Patellar reflex

(This image is taken from the site: https://it.wikipedia.org/wiki/Miastenia_gravis).

Neural circuits represent the organizational unit of the neurons. These circuits are the basis of perceptions and behavior. Synaptic connections along with the dendrites, the axon and glial cells form the neuropil (Parves, Augustine, Fitzpatrick, Hall, LaMantia, White, Neuroscience, Sinauer Associates Inc).

We can distinguish the neuronal circuits depending on the direction followed by electrical impulses. When the flow travels from the periphery to the encephalon or spinal cord there are afferent neurons. When the flow travels in the opposite direction there are efferent neurons.

Interneurons concern local aspects of the circuit.

We can cause patellar reflex beating the leg with a small hammer just after the knee. This stimulates the peripheral sensory receptors. These receptors transmit the information to the afferent sensory neurons. The impulse travels through the axons of these neurons until the spinal cord. Here, the afferent sensory neuron excites the interneuron and efferent motor neuron. The information travels through the axon of efferent neuron. The impulse then reaches the synapses of extensor muscle fibers. This causes the contraction of this muscle.

At the same time the interneuron inhibits the motor neurons of flexor muscle. This information travels down the axon and reaches the synapses of flexor muscle. This results in a relaxation of this muscle (Parves, Augustine, Fitzpatrick, Hall, LaMantia, White, Neuroscience, Sinauer Associates Inc).