Esophagus & Stomach Flashcards
Esophagus is?
Muscular tube modified for transport of food to and from stomach
Esophagus characteristics
Flexible and distensible
4 layers of esophagus
- Mucosa
- Submucosa
- Muscularis externa
- Adventitia
Cells of esophageal t. mucosa
Stratified squamous epithelium (non-keratinized in carnivores)
2 layers of esophageal t. mucosa
- Lamina propria
2. Mucularis mucosa
Esophageal muscularis mucosa is composed of?
Smooth muscle fibers
Esophageal muscularis mucosa fibers run?
Parallel to tube
Submucosal glands are only found in?
- Esophagus
2. Duodenum
Esophageal t. muscularis consists of?
2 layers of skeletal muscle fibers
2 layers of esophageal t. muscularis
- Inner circular
2. Outher longitudinal
Muscularis mucosa in cervical region of esophagus
Absent
Functions of esophageal t. muscularis
Vomiting, regurgitation
Stomach digestion
Mechanical and chemical
Non-glandular region of stomach
Esophageal region
Glandular regions of stomach
- Cardia
- Fundus
- Pylorus
Cells of esophageal region of stomach
Stratified squamous epithelium
Margo plicatus
Raised transitional line from non-glandular to glandular stomach
Non-glandular region in ruminants might be called?
Forestomach
Ruminant forestomach also called?
Proventriculus
3 parts of ruminant proventriculus
- Rumen
- Reticulum
- Omasum
Proventriculus cells
Stratified squamous keratinized epithelium
Rumen also called?
Paunch
Ruminal lumen
- Has conical papillae
- No muscular tissue carried into ruminal papillae
- Pillars and grooves (“shag carpet”)
Reticulum also called?
Honeycomb
How does reticulum form honeycomb pattern?
Tunica mucosa forms ridges covered with papillae
Reticular folds have?
Band of smooth m. at tip
Cells of reticulum
Stratified squamous epithelium with keratinization
Tunica mucosa in omasum forms?
Laminae (long folds)
Cardia
Transitional zone between esophagus nd stomach
Gastric acid is produced in what regions of stomach?
- Fundus
2. Body
Pylorus
Funnel shaped region open into SI
4 layers of glandular stomach
- Mucosa
- Submucosa
- Muscularis externa
- Serosa
Rugae of glandular stomach are formed by?
Mucosa and submucosa folds
Rugae of glandular stomach flattens when?
Stomach fills
Mucosal epithelium of stomach
Simple columnar (mucus secreting)
Gastric pits are?
Epithelium invaginations into lamina propria
Cells lining surface of stomach mucosa are called?
Surface mucuous cells
Gastric glands of mucosa open into?
Gastric pits
Cells of cardiac region
Transition from stratified squamous to simple columnar epithelium
Gastric glands of cardiac region are usualy lined by?
Mucus-secreting cells
Depth of gastric pits in cardiac region
1/3rd of entire lamina propria (medium depth)
Depth of gastric pits in fundic region
4 parts of gastric (fundic) gland
- Isthmus
- Neck
- Body
- Base
Isthmus of gastric gland
Opening of gland into pit above it
Neck of gastric gland
Constricted area near isthmus
Body of gastric gland
Main tube
Base of gastric gland
Dilated adenomere
5 types of cells in fundic glands
- Chief (zymogen) cels
- Parietal (oxyntic) cells
- Mucus neck cells
- Enteroendocrine cells
- Germinal cells
Chief cells are most numerous where?
Lower regions of gland
Chief cell appearance
Foamy/lacy
Stain light blue with H&E
Chief cell shape
Pyramidal
Basally positioned round nucleus
Secretory/zymogen granules in chief cells
- Apically positioned
2. Present in fasted animals
Chief cells secrete?
- Pepsinogen
- Gastric lipase
- Renin in young animals
Pepsinogen is converted to?
Pepsin
Pepsin is?
Proteolytic enzyme in acidic environment
Renin in young animals
Curdles milk by coagulating casein
Parietal cells aka?
Oxyntic cells
Parietal cell cytoplasm
Bright-staining eosinophilic
Parietal cell shape
Large, spheroidal with round nucleus
Parietal cells are found where?
Scattered throughout gastric glands from neck to base, wedged between chief cells
Parietal cells produce?
HCl
Parietal cells are stimulated to produce HCl by?
- Cholinergic nerve endings
- Gastrin
- Histamine
Parietal cells contains?
Intracellular canalicula → extend from apical plasmalemma into cytoplasm
Intracellular canaliculi or parietal cells are occluded by?
Many microvilli
Mucus neck cells?
Line neck of gastric gland
Mucus neck cells are interspersed among?
Parietal cells
How is mucoid product of mucus neck cells different than that of surface mucus cells?
- Less viscous
2. Contain acidic GAGs
GAG stands for?
Glycosaminoglycan
Function of mucuous from mucus neck cells?
Protection from hydrolytic activity of HCl
What are enteroendocrine cells?
Endocrine/paracrine cells within enteric epithelium
Old name of enteroendocrine cells
APUD
APUD stands for?
Amine Precursor Uptake and Decarboxylation activity
DNES stands for?
Diffus neuroendocrine system
Eneroendocrine cells are not limited to the GI but scattered all over the body among endothelial cells, so they are referred to as?
DNES
Enteroendocrine cells stain with silver and chromium stains so they are also referred to as?
- Argentaffin cells
2. Enterochromaffin cells
Examples of enteroendocrine cells
- G cells
- D cells
- EC cells
G cells secrete?
Gastrin
D cels secrete?
Somatostatin
EC cells secrete?
- Seratonin
2. Substance P
Germinal cells are found in?
Gland neck and bottom of pits
Length of gastric pits in pyloric region
1/2 of lamina propria (deepest)
Deepest gastric pits are found in?
Pyloric region
How are gastric pits of pyloric region histologically similar to cardiac gland region?
- Mucus secreting cells
2. Gastrin enteroendocrine cells
Pyloric region contains?
Muscular sphincter at gastroduodenal junction