Page 613 - Atlas of Histology with Functional Correlations

Digestive System Part III: Small Intestine and

Large Intestine

SMALL INTESTINE

Long, convoluted tube divided into duodenum, jejunum, and ileum
Duodenum is the shortest segment with broad, tall, and numerous villi
Digests gastric contents and absorbs nutrients into blood capillaries and

lymphatic lacteals
Transports chyme and waste products to large intestine
Releases numerous hormones to regulate secretory functions and motility of
digestive organs
Amino acids, water, ions, glucose, and other substances are absorbed and

transported in blood capillaries
Long-chain fatty acids and monoglycerides are transported by lymphatic
lacteals

Contains numerous permanent surface modifications that increase cellular
contact for absorption
Plicae circulares are spiral folds with submucosa core that extend into
intestinal lumen
Villi are finger-like projections of lamina propria that extend into the

intestinal lumen
Microvilli are cytoplasmic extensions of absorptive cells that extend into the
intestinal lumen

Microvilli are coated with brush border enzymes that perform the final
digestion of food products before absorption
Villi contain a core of connective tissue with capillaries, lacteal, and smooth
muscle strands
Lamina propria is filled with lymphocytes, plasma cells, macrophages,

eosinophils, and mast cells
Smooth muscle strands in lamina propria of villi induce their movement and
contractions

Cells of the Small Intestine

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