Microscopic anatomy of the Gut, Liver and Pancreas Flashcards
In the image below what does number 1 depict?
- lumen of the GIT
In the image below what does number 2 depict in the 4 layers that is present in the GIT?
- mucosa
- epithelium + lamina propria = mucosa
In the image below what does number 3 depict in the 4 layers that is present in the GIT?
- submucosa
In the image below what does number 4 depict in the 4 layers that is present in the GIT?
- muscularis propria
In the image below what does number 5 depict in the 4 layers that is present in the GIT?
- serous
In the colon the haustra are small segmented pouches of bowel which give the colon its segmented appearance. They are formed by circumferential contraction of the inner muscular layer of the colon. Do the haustra go across thew whole lumen?
- no
- how to determine between large and small intestines
In the small intestines there are circular folds of mucous membrane called the valvulae conniventes. Do these transverse the whole of the small intestines wall?
- yes
- this is how to determine between large and small intestines
When looking at the folds of the colon, does it relate to one gland of something else?
- no
- it is where the submucosa has been folded over
- the mucosa then surrounds the submucosa
What is the major cell type in the glands (crypts) of the large intestines?
- goblet cells
In the histology section of the colon below, what do the numbers 1, 2 and 3 relate to?
1 - lamina propria
2 - muscularis mucosa
3 - gland
If inflammatory cells are found on histology of the colon, are these pathological?
- no, can be normal
- if neutrophil they are always pathological
Although neutrophiuls are always pathological in the colon, does that mean all inflammatory cells are pathological?
- no
- some are always present
What do the glands, epithelia and lamina propria make up?
- mucosa
What are the 4 major componenets of the submucosa?
- fat
- connective tissue
- lymphatics
- blood vessels
What is the muscularis propria composed of?
- muscle
- circular muscle
- longitudinal muscle
In the muscularis propria there are 2 layers of mucsle, what are the layers from closest to the lumen first?
1 - circularis muscles
2 - longitudinal muscles
In the appendix there is one large difference to the histology when comparing it to the colon. What is this?
- contains lymphoid follicles
What are the tenia coli in the colon?
- 3 seperate longitudinal ribbons of smooth muscle
- present on ascending, transverse, descending and sigmoid colons
- they contract causing haustra to shorten and move stool
What is the function of the tenia coli?
- contact to facilitate peristalsis
What are the epiploic appendices also commonly known as the omental appendices?
- peritoneum filled with fat
- protect blood vessels of colon
Although the anal canal contains the majority of the layers as the rest of the GIT, what one layer does it not contain, and instead what is present?
- no serosa/peritoneum
- fat is present instead
Where the anal canal meets the rectum, what happens to the glandular make up of the rectal canal?
- changes from glandular to non-keratinizing squamous epithelium
In the small intestines what 2 layers compose the architecture of the glands?
- crypts (bottom)
- villi
Paneth cells, which are highly specialized secretory epithelial cells located in the small intestinal crypts of Lieberkühn produce dense granules contain an abundance of antimicrobial peptides and immunomodulating proteins that function to regulate the composition of the intestinal flora. Are they located anywhere specifically in the small intestines?
- throughout
- but bottom of crypts
In the ileum and duodenum there are specific names given to the glands. What are the names of these?
- ileum = payers patches
- duodenum = brunners glands
Brunner’s glands are cuboidal epithelium only located in the submucosa of the duodenum. What is their function?
- secrete an alkaline (HCO3-) fluid containing mucin
- protects the mucosa from the acidic stomach contents entering the duodenum
Payers patches are only located in the submucosa of the ileum. What is their function?
- small masses of lymphatic tissue or aggregated lymphoid nodules
- important part of the immune system
In the small intestines, in addition to the villi there is something that is important for absorption (especially fats) and immunity that is not present in the colon. What are these called?
- lymphatic lacteals
What is the name given to crypts in the small intestines?
- crypts of Lieberkuhn
Which are longer the crypts or the villi, and why is this important?
- villi are always longer to help with absorption
- if not then its pathological
- seen in coeliac disease