Reflex Arc
In a reflex arc, a series of physiological steps occur very rapidly to produce a reflex. Generally a sensory receptor receives an environmental stimulus, in this case from objects reaching nerves in the back of your throat, and sends a message via an afferent nerve to the central nervous system (CNS). The CNS receives this message and sends an appropriate response via an efferent nerve (also known as a motor neuron) to effector cells located in the same initial area that can then carry out the appropriate response.
In the case of the pharyngeal reflex, The sensory limb is mediated predominantly by CNIX (glossopharyngeal nerve), the motor limb by CN X (vagus nerve). The gag reflex involves a brisk and brief elevation of the soft palate and bilateral contraction of pharyngeal muscles evoked by touching the posterior pharyngeal wall. Touching the soft palate can lead to a similar reflex response. However, in that case, the sensory limb of the reflex is the CN V (trigeminal nerve). In very sensitive individuals, much more of the brain stem may be involved; a simple gag may enlarge to retching and vomiting in some.
Read more about this topic: Pharyngeal Reflex
Famous quotes containing the words reflex and/or arc:
“No sooner does a great man depart, and leave his character as public property, than a crowd of little men rushes towards it. There they are gathered together, blinking up to it with such vision as they have, scanning it from afar, hovering round it this way and that, each cunningly endeavouring, by all arts, to catch some reflex of it in the little mirror of himself.”
—Thomas Carlyle (1795–1881)
“You say that you are my judge; I do not know if you are; but take good heed not to judge me ill, because you would put yourself in great peril.”
—Joan Of Arc (c.1412–1431)