5.3.1 Gastroesophageal Reflux Disease
Gastroesophageal reflux disease（GERD）is a condition in which reflux of gastric contents into the esophagus produces frequent or severe symptoms that negatively affect the individual’s quality of life or result in damage to the esophagus，pharynx，or the respiratory tract.
The typical presentation of GERD is chest burning（often referred to as heartburn）and the regurgitation of sour or bitter liquid，sometimes mixed with food，to the throat or mouth.Patients may also have non-burning chest pain and difficult swallowing（dysphagia）.The chest pain is usually located in the middle of the chest and may radiate to the back.Difficult swallowing may be due to abnormal esophageal motility or to an esophageal stricture.Symptoms may also arise from the throat，larynx，or lungs.These atypical reflux symptoms，often referred to as extra-esophageal manifestations of reflux disease，may include sore throat，coughing，increased salivation，and shortness of breath.
Medical treatment of GERD usually begins with dietary and life-style modifications and drug therapy.Because the anti-reflux barrier is usually weak in patients with GERD，gravity is important in keeping gastric contents in the stomach and returning regurgitated material back to the stomach when reflux does occur.Current drug therapy depends on two categories of drugs：those that decrease gastric acidity（acid-suppressing agents）and those that enhance upper gastrointestinal motility（prokinetic agents）.For those who fail to respond to medical treatment，surgical or endoscopic intervention may be appropriate.(https://www.daowen.com)
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Task 3 Define the meaning of each medical term given below.
