Sunday 29 March 2020
Wednesday 11 March 2020
Tuesday 10 March 2020
Duodenum, histology, discussion, viva, oral, questions
- What are the four main layers of duodenum?
- From within (lumen) outwards
- Mucosa (mucous membrane)
- Submucosa
- Muscularis externa
- Serosa or adventitia
- What are the layers of mucosa?
- From lumen outwards
- Epithelial lining
- Lamina propria
- Muscularis mucosae
- What is the epithelial lining in duodenum?
- Simple columnar epithelium with striated border and few goblet cells
- What are the modifications of mucosa?
- Plicae circularis, villi, microvilli
- What are the functions of modifications of mucosa?
- Modifications of mucosa increases the surface area of absorption
- What are the components of lamina propria?
- Loose connective tissue
- Blood vessels
- Lymphatics
- Lymphocytes
- Nerves
- Crypts of Leiberkuhn or intestinal glands
- What are crypts of Lieberkuhn?
- Intestinal glands or crypts of Lieberkuhn are the invaginations of surface epithelium (simple columnar epithelium) into lamina propria
- What are lacteals?
- Lacteals are dilated blind ending lymphatic capillary present in the core of lamina propria of the villus
- What are the plicae circularis, villi, microvilli?
- Plicae circularis is the permanent fold of 3 layers of mucosa with core of submucosa
- Villi are the surface projections of epithelial layer with core of lamina propria
- Microvilli are the projections of cell membrane with core of cytoplasm
- Name the different types of cells in intestinal glands.
- Columnar absorptive cells
- Goblet cells
- Enteroendocrine / APUD cells
- Mucous cells
- Undifferentiated cell
- Paneth cells
- Lymphocytes
- M cells
- What is muscularis mucosae?
- Muscularis mucosae is a thin layer of smooth muscle arranged as inner circular and outer longitudinal layers around the lamina propria
- What are the components of submucosa?
- Dense connective tissue
- Larger blood vessels
- Submucosal (Meissner's) plexus of autonomic nerves
- Duodenal or submucosal glands
- What are duodenal glands?
- Duodenal glands also called as submucosal glands present in the submucosa are mucus secreting cells lining the branched tubuloacinar glands
- What are the components of muscularis externa?
- Inner circular smooth muscle layer
- Outer longitudinal smooth muscle layer
- Between outer two layers is thin connective tissue layer with blood vessels, lymph vessels, myenteric (Auerbach's) plexus of autonomic nerves
- What is serosa?
- Serosa- thin layer of loose connective tissue with numerous blood vessels, lymphatics, adipose tissue covered by simple squamous epithelium (mesothelium)
- Difference between serosa and adventitia
Serosa
|
Adventitia
|
Thin
layer of loose connective tissue with numerous blood vessels, lymphatics,
adipose tissue covered by mesothelium (simple squamous epithelium)
|
Loose
connective tissue with numerous blood vessels, lymphatics, adipose tissue
which merges with surrounding tissues. Mesothelium is absent
|
17. What is mesothelium?
- It is a simple squamous epithelium covering a thin layer of loose connective tissue in the abdomen surrounding the viscera
18. What is the function of Meissner's plexus?
- Meissner’s plexus regulates the configuration of the luminal surface, controls glandular secretions, alters electrolyte and water transport and regulates local blood flow
19. What is the function of Myenteric plexus?
- Myenteric plexus supplies the GIT and controls the gastric motility
20. List the characteristic features seen only in duodenum?
- Goblet cells are few
- Villi are tall, broad and numerous
- Duodenal glands in submucosa
21. Name the differences between the duodenum, jejunum and ileum?
|
|
Duodenum |
Jejunum |
Ileum |
|
Mucosa
Epithelium
|
Striated columnar with few goblets cells.
|
Striated columnar with more goblet cells.
|
Striated columnar
with a high number of goblet cells.
|
|
Villi |
Leaf shaped.
|
Tall, tongue shaped.
|
Short, finger shaped.
|
|
Lamina propria |
Crypts with argentaffin cells. Loose lymphatic
tissue.
|
Crypts with less argentaffin cells. Diffuse
lymphatic nodules.
|
Crypts with less argentaffin cells. Lymphatic
nodules aggregated to form Peyer’s patches.
|
|
Muscularis mucosa
|
Continuous.
|
Interrupted.
|
Interrupted.
|
|
Submucosa |
Presence of Brunner’s glands. Connective tissue
with blood vessels and nerves.
|
Connective tissue with blood vessels and nerves.
|
Presence of Peyer’s patches.
Connective tissue with blood vessels and nerves.
|
|
Muscularis
externa
|
Inner circular and outer longitudinal smooth
muscle layers with myenteric
(Auerbach’s) nerve plexus, blood and lymph vessels.
|
Inner circular and outer longitudinal smooth
muscle layers with myenteric
(Auerbach’s) nerve plexus, blood and lymph vessels.
|
Inner circular and outer longitudinal smooth
muscle layers with myenteric
(Auerbach’s) nerve plexus, blood and lymph vessels.
|
|
Serosa |
Loose connective tissue with blood and lymph vessels covered by
mesothelium. |
Loose connective tissue with blood and lymph vessels covered by
mesothelium. |
Loose connective tissue with blood and lymph vessels covered by
mesothelium. |
22. Name the differences between the small intestine and large intestine.
|
|
Small Intestine |
Large Intestine |
|
Mucosa
|
Plicae circularis and villi present.
|
Absent.
|
|
Epithelium
|
Goblet cells less in number and columnar cells
more in number.
|
Goblet cells more in number and few columnar
cells.
|
|
Lamina Propria
|
Crypts of Leiberkuhn are few and consist of
columnar cells, goblet cells, more number of Paneth and argentaffin cells.
|
Crypts are more numerous, deeper and consists of
less number of columnar cells, numerous goblet cells, very rarely Paneth and
argentaffin cells.
|
|
Muscularis mucosa |
Smooth muscle:
inner circular and outer longitudinal layers.
Interrupted in some regions.
|
Smooth muscle: inner circular and outer
longitudinal layers.
|
|
Submucosa |
Irregular connective tissue with large
blood vessels, lymphatic vessels, Meissner’s plexus, glands and lymphatic
tissue in some parts. |
Irregular connective tissue with large blood
vessels, lymphatic vessels, Meissner’s plexus, lymphatic tissue.
|
|
Muscularis
externa
|
Inner circular and outer longitudinal smooth
muscle layers with myenteric
(Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat
uniformly thick.
|
Inner circular and outer longitudinal smooth
muscle layers with myenteric
(Auerbach’s) nerve plexus, blood and lymph vessels. Longitudinal coat,
thickened to form three bands, the taenia coli.
|
|
Serosa
|
Loose connective tissue covered by mesothelium,
has blood and lymph vessels.
|
In some parts absent, which are covered by
adventitia.
|
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