Histology of the Oesophagus and Stomach Flashcards
Type of muscle in each 1/3 of the oesophagus
- Upper = striated (skeletal)
- Middle = mix
- Lower = smooth
Tissue layers of the oesophagus
- Stratified squamous epithelium
- Lamina propria
- Muscularis mucosa
- Submucosa
- Circular muscles
- Longitudinal muscle
What causes the star-shaped lumen of the oesophagus?
Contraction of the muscularis mucosa creating longitudinal mucosal folds
What glands are found in the oesophageal submucosa and what is their function?
- Submucosal (accessory salivary)
- Make secretion to lubricate mucosal surface
What is the epithelial change at the gastro-oesophageal junction?
Stratified squamous –> simple columnar
4 macroscopic regions of the stomach
- Cardia (surrounding oesophageal orifice (OO))
- Fundus (above horizontal line from OO)
- Body (below line)
- Pyloric antrum (surrounding pylorus)
3 histological regions of the stomach
- Cardiac region
- Pyloric region
- Fundic region
What glands are found in the fundic region of the stomach?
Fundic/gastric glands
Components of the gastric gland and their function
- Pit = entrance to gland
- Neck = where branching can occur
- Deep zone = where acid/enzyme/hormones are made
2 types of cell in the pit/neck of a gastric gland, and what they do
- Surface mucous cell (simple columnar)
- Neck mucous cell
- Secrete mucous
What does the gastric mucosa contain to give it its protective function?
Lots of HCO3-
3 types of cell in the deep zone of a gastric gland and their functions
- Parietal cells (secrete HCl + intrinsic factor)
- Chief cells (enzyme secretion)
- Enteroendocrine cells (secrete hormones)
What does intrinsic factor play a role in?
Absorption of vitamin B12
What cells are found in the isthmus (just above neck) of a gastric gland, and what is their function?
Undifferentiated stem cells (replace cells above or below)
Which cells dominate the cardiac and pyloric regions of the stomach?
Columnar mucous cells
What stimulates chief cells in gastric glands?
ACh
What is secreted by chief cells in a gastric gland, and what does this become and how?
Pepsinogen (HCl converts to pepsin)
What does a lack of intrinsic factor cause?
Pernicious anaemia
Organisation of organelles in a gastric chief cell
- Lots of rER in basal portion
- Secretory vesicles containing pepsinogen in apical portion
What adapted structure is found in gastric parietal cells and what is its function?
- Secretory intracellular canaliculus
- Increases surface area
Which enzymes are found in the secretory canaliculus and why?
- Carbonic anhydrase (make HCO3- for transfer of Cl-)
- H+/K+ ATPase (for transfer of H+)
- H+ + Cl- –> HCl
