Reflex Arc bypassing CNS

[MedGrl@2022]

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Does the reflex arc bypass the CNS? Examkrackers says that "the CNS consists of the interneurons and the support tissue within the brain and the spinal cord. The function of the CNS is to integrate nervous signals between the sensory and motor neurons."

Many pictures of the reflex arc show an interneuron between afferent sensory neuron and an efferent motor neurons. It also says that "some reflex arcs do not require an interneuron." Thus, does the reflex arc bypass the CNS?

Thank you for your help.

 

[maseface]

Bypass the CNS? It sounds so technical and I don't think it matters but I would guess that no it does not bypass the CNS. The shortest reflex arcs such as the patellar reflex do not involve interneurons but some other reflexes do. But even if they do not involve interneurons, there still exists a synapse from the afferent neuron to the efferent and this synapse is in the spinal cord.

 

[Drrrrrr. Celty]

It doesn't "Bypass the CNS" as it is still innervating within the Spinal Cord, which is a part of the CNS. However the reflex arc is not an ascending tract, meaning that it does not have to go up to the brain, be processed by the big three ( Motor cortex, Basal Ganglia, Cerebellum) and then come down. But rather it is already a pre-programed "relfex" built into the network in the spinal cord.

Basically and very simply:
Stimuli -> Sensory Neuron activates/ action potentials -> innervation in the spinal cord with the dendrite of a motor neuron or interneuron -> ( If interneuron it innervates with the posture ganglian thingy ( I can't remember what it's called) -< proceeds to a muscle ( Causes calcium to release, causing actin to be free) and causes a motor response.