<prompt> Normal lower oesophageal sphincter pressure is5-8 mm of Hg10-25 mm of Hg25 - 40 mm of Hg40 mm of Hg  <response>: The normal lower oesophageal sphincter is 3-4 cm in length and has a pressure of 10-25 mmHgThe LOS is a zone of relatively high pressure that prevents gastric contents from refluxing into the lower oesophagusRef: Bailey and Love 27e pg: 1068 