Anatomy and Cell Biology 3309 Lecture Notes - Lecture 18: Simple Columnar Epithelium, Intestinal Villus, Lamina Propria
22 May 2018
School
Department
Professor
Histology 3309
Intestines
Learning Objectives
1. Differentiate between the stomach, small intestine, and large intestine using histological
markers
2. Distinguish between plicae circulares, intestinal villi, and intestinal crypts
3. List 4 ways in which the surface area of the intestinal tract is increased for absorption
4. Describe the functions and locations of 4 cell types in the intestinal epithelium
5. Outline the principles of lipid, protein, and carbohydrate absorption
6. List histological features that distinguish the duodenum, ileum, and jejunum
7. Explain the immunological significant of Peyer’s Patches
8. Differentiate between cell renewal in the stomach, and in the small intestine
General Organization of GI
Gastroduodenal Junction
- Low magnification
- Can see glands in the submucosa in the duodenum
- The part in the center is pylorus region of stomach (smooth muscle) – so the sphincter will have
smooth muscle
- Yellow box:
o Looking at just the mucosal layer, the duodenum will have microvilli – lined with simple
columnar epithelium with goblet cells
o Fingerlike projections into lumen
- Red box:
o Stomach
o Lined with simple columnar epithelium
o No finger like projections
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find more resources at oneclass.com
- Black box:
o This is the submucosa of stomach– shows smooth muscle (part of the pylorus)
- Blue box:
o Submucosa of the duodenum – shows glands
Main Function = Absorption!
- Increased SA
- The small intestine is about 20ft long
- Large intestine is 5 ft long
- there are different ways that our body increases SA to be able
to reduce the actual length of the intestine that needs to do
that same absorption
- plicae circularis:
o folds of the submucosa which will we see protruding
within the lumen of the intestine
- looking at the tissue, it has a velvet appearance
- this is due to the villi
o villi lined with the intestinal epithelium (simple columnar epithelium)
- each cell of the epithelium will have microvilli
o tiny projections on top of the cell to help further increase SA (to increase absorption
capacity)
- on top of that, there is a layer that is secreted called the glycocalyx (glycolipid and glycoprotein
based)
o this also increases the SA for absorption
o this can only be seen under the EM
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find more resources at oneclass.com
Villi
- each villus has a particular structure
- they are lined by the epithelium
- at its core, they have a lacteal (specialized lymphatic
vessels that allows for the transport of fatty
substances)
- on each side of this, we find an arteriole and venule
that allows for nutrient transport to the systemic
circulation
- at the base of the villi, we find the intestinal glands
(aka cryp of lieberkuhn)
Villi – Longitudinal
- shows lacteal in the middle
- you can also see a little lining around the lacteal
- can also see some smooth muscle within the core of the villus – usually derived from the
muscularis mucosa (help contract the lacteal to be abel to move the lymph from the villus)
- so the epithelium is sitting on the lamina propria (which contains fibroblasts, plasma cells,
macrophages, lymphocytes etc)
Villi – Cross-section
- see lacteal in the center
- may see RBCs within the arteriole or the venule
- also see the epithelium lining the lamina propria
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Can see glands in the submucosa in the duodenum. The part in the center is pylorus region of stomach (smooth muscle) so the sphincter will have smooth muscle. Yellow box: looking at just the mucosal layer, the duodenum will have microvilli lined with simple columnar epithelium with goblet cells, fingerlike projections into lumen. Red box: stomach, lined with simple columnar epithelium, no finger like projections. Blue box: this is the submucosa of stomach shows smooth muscle (part of the pylorus, submucosa of the duodenum shows glands. The small intestine is about 20ft long. Large intestine is 5 ft long there are different ways that our body increases sa to be able to reduce the actual length of the intestine that needs to do that same absorption. Villi cross-section see lacteal in the center. May see rbcs within the arteriole or the venule also see the epithelium lining the lamina propria.
