Extrinsic and intrinsic components for the GEJHPZ in seven GERD patients compared with that of non-GERD subjects. Panel A shows the ensemble averaged pressure curve in full expiration from seven GERD patients. Panel B shows the ensemble averaged pressure curve in full expiration. The x axis represents the relative distance from the start of right crural diaphragm, and the y axis represents the pressures relative to the gastric pressures. The red curve is the preatropine pressure profile, the green curve is the postatropine pressure profile and the blue curve is the subtraction profile (red curve minus green curve). Note that in the subtraction curve (blue), the proximal intrinsic muscarinic pressure peak is present in the GERD patients and is in the same axial position relative to the RCd as in the normal volunteers as demonstrated by the rose-colored vertical line on the right. However, the magnitude of this pressure peak is less in the GERD patients. In GERD patients, the distal intrinsic muscarinic peak is absent, as demonstrated by the light turquoise-colored line and box on the left (missing distal peak).