What Is the Process of Forcing Food Back Up the Esophagus So It Can Be Chewed Again Called
Stages of swallowing (deglutition)
Swallowing, or deglutition, is a circuitous reflex machinery past which food is pushed from the rima oris into the esophagus and so pushed to the breadbasket.
This movement of nutrient from the oral cavity on to the esophagus and stomach by pushing is called propulsion, and information technology is an of import part of the digestive process.
This commodity will overview and detail the 3 phases of swallowing (oral phase, pharyngeal stage, and esophageal stage), including muscles involved, innervation, and clinical aspects.
| Oral phase | Bolus moves from oral crenel into the oropharynx; voluntary process |
| Pharyngeal phase | Bolus moves from the oropharynx into the esophagus; involuntary process |
| Esophageal stage | Bolus moves through the esophagus and into the stomach; involuntary process |
Contents
- Overview
- Stages of swallowing
- Oral phase
- Pharyngeal phase
- Esophageal phase
- Clinical aspects
- Sources
+ Bear witness all
Overview
To understand swallowing, we must first sympathize the digestive procedure. Recall that the digestive system is made upwards of organs that tin can be classified into two groups, the alimentary canal (or gastrointestinal tract), and accessory digestive organs. All of these organs have a particular function, and work together to process nutrient. There are six essential activities involved in the processing of food:
- Ingestion – taking nutrient into the oral crenel, i.east. eating
- Propulsion – moving food through the alimentary canal, including swallowing and peristalsis
- Mechanical breakdown – including mastication (chewing), food churning in the stomach and partitioning
- Digestion – the suspension down of complex food molecules into its chemical components past secreted enzymes
- Absorption – the uptake of digested products (carbohydrates, proteins, lipids, and also vitamins, minerals and water) from the alimentary canal and into the blood or lymph
- Defecation – the excretion of boxy substances from the body
Stages of swallowing
The procedure of swallowing is an essential part of the digestive process. Food is start ingested into the mouth and and then cleaved downwards in the rima oris past chewing, or mastication, tongue movements, saliva, and teeth grinding until it becomes a bolus, a soft mass. The food bolus is soft plenty that it can easily exist swallowed and propelled through the gastrointestinal tract.
In one case food is swallowed, from the mouth information technology moves into the oropharynx, laryngopharynx, and and then passes into the esophagus and into the tummy. Food is propelled in this management by peristalsis, or peristaltic contractions; these are alternate involuntary contractions and relaxations of smooth muscle surrounding the digestive tract. Wrinkle happens before the bolus to propel information technology on, while muscle subsequently the bolus relaxes to permit to bolus room to pass.
This complex procedure of swallowing involves the coordination of 22 different muscle groups, involving the oral crenel, throat, and esophagus. Swallowing is divided into iii stages:
- Oral phase – voluntary, motility of the bolus from the oral crenel into the oropharynx
- Pharyngeal stage – involuntary, movement of the bolus from the oropharynx into the esophagus
- Esophageal phase – involuntary, movement of the bolus through the esophagus and into the stomach
Oral phase
The oral phase of swallowing is the first stage of deglutition, and it is a voluntary process. It is also commonly known as the buccal phase. It involves the contraction of the natural language to push the bolus up against the soft palate and then posteriorly into the oropharynx by both the tongue and the soft palate.
The force per unit area that the food bolus places on the posterior oropharynx activates the oropharyngeal sensory receptors of the glossopharyngeal nerve (CN IX), which then send signals to the solitary nucleus in the swallowing center located in the lower pons and medulla oblongata of the brainstem. The swallowing center and so outputs signals to initial and control the next two phases of swallowing, the pharyngeal phase and the esophageal phase. During the oral phase, the upper esophageal sphincter is closed, and nutrient will non exist able to pass in the esophagus until information technology is open up.
Pharyngeal stage
Adjacent is the pharyngeal phase of swallowing. Dissimilar the oral phase, the pharyngeal stage is an involuntary process. First, the tongue is blocking the mouth. Then, the nasopharynx is sealed off from the oropharynx and laryngopharynx by pinnacle of the soft palate and its uvula. The pharynx will and then receive the bolus later shortening and widening, at the same fourth dimension, the larynx will elevate considering of the contraction of suprahyoid muscles and longitudinal pharyngeal muscles resulting in the epiglottis blocking the trachea. Finally, the upper esophageal sphincter relaxes and opens, assuasive food to enter the esophagus.
During this phase, respiration is inhibited, and the epiglottis blocks off the upper airway to preclude the nutrient bolus and liquids from entering the airway and being inhaled. If food does enter the airway, the cough reflex is triggered. This can happen if someone talks or inhales while swallowing.
The pharyngeal phase is under autonomic control of the swallowing center located in the lower pons and medulla oblongata of the brainstem. More specifically, the nucleus ambiguus in the reticular formation is part of the swallowing center, and it is responsible for generating full general somatic efferent signals.
These nerve impulses are transmitted through various cranial nerves to innervate the skeletal muscles of the pharynx and upper esophagus that are involved in the pharyngeal stage of swallowing. It is principally the vagus nerve (CN X) which transmits these nerve impulses, but five other cranial nerves are as well involved in pharyngeal stage activity: the trigeminal nerve (CN V), the facial nerve (CN 7) the glossopharyngeal nervus (IX), the accessory nerve (CN XI), and the hypoglossal nervus (CN XII).
Esophageal stage
The final stage of deglutition is the esophageal stage. Like the pharyngeal phase, this process is involuntary. The nutrient bolus is forced inferiorly from the pharynx into the esophagus subsequently the sequential contraction of the three pharyngeal constrictor muscles (the superior, middle and junior constrictor muscles), which together make up the external circular layer of the pharynx. This muscle contraction creates a peristaltic ridge. Once the food bolus has fully entered the esophagus, the upper esophageal sphincter volition contract and shut once more.
The food bolus then moves through the esophagus via peristalsis, the sequential contractions of adjacent smooth musculus to propel food in one management. Gravity as well aids in the movement of food to the stomach. The esophagus pierces the diaphragm at the esophageal hiatus, and continues to join the stomach at the cardiac orifice, which is surrounded by the lower esophageal sphincter. It is also known as the gastroesophageal sphincter or cardiac sphincter.
Equally the bolus approaches the stomach, the lower esophageal sphincter effectually the cardiac orifice volition open up and allow the food bolus to pass into the stomach. One time the bolus has entered, the lower esophageal sphincter will close to preclude regurgitation of stomach contents therefore protecting the esophagus from acid reflux.
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Clinical aspects
Harm to any of the muscles and fretfulness involved in swallowing can pb to dysfunction in the stages of swallowing.
Oral phase dysfunction can occur if the patient has problems with tongue innervation. Without proper tongue movements possible, the patient can accept trouble forming a bolus and moving the bolus towards the posterior oropharynx.
If there is dysfunction in the pharyngeal phase, a food bolus or liquids could move through the epiglottis and into the airway if the epiglottis is not sufficiently blocking the upper airway. Substances could and so touch or penetrate the song folds and move into the lungs, this can cause a choking sensation, a change in quality of voice, and shortness of breath.
During the esophageal stage, if the lower esophageal sphincter does not stay contracted, stomach contents tin be regurgitated into the esophagus. This irritates the lining of the esophagus and tin can pb to heartburn, or gastroesophageal reflux.
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