microscopic anatomy of the gut Flashcards
What type of mucosal epithelium lines the esophagus?
The esophagus is lined by non-keratinizing squamous epithelium.
What are the features of the mucosal epithelium in the esophagus?
he mucosal epithelium in the esophagus is considered a wear and tear epithelium due to its constant exposure to mechanical stress.
What type of mucosal epithelium lines the stomach?
The stomach is lined by glandular epithelium, which includes columnar and cuboidal cells.
What are the features of the mucosal epithelium in the stomach?
The glandular epithelium of the stomach secretes mucous, enzymes, and hormones with a variety of functions.
What type of mucosal epithelium lines the small bowel?
: The small bowel is lined by glandular epithelium, primarily composed of columnar and goblet cells.
What are the features of the mucosal epithelium in the small bowel?
The mucosal epithelium in the small bowel has a villous architecture, which maximizes the absorptive surface area.
What is the function of the large bowel and rectum?
The large bowel and rectum are involved in the absorption of water and the formation of feces.
What type of mucosal epithelium lines the large bowel and rectum?
: The large bowel and rectum are lined by glandular epithelium, primarily composed of columnar and goblet cells.
What are the features of the mucosal epithelium in the large bowel and rectum?
he mucosal epithelium in the large bowel and rectum has a flat architecture and secretes mucous.
What type of mucosal epithelium lines the anus?
The anus is lined by a mixture of glandular and squamous epithelium.
What are the features of the mucosal epithelium in the anus?
The anus has complex anatomy and sphincter functions, involving both glandular and squamous epithelial components.
What are the key features of the large bowel and rectum?
The large bowel and rectum are the archetypal examples of the gastrointestinal tract. They have the following key features:
Glandular epithelium composed of columnar cells and goblet cells.
Glands in the large bowel and rectum resemble straight test tubes arranged neatly in a rack.
There are some site variations, such as the presence of lymphoid follicles in the appendix.
The anus represents the junction of squamous and glandular mucosa.
What does the mucosa of the colon/rectum consist of?
The mucosa of the colon/rectum consists of two main components: the epithelium and the lamina propria (LP).
The epithelium is composed of columnar cells and goblet cells.
Glands, also known as crypts of Lieberkühn, open onto the luminal surface of the bowel.
The gland bases rest on the muscularis mucosae (MM).
What is the significance of inflammatory cells within the mucosal surface of the colon?
Inflammatory cells within the lamina propria of the colon are considered normal. However, the presence of neutrophils in the mucosal surface is always considered pathological and not typically seen in this picture.
What can be observed at the base of the crypts in the colon?
In the colon, cells appear darker at the base of the crypts. Additionally, scattered neuroendocrine cells can be found in this region.
What is the location of the submucosa in the colon/rectum?
The submucosa (SM) is located between the muscularis propria (MP) and the mucosa (M) in the colon/rectum.
What is the muscular layer responsible for the proper wall of the colon?
: The muscularis propria (MP) is considered the “proper” wall of the colon.
What is the histological appearance of the appendix?
The appendix is a blind-ending tube attached to the base of the cecum. It has the same histological appearance as the large bowel and rectum, with the addition of a variable number of lymphoid follicles.
What are the layers observed in the appendix’s tip?
The layers observed in the tip of the appendix are the lamina propria (LP), submucosa (SM), muscularis propria (MP), and serosa.
What are the layers observed in the appendix’s histology?
The layers observed in the histology of the appendix are the lumen, lamina propria (LP), submucosa (SM), muscularis propria (MP), and serosa.
What are the key features of the anal canal?
The key features of the anal canal include the presence of glandular and non-keratinizing squamous epithelium adjacent to each other, a flat architecture, and the absence of a serosal surface as it lacks peritoneal covering.
What types of epithelium are present in the anal canal?
The anal canal contains both squamous epithelium and glandular epithelium.
What is the transition point between the two types of epithelium in the anal canal?
The transition between squamous epithelium and glandular epithelium in the anal canal occurs roughly at the level of the dentate line, although it may not be a perfect correlation.
What is the histological appearance of the anal mucosa?
The anal mucosa consists of squamous epithelium and glandular epithelium.
What are the key features of the small bowel?
The key features of the small bowel include the presence of glandular epithelium consisting of columnar cells, goblet cells, and Paneth cells. It has a structural architecture characterized by villi and crypts, which maximize the absorptive area. Minor site variations include the presence of Brunner’s glands in the duodenum and Peyer’s patches in the ileum.
What is the histological composition of the small bowel mucosa?
The small bowel mucosa consists of epithelium and lamina propria. The epithelium is composed of columnar cells, goblet cells, and Paneth cells.
What are the structures present in the small bowel villi and crypts?
The small bowel villi are finger-like projections that increase the surface area for absorption. The crypts of Lieberkuhn are invaginations between the villi that contain stem cells for epithelial cell renewal.
What are the functions of Paneth cells in the small bowel?
Paneth cells, present throughout the small bowel, secrete antimicrobial peptides and enzymes involved in the digestion of proteins.
What are lacteals in the small bowel?
Lacteals are blind-ending lymphatic vessels located within each villus of the small bowel. They play a role in the absorption of dietary fats.