Session 3 - Anatomy Of The Gastrointestinal System Flashcards
What are the four layers of the gut wall?
Mucosa (innermost)
Submucosa
External muscle layers
Serosa (outermost)
What layers make up the mucosa of the gut wall?
Epithelial layer
Lamina propria
Muscularis mucosae
What does the lamina propria contain?
Lots of lymphoid nodules and macrophages. Produce antibodies to protect against bacterial/viral invasion.
What does the submucosa of the gut wall contain?
Dense connective tissue, blood vessels, glands, lymphoid tissue, submucosal plexus (Meissner’s)
What is a enterocyte?
A simple columnar cell that absorbs. Predominant cell of small and large intestines. Has microvilli.
What do goblet cells secrete?
Mucus
Is there a greater number of goblet cells in the duodenum or colon?
Colon. Increasing number as you move from the duodenum to the colon.
What does mucus protect epithelium from?
Friction (mucus acts as a lubricant) Chemical damage (acidic environment) Bacterial inflammation (forms physical barrier)
What do gastric surface mucous cells (foveolar cells) secrete?
Mucus/HCO3 that forms barrier to stomach acid
What is the difference between plicae circulares and rugae?
Plicae circulares are permanent folds found in the small intestine. Rugae are temporary folds found in the stomach (allow stomach to expand easily).
What specialised cells are found in the crypts of lieberkuhn and what are their functions?
Stem cells -constantly divide to replace epithelia
Paneth cells - secrete antibacterial proteins to protect stem cells
Enteroendocrine cells - secrete hormones that control the function of the gut
Where are crypts of lieberkuhn found?
Small and large intestine
Where are Brunners glands found?
Duodenum
Give examples of exocrine tissues in the gut.
Salivary glands
Pancreas
Brunners glands
What causes ulceration of the GI tract?
Erosion through the muscularis mucosae due to failure of protective mechanisms. E.g. loss of mucus production
What is coeliac disease?
An abnormal immune response to gliadin (protein found in gluten). Mucosa of intestine becomes inflamed and damaged, villi can’t absorb. Results in malabsorption and diarrhoea.