06. Reflex

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Designates reflex [ 4 ] any behavior of the organization is in response to a particular stimulus without the intervention of consciousness. Most often this is the reaction behavior of motor type (muscle), but it may also be of a different nature: for example glandular.

1. Roles of reflexes:

Reflexes are essential behaviors for the body they are in most cases extremely fast and stereotyped.

They allow us to adapt to different situations especially where the physical integrity of the body is threatened. This is the case especially when immediately and involuntarily removed by hand before we realize it was burned [ 82 ].

2. Nature of reflexes:

Reflexes may be innate or acquired through different life experiences [ 1 ].

Reflexes available are many and varied, but they follow the same principle: Few synaptic relay, which ensures the speed of the reaction.

A reflex ensoriel requires a receiver that picks up the signal, an afferent fiber which leads the signals to the CNS often spinal cord or brain stem. From there will arise a motor impulse will travel along a neuron to stimulate effector (often a muscle) that will react. We call this chain of events: the reflex arc [ 1 , 54 ].

3. The reflex arc:

There is no voluntary control over this reflex arc. That said, there sometimes has fibers which go back to the cerebral cortex to keep us aware of what has been achieved.

When the doctor strikes the patellar ligament [ 57 ] (during a physical exam), the percussion causes elongation of the quadriceps muscle. Muscle spindles [ 3 , 38 , 109 ] therein stretch and transmit a signal to the bone by means of proprioceptive nerve fibers (type A alpha).

These fibers terminate in the anterior horn of the spinal cord [ 1 ] on the dendrites of neurons that contract the quadriceps.

Proprioceptive fibers also activate intermediate neurons that inhibit motoneurons of the antagonist muscle [ 130 , 133 ]. There is then a reaction of knee extension.

4. Reflexes in medicine:

Reflexes are operated clinic, they often tell us about the nature and location of the nerve damage.

Thus, if the patellar reflex is abolished, we know that it is therefore a device failure. If, against it is exaggerated and bright, we conclude then that is a loss of central control of the reflex arc, the achievement is central [ 67 ].