Gastrointestinal Function and Regulation

Overview of Gastrointestinal Function & Regulation

• The primary function of the gastrointestinal tract is to absorb nutrients and water into the body.
• The meal mixes with secretions from the gastrointestinal tract and organs like the pancreas, gallbladder, and salivary glands.
• The gastrointestinal tract includes the mouth, esophagus, stomach, duodenum, jejunum, ileum, cecum, colon, rectum, and anus.

Gastrointestinal Secretions

Salivary Secretion

• Saliva is the first secretion encountered during digestion, produced by three pairs of salivary glands (parotid, submandibular, and sublingual glands).
• Saliva has organic constituents that initiate digestion (starch breakdown by amylase) and protect the oral cavity from bacteria (immunoglobulin A and lysozyme).
• Salivary secretions differ in proteinaceous and mucinous components based on the number of serous and mucous salivary acinar cells.
• Saliva is hypotonic and alkaline, neutralizing gastric secretions that reflux into the esophagus.
• Salivary secretion is controlled by neural influences, primarily the parasympathetic branch of the autonomic nervous system, with slight modifications by sympathetic input.
• Saliva facilitates swallowing, keeps the mouth moist, serves as a solvent for taste buds, aids speech, and keeps the mouth and teeth clean.