Histology Of The Small And Large Intestine Flashcards
Endocrine secretion happens in the small intestine. True or false? Thank
True
Viewed with the naked eye, the lining of the small intestine shows…
…a series of permanent circular or semilunar folds called plicae circulares
Plicae circulares are composed of…
mucosa and submucosa
Plicae circulares are best developed in the
Jejunum
The entire mucosa of the small intestine is covered by…
…short outgrowths called villi
What are intestinal villi?
Mucosal(epithelium plus lamina propria) outgrowths that project into the lumen
Which parts of the mucosa form the villi?
epithelium plus lamina propria
Each villus has a core of loose connective tissue that extends from the lamina propria. True or false?
True
Each villus contains
Fibroblasts Lymphocytes and plasma cells Smooth muscle fibers Fenestrated capillaries A lacteal (a central lymphatic)
Shapes of intestinal villi
In the duodenum, they are leaf-shaped but gradually assume finger-like shapes moving towards the ileum
Intestinal villi are covered by…
…a simple columnar epithelium of absorptive cells (enterocytes) and goblet cells
What are intestinal crypts or crypts of Lieberkükn?
They are small openings of short tubular glands between the villi
The epithelium of each villus is continuous with…
…that of the intervening glands
The epithelium of the intestinal glands contain:
- Absorptive/enterocytes
- Goblet cells,
- Paneth cells,
- Enteroendocrine cells
- Stem cells that give rise to all these cell types
What will you find in the basal half of absorptive cells?
An oval nucleus
At the apex of each absorptive cell is…
…a homogeneous layer called the striated /brush border
When viewed with the electron microscope, the striated border of absorptive cells is seen as…
…a layer of densely packed microvilli covered by glycocalyx
How many microvilli is each absorptive cell estimated to have?
An average of 3000 microvilli
Microvilli greatly increase the area of contact between the intestinal surface and the nutrients. True or false?
True
Total absorptive area of the intestines
200m.square
What absorb the nutrient molecules produced by digestion?
Enterocytes
Which cells are interspersed between the absorptive cells?
Goblet cells
Goblet cells are less abundant in the ___ but are abundant in the ____?
They are less abundant in the duodenum and more numerous in the ileum
Which cells produce glycoprotein mucins that are hydrated to form mucus to protect and lubricate the lining of the small intestine?
Goblet cells
Paneth cells are exocrine cells with large eosinophilic secretory granules. True or false?
True