Chapter Summary

• The gastrointestinal system has four main functions: ingestion, digestion, absorption, and metabolization.
• The small intestine handles 90% of nutrient and water absorption.
• The duodenum is the site for iron absorption and some vitamin B₉ (folate) absorption, but the major site for vitamin B₉ absorption is the jejunum.
• Minerals and vitamins A, D, E, and K are absorbed by the small intestine.
• The last segment of the small intestine, the ileum, is responsible for the absorption of bile salts and vitamin B₁₂ (cobalamin).
• The large intestine has three main functions in digestion overall: absorption of the remaining water and electrolytes, absorption and production of vitamins, and formation and movement of feces to the rectum for elimination.
• The first portion of the large intestine, the ascending colon, removes any remaining water and key nutrients from the indigestible material that passes through it, while solidifying this waste to form stool.
• The nutritional plan for clients with gastrointestinal diseases will include supplementation and higher nutritional intake levels than for a healthy client.
• Challenges to nutritional goals include malabsorption, food allergies, comorbidities, and side effects of the gastrointestinal disease processes.