The interplay between chemical species transport and reactions is pivotal in the pathogenesis of GI diseases. In inflammatory bowel disease (IBD), impaired diffusion of anti-inflammatory agents can exacerbate inflammation, while abnormal peristaltic activity can lead to dysregulated convective transport and heightened disease symptoms . The failure of adequate chemical species transport and transformation can disrupt the biophysical stability of the GI tract, contributing to the pathogenesis of diseases such as colorectal cancer and GERD . In GERD, the reflux of acidic gastric contents into the esophagus occurs due to abnormal convective flow resulting from lower esophageal sphincter dysfunction. This acid exposure damages the esophageal epithelium, leading to symptoms and complications such as Barrett's esophagus. The failure of adequate bicarbonate ion diffusion for acid neutralization exacerbates mucosal injury, underscoring the importance of transport and reaction mechanisms . The coupling of nutrient transport with enzymatic reactions facilitates efficient digestion and absorption, while dysregulation can cause malabsorption syndromes . This can be observed in GERD, where transport of protons (H⁺ ions) and their neutralization kinetics are intimately linked to mucosal integrity and injury repair processes . Figure shows a detailed flow chart of the roles of species transport and transformation in the causative mechanisms of GERD. The pathogenesis of GERD commences with transforming food into bolus, which is transported via the esophagus and pharynx. The transport is aided by the peristalsis movement of the esophagus leading the bolus into the gastric unit via the gastroesophageal sphincter (check valve between the esophagus and gastric unit). The bolus is further transformed into chyme in the gastric unit; however, due to the structural weakening of the gastroesophageal or the lower esophageal sphincter caused by ranges of physiological defects (Figure ), a backflow of chyme and other gastric juices such as hydrochloric acid occurs. Over time, the persistent backflow of chyme leads to GERD .