Gastrointestinal Tract Flashcards

Large Intestine (Colon)

• Lacks villi and plicae, featuring only crypts.
• Structured with the same layers: epithelium, lamina propria, and muscularis.
• Teniae coli consist of evenly spaced bands of the outer longitudinal layer of muscularis externa.

Teniae coli Functions

• Facilitates contraction of the large intestine.
• Enables segments of the colon to contract independently.
• Contributes to fecal compaction and general peristalsis.

Haustra coli

• Sacculations occurring between teniae coli, allowing parts of the colon to function independently.

Function of the Colon

• Principal role includes the recovery of water and salts.
• Employs Na+/K+ activated ATPase-driven transport system for fat-soluble substances.
• Bacterial activity generates vitamins and results in large amounts of white blood cells.
• Displays a thin muscularis mucosae and thick muscularis externa.

Hirschsprung's Disease (Mega-colon)

• Congenital disorder characterized by the absence of ganglion cells, leading to chronic constipation due to non-migrated neural crest ganglia.

Appendix

• A thin, finger-like blind extension of the colon stemming from the embryonic cecum.
• Lacks villi; contains crypts of Lieberkuhn with columnar and goblet cells.
• Rich in extensive lymphoid tissue and large lymphatic aggregates.
• Features a thick submucosa.

Appendicitis

• Occurs due to obstruction of the opening between the cecum and the appendix.

Carcinoid Tumors

• Arise from enteroendocrine cells; typically found in the gastrointestinal tract.

Peyer's Patches vs. Lymphatic Nodules

• Peyer's patches in the ileum are located anti-mesenteric (on one side), while large lymphatic nodules in the appendix surround the entire structure.

Rectum

• Features thick mucosa and simple columnar epithelium.
• Contains prominent veins and long crypts primarily composed of goblet cells.

Anus

• Composed of stratified squamous epithelium and contains prominent veins.
• Similar to the rectum, it has long crypts with a predominance of goblet cells.

Summary of Digestive Functions

• Digestive processes include absorption, digestion, and waste elimination, with notable roles played by each component of the gastrointestinal tract.