Gastrointestinal System: Anatomy and Physiology

Introduction

• Importance of understanding GI system for nursing care.
• Learning requires active participation and reflection.
• Encouragement to think from both healthcare provider and patient perspectives.

Learning Objectives

• Gain knowledge of GI organs and their functions.
• Understand processes of digestion and their physiological basis.

Overview of GI System

• Anatomy Overview: Mouth, teeth, tongue, salivary glands, external anal sphincter.
• Accessory Organs: Liver, gallbladder, pancreas.
• Nervous System Influence: Parasympathetic nervous system oversees digestion.

Digestive Processes

1. Ingestion
   • Controlled intake of food and drink.
2. Propulsion
   • Movement of food through the GI tract (peristalsis).
3. Digestion
   • Mechanical (chewing, churning) and chemical (enzymes, acids).
4. Absorption
   • Nutrients absorbed in the intestines.
5. Elimination
   • Removal of waste material through stool.

GI System Breakdown

Upper GI Tract

• Mouth to Duodenum
  • Saliva: 1.5L/day (water, mucus, enzymes).
  • Salivary amylase begins chemical digestion.
  • Esophagus: Propels food bolus to stomach.

Stomach

• Secretes acids (2.4L/day) and enzymes for chemical breakdown.
• Mechanical mixing and propulsion through pyloric sphincter to duodenum.

Small Intestine

• Sections: Duodenum, jejunum, ileum (20 ft total).
• Enzymes: Maltase, sucrase, lactase; bile salts from liver/gallbladder.
• Most nutrients absorbed here.
• Villi increase absorption surface area.

Large Intestine

• Colon Sections: Cecum, ascending, transverse, descending, sigmoid, anal canal.
• Reabsorbs water, electrolytes; forms stool for elimination.

Accessory Organs

• Liver: Produces bile (500-1,000 mL/day) for fat breakdown.
• Gallbladder: Stores/concentrates bile, releases into duodenum.
• Pancreas: Exocrine functions - secretes digestive enzymes (amylase, protease, lipase).

Elimination

• Stool moved to rectum by peristalsis triggers defecation reflex.

Clinical Considerations

• Impact of conditions like paralytic ileus, constipation, small bowel obstruction on GI function.
• Role of liver, gallbladder, pancreas in digestion and potential impact of their diseases.
• Importance of proper chewing and food breakdown for nutrient absorption.

Study and Review

• Review anatomical parts, digestive processes, and associated enzymes.
• Test understanding, fill knowledge gaps through additional resources.

Conclusion

• Understand GI system's role in health and patient care.
• Continuous review and application of knowledge in clinical settings.