74-75) explained that an integral factor in enzymatic digestion is the pH of individual sections of the digestive tract. The highly acidic pH of the stomach’s gastric juice is needed to not only prevent bacterial growth, but to create an optimal environment for it’s enzymes to digest the food (now chyme) received through the cardioesophageal sphincter. The small intestine cannot handle such high pH, therefore when the stomach releases chyme into the small intestines, a signal is sent to the pancreas to release an alkaline substance called “sodium bicarbonate” to neutralize the chime’s acidic pH. Once neutralized, enzyme-rich pancreatic juices (neutral pH) work together with the enzymes of the cells found in the intestinal wall to facilitate digestion of the “three energy nutrients”. Bile (neutral pH) is secreted into the duodenum from the gallbladder (or liver-if someone is without the gallbladder) to emulsify fat for later absorption.
3. Explain the concept of a negative feedback mechanism as it relates to gastric acid secretion. The cycle of this negative feedback mechanism starts when food entering the stomach triggers the release of gastrin from the cells of the stomach wall. Gastrin tells the stomach glands to secrete the elements of hydrochloric acid, thus increasing the pH of the environment to 1.5. Once an optimal pH of 1.5 is reached, the cycle reverses.
The acid stops the release of gastrin, which in turn tells the glands to stop secreting hydrochloric acid. (Whitney & Rolfes, 2013, p. 83, para. 6)
4. What is the difference between pro-biotics and pre-biotics in regard to gastrointestinal tract function? What benefits does a synbiotic provide in the