Exam 3 Review:  Chapter 23:  Esophagus

esophagus - The muscular membranous tube, which lies posterior to the trachea, which creates peristaltic waves for the passage of each bolus of food from the pharynx to the stomach; its wall consists of an inner stratified squamous epithelium, a lamina propria of loose fibrous connective tissue, a muscularis, and an adventitia.

adventitia - A loose fibrous connective tissue outer covering of an organ or a blood vessel which is not within a body cavity and therefore is not covered by a serosal membrane; this outer covering simply extends outward until the next organ or structure is encountered.

deglutition - The act or process of swallowing food or liquid; it is a complex process which may be under voluntary or involuntary control; it requires the coordinated contraction of skeletal muscles including the tongue, those in the soft palate, pharynx and throat, and the skeletal and smooth muscle of the esophagus; during swallowing the larynx must shift superiorly and anteriorly in order to prevent food or liquid from accidentally entering the respiratory tree.

peristalsis - The wavelike contractions of the smooth muscles of the alimentary canal = gastrointestinal tract or other tubular structures (e.g., the ureters, the uterine tubes) by which contents are forced onward through the tube; to achieve this movement the smooth muscle is arranged in an inner circular and an outer longitudinal layer which act as an antagonistic pair; it is controlled by the ANS and certain local hormones.

upper esophageal sphincter - The ring-like muscle which separates the pharynx from the esophagus; by remaining closed in its resting state, it prevents air from entering the gastrointestinal tract during inspiration, and protects the airway by preventing the reflux of material from the esophagus into the pharynx; it relaxes during swallowing to allow ingested material to enter the esophagus; it consists of at least three groups of skeletal muscles; it is controlled by the ANS.

lower esophageal sphincter - The ring of smooth muscle fibers at the junction of the esophagus and stomach; by remaining closed except when a bolus of food or liquid is being passed to the cardiac portion of the stomach, it protects the esophageal lining from erosion by preventing the acidic stomach contents from being refluxed into the esophagus; it is controlled by the ANS.  aka gastroesophageal sphincter, cardiac sphincter

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