Histology- Tubular GI Flashcards
Four layers of the wall of the alimentary canal
- Mucosa: Containing epithelium, lamina propria, and muscularis mucosa
- Submucosa: dense conn tissue
- Muscularis Externa: smooth muscle
- Serosa: squamous epithelium
Three principle functions of the mucosal layer?
- Secretion
- Absorption
- Protection
Submucosa functions
Blood and Lymph Vessels are here, nerve plexus, occasional glands
Muscularis external function
contractions of inner circular layer compress and mix components in the lumen, outer longitudinal layer propels food by shortening the tube. Rhythmic contractions produce peristalsis
What controls peristalsis
enteric nervous system
Lumen of the esophagus looks like what?
Highly involuted and convoluted
Epithelial layer of the esophageal mucosa is made up of what kinds of cells
SSE Nonkeratinized
GALT located in what layer of esophagus
Mucosa
Upper third of the muscularis externa of the esophagus is all what type of muscle?
Skeletal muscle
Middle third of esophageal muscularis externa
mixed skeletal and smooth
Lower third of esophageal muscularis externa?
All smooth
Upper and lower esophageal sphincters made up of what type of muscle
smooth
Layers in the stomach wall
M/ S/ MP/S Mucosa Submucosa Muscularis External Serosa
Mucosa of the stomach has what type of epithelium>
Non-ciliated columnar
Four regions of the stomach
- Cardia
- Fundus
- Body
- Antrum
What is the overall function of the stomach
digestion…not absorption
Unique features of stomach epithelium?
Composed entirely of pale staining mucous cells called surface mucous cells.
What are gastric pits?
Mucosal surface is studded with small holes, called gastric pits, where the epithelium invaginates into the lamina propria.
What do surface mucous cells of the stomach epithelium produce
alkaline mucous to protect the stomach lining
What are the five cell types within gastric glands
- Mucous neck cells
- Chief Cells
- Parietal Cells
- Enteroendocrine cells
- Stem cells
MCPES
Chief cells found where
Deep part of gastric gland. Appear very basophilic.
What do chief cells secrete
Pepsinogen, the inactive form of pepsin
Parietal cells found where>
most numerous in the upper part of the gland
What do parietal cells secrete?
HCL and intrinsic factor
Parietal cells look like what
Pyramidal, red/pink on H&E
Cell division in the stomach occurs where?
Isthmus
Surface mucous cells live how long
3-5 days
What is the difference between a mammillated fold and a rugae?
Mamillated folds are small elevations of mucosa only.
Rugae elevations contain mucosa and submucosa
Three sections on Small bowel in order
duodenum, jejunum, ileum
What are the 3 modifications present in the Small intestine to increase surface area?
1) Plicae Circularis- permanent transverse folds of the mucosa, contains a core of submucosa, Increases surface area by three fold
2) Villi- increase surface area 10 fold
3) Microvilli- increase surface area 100 fold
Cell type in small intestine?
Epithelium is simple columnar and made up of 6 cell types. They are:
1) Enterocytes- primary absorptive cell, attached to neighboring cells by tight junctions, also secrete water and electroloytes
2) Goblet cells
3) Paneth Cells- found in the base of crypts, basal basophilia, intensely acidophilic granules. Secretes lysozyme, regulates gut bacteria
4) M cells: Overlie lymphatic nodules
5) enteroendocrine cells
6) Intermediate cells- stem cells
Lamina propria in the mucosa of the small intestine is heavily infiltrated with what?
GALT
Peyer’s patches best seen where?
Ileum
What the fuck is a peyer’s patch
an aggregation of lymph nodes in the gut (ileum mostly)
Brunner’s glands are what?
Glands that secrete alkaline mucous, found in the submucosa of the DUODENUM, They hypertrophy in peptic ulcer dz
Ileum distinguished by
Peyer’s Patches!
Easiest way to tell the small intestine from large?
Large has no villi, dawg
Large also has more goblet cells for better lubrication.
Function of the large intestines
absorption of water and electrolytes and elimination of solid waste.
What separates the large intestine from teh small
ileocecal valve
Epithelium in the Large intestine is basically the same as the small. It is —– —— in type but it has no —— cells
simple columnar, paneth cells
