Histology of the small and large intestines Flashcards
What is the principal location for digestion of food and absorption of digestive products?
Duodenum, jejunum, ileum
What is the black arrow and the bracket?
Arrow: microvilli
Bracket: plica circularis
What are intestinal villi?
- Mucosal folds that project into the lumen and cover surface of the small intestine. They are covered with a simple collumnar epi of enterocytes and goblet cells with a core of loose CT
Describe the 4 layers of the intestine
- Mucosa: simple columnar with tubular intestinal glands, includes the lamina propria and muscularis mucosae
- Submucosa: dense irregular CT, including neurovasculature, lymphatics, glads may be there
- Muscularis: inner circular and outer longitudinal layers
- Seosa: loose CT covered by visceral peritoneum
What controls the motility of the SI and LI?
ANS
slide 136
Label
- V: intestinal villi
- M: microfold cells
- C: crypt of Lieberkun
What is this and what is its function?
Paneth cell: Large eosinophilic pyramidal shaped cell at base of the intestinal glands
- functions in innate immunity by secreting antimicrobial substances
- Regulate normal bacterial flora
Stem cells can be found near them
What is the function of intestinal stem cells?
- Repopulate epithelial lining, daughter ccells move out of the crypts and differentiate into goblet cells enterocytes and enteroendocrine cells
What is the function of M cells?
- Epithelial cells specialized for transepithelial transport of particles and microorganisms
- Found in ileal mucosa on top of peyer patches
- Apical surface expresses receptors that bind gram negative bacteria and specific macromolecules
- cells get internalized and transferred to immune cells functioning as highly specialized antigen transporting cells
Enteroendocrine cells?
slide 140
Describe the mucosa and submucosa layers of this.
- Duodenum- has bruners glands
- Mucosa: simple columnar with scattered goblet cells
- Submucosa: duodenal glands: tubuloacinar mucous glands producing alkalkine secretion
- Neutralizes acidic chyme
Describe the mucosa and submucosal layer of this, and what are the deep purple staining circles?
- Ileum
- Mucosa:
- simple columnar with scattered goblet cells
- Vili shorter than jejunum
- Peyers patches
- Paneth cells at base of intestinal glands
- No submucosal glands
Peyers patches
What is this describe mucosa and submucosa
- Jejunum
- Mucosa:
- simple oclumnar epi with scattered goblet cells
- Long finger like villi, villus core has well developed lacteal
- Tubular intestinal glands
- Lymphoid nodues in lamina propria
- Submucosa: no glands
What is this?
Duodenum
What is this
Ileum
What is the Pyloris?
- Part of the stomach, it has a thick wall due to presence of pyloric sphincter muscle
- Pyloric glands are found at the base of each gastric pit
What is this, and describe it.
Gastroduodenal Junction
- can see bruners glands in the duodenum on the right
- can see pyloric sphincter muscle on left
Function of the large intestine?
- Absorbs water sodium vitamins and minerals
- Can uptake sedatives, anesthetics and steroids as well
- Openings of tubular intestinal glands are hallmark of mucosa
- Many goblet cells
- NO intestinal villi
What is this, describe the first three layers.
- Large Intestine
- Mucosa:
- glandular simiple columnar epi, colonocytes, goblet cells, stem cells nd enteroendocrine cells
- Lam ina propria nad mucsularis mucosae are present and GALT is extensive
- Submucosa: dense irregular CT and vascularized
- Muscularis:
- inner layer typical
- Outer layer reorganized into Taeniae coli forming haustra of LI
- Serosa covers the intraperitoneal portions while retroperitoneal has adventitia
What is this?
Large Intestine glands consitsitng of simple columnar epi with goblet cells- hallmark of LI
What is this and what are the layers
LI
Mucosa
Submucosa
ME
What is this
- Goblet cells at cross section in the LI
- Bottom is longitudinal section of a gland in LI showing goblet cells and colonocytes
What is Hirschprung’s disease, what mutation causes this?
- Aganglionosis in the distal colon
- Mutations in the RET gene cause failure of neural crest cells to migrate and develop both plexuses of the bowel segment
How does Hirschprung’s disease present? How do you diagnose? How do you treat?
- Constipation
- Poor feeding
- Progressive abdominal distension
Delayed BM <48 hrs after brith, rectal biopsy, barium enema
Surgical removal of the affected segment
Describe the Rectum proper.
- typical mucosa with tu;bular intestinal glands and transverse rectal folds
Describe the anal canal
- Inferior to the rectum proper
- Contains anal colums with mucosal folds
- Anal sinuses within the columns
- Anal glands extend into submucosa and muscularis externa
- Circumanal glands- large apocrine glands surrounding anal orifice
What is this
Anal Canal
- Colorectal zone (CRZ): simple columnar epithelium identical to rectum
- Anal transitional zone (ATZ): simple columnar epithelium transitioning to stratified squamous epithelium of perianal skin
- Squamous zone (SQZ): stratified squamous epithelium continuous with perineal skin lower 1/3
duodenal villi with microvili
what is this
jejunum
What is this and what is black line?
LI and Taniae coli
