3 - Stomach layers Flashcards
From inner to outer, what are the layers of the GI tract?
Mucosa
Submucosa
External muscle
Serosa
What are the layers of the mucosa?
Epithelial - selectively permeable barrier, allows transport of food, produces hormones and mucus
Lamina propria - Lymphoid nodules and macrophages, produce IgA, resistant proteases
Muscularis mucosae - smooth muscle with different orientations, keeps epithelium in contact with gut contents and keeps crypt contents dynamic, preventing stagnation and inflammation
What is contained in the sub mucosa?
Dense connective tissue
lymph tissue
glands
blood vessels
What is contained in the serosa?
Blood vessels
Lymph vessels
Adipose tissues
Describe the epithelia of the gut
Stratified squamous in the oesophagus and distal anus - resists friction
Simple columnar everywhere else
Where are enterocytes found and what is their function?
Small intestine and colon
Brush border of microvilli to increase surface area, which aids in absorption
Where are goblet cells found and what is their function?
In between enterocytes, increasing in number from duodenum to colon
Produces mucus to protect epithelia from:
Friction (lubricates)
Chemical damage (acid)
Bacterial inflammation (forms a physical barrier)
Where are gastric surface mucous cells found and what is their function?
Line gastric mucosa and gastric pits
Secretes mucus and HCO3 that forms barrier to stomach acid
Where are paneth cells found and what is their function?
At base of crypts
Secrete antibacterial proteins to protect stem cells, secretory vesicles are red
How can crypts be affected by disease processes?
Inflammatory bowel disease:
Crypt alteration
Cryptitis (inflammation of wall)
Crypt abscess (neutrophils in lumen)
Where are enteroendocrine cells and where are they found?
Secrete hormones to control gut function
Predominantly located in crypts and gastric glands
Describe glandular tissue in the gut
Exocrine
Made up of acini - secrete serous and enzymes
and Tubules - Secrete mucous, Brunner’s gland
Connected to ducts
Describe how disease processes affects glandular tissue in the gut
Ulceration - Erodes muscularis mucosae due to failure of mucus production
Coeliac disease - Inability to tolerate gliadin, damages mucosa, leading to poor digestion and malabsorption
IBD - damages crypts
