12 Questions
What is the main function of the small intestine?
Absorption of nutrients
What is the role of plicae circulares in the small intestine?
Increase the surface area for absorption
Which structural feature in the small intestine increases the surface area by a factor of ~ ten?
Intestinal villi
What is the purpose of microvilli in the small intestine?
Increase absorption surface area
Which segment of the small intestine consists of about one-half to two-thirds circumference of plicae circulares?
Jejunum
Which cell type forms numerous microvilli in the epithelium of the small intestine?
Enterocyte
Describe the structural features of the mucosa in the small intestine that significantly increase the luminal surface area.
Plicae circulares and intestinal villi.
What is the function of microvilli in the small intestine?
Microvilli increase the surface area by a factor of ~ 20.
How do plicae circulares contribute to the structure of the small intestine?
Plicae circulares are macroscopically visible crescent-shaped folds that extend around one-half to two-thirds of the circumference of the lumen.
What is the histological organization common to the three segments of the small intestine - duodenum, jejunum, and ileum?
They all have the same basic histological organization.
Which segment of the small intestine is approximately 25-30 cm in length?
Duodenum.
What is the length of the jejunum compared to the rest of the small intestine?
Jejunum is about the first two-fifths of the rest of the small intestine.
Study Notes
Small Intestine Structure
- The small intestine is divided into three segments: duodenum (25-30 cm), jejunum (about first two-fifths of the rest), and ileum.
- The three segments have the same basic histological organization.
Mucosa of Small Intestine
- The mucosa has various structural features that increase the luminal surface area to support the absorption of degraded food components.
- Plicae circulares (of Kerkering) are crescent-shaped folds of the mucosa and submucosa that extend around one-half to two-thirds of the lumen's circumference.
- The entire intestinal mucosa forms intestinal villi, which are about 1 mm long and increase the surface area by a factor of ~10.
- The surface of the villi is formed by a simple columnar epithelium.
Intestinal Villi and Microvilli
- Each absorptive cell (enterocyte) of the epithelium forms numerous microvilli, which are 1 µm long and about 0.1 µm wide.
- Microvilli increase the surface area by a factor of ~20.
- The combined effect of villi and microvilli increases the surface area by a factor of ~200.
Learn about the division and histological organization of the small intestine into duodenum, jejunum, and ileum. Explore the mucosa's structural features that enhance surface area for absorption of digested food components.
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