Perhaps the most preventable cause of damage to these reflexes originates from smoking. Since both the digestive system and the respiratory system are connected by the pharynx, there are many problems and diseases that occur when the body is unable to regulate passage of food and air into the appropriate tracts. Therefore these reflexes prevent levels reaching this maximum volume. However, if the maximum capacity of fluids that the hypopharynx can safely hold is exceeded, then this excess fluid spills into the larynx and from there into the lungs. The hypopharynx is the bottom part of pharynx, and can be considered the first area where the digestive tract splits from the airways. These reflexes can also protect the airways from any food or liquids that may spill over from the hypopharynx. All either forcibly close the glottis or allow the pharynx to remove particles into the digestive tract that may have been forced back up by both this tract and the upper respiratory tract. This particular reflex is simply one of several aero digestive reflexes such as the reflexive pharyngeal swallow, the pharyngoglottal closure reflex, in which no swallowing occurs yet the glottis still closes, and the pharyngo-upper esophageal sphincter contractile reflex, occurring mainly during gastroesophageal reflux episodes. This reflex in particular functions as a protective system for the upper respiratory tract as it not only forces the glottis to close, thereby preventing any substances getting into the airways, but also clears the pharynx of any residual substances by a swallow. Reflexive Pharyngeal Swallow Ĭlosely related to the gag reflex, in which food or other foreign substances are forced back out of the pharynx, swallowing generally pushes food through the digestive system into the stomach. Pharyngeal sensation, on the other hand, as seen by this study, is rarely absent, and could prove better at predicting future problems with swallowing. Since this reflex is commonly not found in healthy people, its predictive value in determining the risk for swallowing disorders is severely limited. These results suggest that the muscles that control the gag reflex remain independent of those that control normal swallowing. However, in one study, 37% of healthy people did not have a gag reflex, yet all subjects except for one still retained an intact pharyngeal sensation. At one point, it was thought that a lack of the gag reflex in stroke patients was a good predictor for dysphagia (difficulty with swallowing) or laryngeal aspiration (food or drink entering the larynx), and was therefore commonly checked for. Of course, the effectiveness of these techniques varies with the person.Ībsence of the gag reflex and pharyngeal sensation can be a symptom of a number of severe medical conditions, such as damage to the glossopharyngeal nerve, the vagus nerve, or brain death. There are a variety of ways to desensitize one’s hypersensitivity, from relaxation to numbing the mouth and throat to training your soft palate to get used to being touched. Hypersensitivity is generally a conditioned response, usually occurring following a previous experience. This hypersensitivity can lead to a variety of issues, from swallowing a pill or large bites of food to visiting the dentist. However, on the other end of the spectrum are people with a hypersensitive gag reflex. In contrast, triggering the reflex is sometimes done intentionally to induce vomiting, for example by those who suffer from bulimia nervosa.Īccording to one study, one in three people lack a gag reflex. Some people, for instance sword swallowers, have learned how to suppress it. Swallowing unusually large objects or placing objects in the back of the mouth may cause the pharyngeal reflex. The efferent limb is supplied by the vagus nerve (cranial nerve X) from the nucleus ambiguus, also located in the medulla in the brain stem. The afferent limb of this reflex is supplied by the glossopharyngeal nerve (cranial nerve IX), which synapses on the nucleus solitarius and the spinal trigeminal nucleus, both nuclei in the medulla oblongata in the brain stem. 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. 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). In a reflex arc, a series of physiological steps occur very rapidly to produce a reflex.
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