Biology 3rd Edition by Peter Russell, Paul Hertz, Beverly McMillan

Exercise 1

The pH of human stomach acid ranges from 1.0 tO₃.0, whereas a healthy esophagus has a pH of approximately 7.0.In gastroesophageal reflux disease (GERD)often called acid reflux, stomach acid flows backward from the stomach into the esophagus.Repeated episodes in which esophageal pH goes below 4.0, considered clinical acid reflux, can result in bleeding ulcers and damage to the esophageal lining.The data in the Figure, from a patient with GERD, show esophageal pH during a sleeping reflux event. 11eb5caa_27f4_9c82_9f04_2361a1fd8b42
How many minutes does it take to go from the peak of the reflux event (when pH is most acidic) to when the reflux event is over?