Small intestine disease

Jejunum - - - Jejunum and Ileum Figure

• 40% of small intestine
• Few large vascular arcades (loops)
• Long vasa recta
• Large, tall, and closely packed plicae circulares
• Less fat in mesentery than ileum
• Locus of maximum water (90%) and nutrient absorption, except for B12, bile acids, iron, and folate
• 95% of water absorbed

• Ileum - - - Jejunum and Ileum Figure

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  60% of small intestine Many small vascular arcades (loops) Short vasa recta Large, low, and sparse plicae circulares, none distal More fat in mesentery than jejunum Maximum absorption of nonconjugated bile acids, with conjugated bile acids absorbed in terminal ileum B12 and folate maximally absorbed in terminal ileum Endocrine Gut Functions Top Cholecystokinin (CCK): secreted by cells of proximal intestine Secretin: secreted by S cells of proximal intestine Motilin: secreted by M cells of proximal intestine Somatostatin (SMS): secreted by D cells throughout gut Peptide YY (PYY): secreted by L cells of distal intestine Glucagon-like peptide 2 (GLP-2): secreted by L cells of distal intestine   Diverticulectomy: most common treatment for uncomplicated diverticulitis Segmental resection indicated for complicated diverticulitis, neck <1/3 ileal diameter, or inflammation of the base