Which of the following prevents GERD: (PGI June 2008)

Ans.: A (LES tone) Anti-Reflux Mechanisms Harrison 17th/1851]LES toneQ: Decreased tone of LES increases the refluxThe Crural diaphragmQAnatomical location of the gastro esophageal junction below the diaphragmatic hiatusCauses of Reflux OesophagitisIncreased gastric volume13Gastric content near the gastro-esophageal junctionIncreased gastric pressureA sustained hypotension of the LES" may be due to muscle weakness that is often without apparent cause.Secondary causes of sustained LES incompetence include scleroderma-like diseases% myopathy associated with chronic intestinal pseudo-obstruction, pregnancy, smoking, anticholinergic drugs , smooth-muscle relaxants (b-adrenergic agents, aminophylline, nitrates , calcium channel blockers, and phosphodiesterase inhibitors), surgical damage to the LES, and esophagitis .Apart from incompetent barriers, gastric contents are most likely to reflux (1) when gastric volume is increased (after meals, in pyloric obstruction, in gastric stasis, during acid hypersecretion states), (2) when gastric contents are near the gastroesophageal junction (in recumbency, bendingdown, hiatal hernia), and (3) when gastric pressure is increased (obesity, pregnancy, ascites, tight clothes) .Incompetence of the diaphragmatic crural muscle, which surrounds the esophageal hiatus in the diaphragm and functions as an external LES, also predisposes to GERD. Obesity;; is a risk factor for GERD.