Session 3 Flashcards
(40 cards)
What are the layers of the gut tube?
- Mucosa (innermost)
- Submucos
- External muscle layer
- Serosa (outer most)
What is the function of the epithelial layer of the mucosal layer?
Epithelia
- Selectively permeable layer
- Facilitate transport and digestion of food
- Promote absorption
- Produce hormones
- Produce mucus
What is the function of the lamina propia of the mucosal layer?
- Lots of lymphoid nodules and macrophages
- Produce antibodies
What is the function of the muscularis mucosa of the mucosal layer?
Lamina propria
- Lots of lymphoid nodules and macrophages
- Production of antibodies
What is the function of sub mucosal layer?
- Contains dense connective tissue, blood vessels, glands, lymphoid tissue
- Contains the submucosal plexus (Meissner’s)
What are the structures in the external muscle layers?
Inner circular muscle - Myenteric (Auerbach’s) plexus
Outer longitudinal muscle
What is the function of the serosa?
- Blood and lymph vessels and adipose tissue
- Continuous with mesenteries
What are the types of epithelia found in the gut?
- Stratified squamous in oesophagus and distal anus
- Simple columnar in stomach, small intestine, colon
What is an enterocyte?
A simple column cell that absorbs
What is the function of the enterocyte?
- Needs to transport nutrients through the apical membrane and basolateral membrane to the blood vessels that lie immediately below it
- Has microvilli to increase its surface area for absorption. (brush border)
What is the function of the goblet cells?
- Produce mucus to protect the epithelia against pathogens
- Keeps some bacteria alive
What are the characteristics features of goblet cells?
Wide top and pushed down base which contains the nucleus.
What is the location of goblet cells?
Scattered between enterocytes in increasing numbers from the duodenum to colon
What is the function of mucus in the gut?
Protects the epithelia from
- Friction (acts as a lubricant)
- Chemical damage (acidic environment)
- Bacterial inflammation (forms physical barrier)
What are gastric mucous cells and what do they do?
Foveolar cells line gastric mucosa and secrete mucous containing bicarbonate to form a barrier to stomach acid
What are the adaptations of the gut tube to incraease it surface area?
Non-flat internal surface
- Permanenet folds
- Villi
- Microvilli
What is the purpose of the rugae?
Stomach needs to be easily expandable
Where can villi be found?
In absorptive areas such as small intestine but not in the collon
Where can crypts be found?
-In the small intestine
What do the crypts contain?
- Stem cells
- Paneth cells
- Enteroendocrine cells
What is the function of the stem cells in the crypts of intestine?
Replace the cells that are lost. in the epithelia every 2-4 days. If not then bowel perforation would occur
What is the function of the paneth cells?
-Located at the base of the crypts and secrete antibacterial proteins to protect stem cells
What are the functions of the enteroendocrine cells?
Secrete hormones that control the function of the gut
- Gastrin
- Cholecystokinin
- Secretin
What are glandular tissues?
Organised secretory cells that are connect to a duct. Can be
- Acini
- Tubular
