Lesson plan
Adventitia
The adventitia ( ) is the outer layer of fibrous connective tissue surrounding an organ. The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the tunica adventitia. To some degree, its role is complementary to that of the serosa, which also provides a layer of tissue surrounding an organ. In the abdomen, whether an organ is covered in adventitia or serosa depends upon whether it is peritoneal or retroperitoneal: * intraperitoneal organs are covered in serosa (a layer of mesothelium, the visceral peritoneum) * retroperitoneal organs are covered in adventitia (loose connective tissue) In the gastrointestinal tract, the muscular layer is bounded in most cases by serosa. However, at the oral cavity, thoracic esophagus, ascending colon, descending colon and the rectum, the muscular layer is instead bounded by adventitia. The muscular layer of the duodenum is bounded by both tissue types. Generally, if it is a part of the digestive tract that is free to move, it is covered by serosa, and if it is relatively rigidly fixed, it is covered by adventitia. The connective tissue of the gallbladder is covered by adventitia where the gallbladder bounds the liver, but by serosa for the rest of its surface.
Article summary
The adventitia ( ) is the outer layer of fibrous connective tissue surrounding an organ. The outer layer of connective tissue that surrounds an artery, or vein – the tunica externa, is also called the tunica adventitia. To some degree, its role is complementary to that of the serosa, which also provides a layer of tissue surrounding an organ. In the abdomen, whether an organ is covered in adventitia or serosa depends upon whether it is peritoneal or retroperitoneal: * intraperitoneal organs are covered in serosa (a layer of mesothelium, the visceral peritoneum) * retroperitoneal organs are covered in adventitia (loose connective tissue) In the gastrointestinal tract, the muscular layer is bounded in most cases by serosa. However, at the oral cavity, thoracic esophagus, ascending colon, descending colon and the rectum, the muscular layer is instead bounded by adventitia. The muscular layer of the duodenum is bounded by both tissue types. Generally, if it is a part of the digestive tract that is free to move, it is covered by serosa, and if it is relatively rigidly fixed, it is covered by adventitia. The connective tissue of the gallbladder is covered by adventitia where the gallbladder bounds the liver, but by serosa for the rest of its surface.
Key claims
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Discussion questions
- Summarise the article in your own words. Which single claim would you verify first, and why?
- Which claim in this article is most likely to be revised as the sources update? How would you check its current status?
- If two sources disagreed about one of these facts, what would you need in order to trust one over the other?
Bibliography
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Key claims and bibliography are generated from the same tracked claims and sources as the article page.