info? What do they do?
interneurons
Modulate input and ouputs. Tell the brain why you did a reflex even though the reflex happens first.
What’s an example of a simple stretch reflex?
Myotatic. Posture - adjust degree of skeletal muscle contraction. Sensory receptors are proprioceptors.
Example of a stretch reflex used clinically
Knee jerk reaction
What afferents do muscle spindles and GTOs use?
Ia muscle spindle
Ib GTO
Why are GTO uses in proprioception
postural control; gives muscle tension info
How many synapses in muscle spindle stretch reflex?
monosynaptic
Describe GTO
Uses Ib afferents. Gives muscle tension info. Polysynaptic, has Ib interneurons that are inhibitory in the ventral horn. Some Ib inhibitory interneurons synapse with same muscle. Reflex arc protects the muscle from being overloaded. Normal function tho is to keep tension in optimal range especially fine motor control e.g. fragile obkects in hands.
Not all reflexes use proprioceptors as their sensory receptors. Give an example.
Withdrawal reflex e.g. pain. (which is combinated with) crossed extensor reflex. Some interneurons excitatory some inhibitory. Get excitation of flexor and inhibitory to other extensor
Describe GTO reflex
GTO reflex/inverse myotatic. Inhibitory compared to muscle spindle which isnt. something heavy/prevent damage due to overwork. Fin control of muscle tension.
