2. Histology of the Gut
The jejunum contains what kind of mucosa?
Jejunum- standard villi, NO glands
Change in structure from Pylorus to Duodenum:
Lymph- stomach Villi and Brunner's glands- Dueodenum
What is the general layout of the gut by layers?
Mucosa Muscularis Mucosa Submucosa 2 layers of muscle (inner-circular, outer-longitudanal) Autonomic Ganglia Serosa or Adventitia
Tissue from the esophagus showing various layers
Mucosa (epithelium, lamina propria, muscularis mucosa), Submucosa, Muscle (2x... inner circular, outer longnitudinal), adventitia
What kind of cells are Paneth cells? What do they contain?
Paneth cells- granular cells with lysozyme
What kind of cells are Paneth cells? What do they contain?
Paneth cells- granular cells with lysozyme.... immune "testing" function
what is the function of the external muscle layer of the epithelium?
The two muscle layers work together to produce peristalsis and move food along the oesophagus to the stomach.
recto-anal junction
change from columnar epithelium to squamous epithelium for shredding purposes and discontinuous longitudinal muscle becomes continuous.
What are the the muscle layer in the colon?
continuous circular muscle layer. Taenia coli - discontinuous longitudinal muscle layer
What are the glands of the stomach and their functions?
1) Parietal (Oxnitic)- secrete HCL and intrinsic factor 2) Chief cells- secrete pepsinogen, rennin, lipase
What are the glands of the stomach and their functions?
1) Parietal (Oxnitic)- secrete HCL and intrinsic factor 2) Chief cells- secrete pepsinogen, rennin, lipase for digestion 3) Mucous cells= secrete mucous for ease of movement through the GI tract
What kind of cells in the distal anal canal?
Distal- stratified squamous mucosal
Duodenum contains ______ glands
Duodenum- submucosal/Brunner's glands
Where do you find Brunner's glands? What do they do?
Duodenum... secrete an alkaline fluid composed of mucin, which exerts a physiologic anti-acid function by coating the duodenal epithelium, therefore protecting it from the acid chyme of the stomach.
What is the general layout of the gut by layers?
Epithelium (mucosa) Lamina propria (mucosa) Muscularis Mucosa (mucosa Submucosa + neural plexus 2 layers of muscle (inner-circular, outer-longitudanal) + neural plexus between layers Adventitia
How is the appendix recognized?
Flat on the surface, straight glands, and giant lymph nodes.
How is the appendix recognized?
Flat on the surface, straight glands, and giant lymph nodes. Crypts are similar to those in the large intestine, but the longitudinal layer of muscular is externa is continuous (teniae coli in LI)
The mucosa of the esophagus is what kind of tissue?
Flat squamous- stratified squamous non-kertinized
What is the defining characteristic of the colon?
Flat surface (no villi) Straight glands lots of goblet cells!
Mucosa of the stomach is what?
Flat, tortuous glands
The mucosa of the colon is what?
Flat- straight glands
What cells can you see in the small bowel?
In the crypts of lieberkun Absorptive cell Goblet cell Paneth cell
What cells can you see in the small intestine? (Duodenum, Jejenum, Ileum)
In the crypts of lieberkun Absorptive cell Goblet cell Paneth cell
what is the function of absorptive cells in the colon?
Absorption of water from the gut lumen.
How many muscle layers does this stomach have?
3= oblique muscle layer, circular muscle layer, longitudinal muscle layer
functional significance of the villi in the small intestiner
Brush border is composed of microvilli, which further increase surface area for absorption
What type of epithelium are present in the duodenum?
Columnar absorptive epithelium.
What type of epithelium is present in the stomach, and how does this relate to function?
Columnar secretory epithelium. Secreting mucous and enzymes to prepare food for absorption.
What kind of glands are in the Pyloric (Antral) mucosa?
Mucous cells (mucous and lysozyme) and Neuroendocrine cells (Gastrin- primary site)
What kind of glands are in the Pyloric (Antral) mucosa?
Mucous cells (mucous and lysozyme)= prevent self digestion Neuroendocrine cells (Gastrin- primary site)
What kind of glands in the esophagous?
Mucous, pepsinogen, lysozyme
How do you recognize Goblet cells?
Pale because of mucous
What do parietal cells look like? Chief cells?
Parietal- slightly more pale Chief cells- darker, granulated
What is the defining characteristic of the ileum?
Peyers patches, and numerous lymph follicles
What kind of cells in the proximal part of the anal canal?
Simple columnar Lots of nerve endings **********- distinguish between solid, liquid, gas.
What kind of cells in the proximal part of the anal canal?
Simple columnar Lots of nerve endings- distinguish between solid, liquid, gas.
When is the first time you see goblet cells in the gut?
Small bowel- first part of duodenum They secrete alkaline mucous that neutralizes stomach acid. Also produce urogastrone that inhibits HCL production.
What's inside the villus core of the small intestines?
Smooth muscle, lacteals, and plasma cells. 250 square meters
what type of epithelium lines the esophagus?
Stratified squamous epithelium.
what is the gastro-esophageal junction?
Sudden transition from squamous to columnar epithelium
In the stomach, there are more folds.
Surface lining cells Mucuous neck cells Parietal cells (HCL) Chief Cells (Zymogenic) Enteroendocrine cells
What cells are found in the stomach?
Surface lining cells Mucuous neck cells Parietal cells (HCL) Chief Cells (Zymogenic) Enteroendocrine cells
Function of acid secretion by parietal cells
The acid aids in the breakdown of food by chemically disrupting bonds. This results in a liquid known as chyme, of broken down food and gut secretions.
What is the function of the glands with the oesophageal wall?
These glands secrete mucous to lubricate the passage of food= mucosa glands
Function of mucous secreted by mucous cells
Thick mucous lines the wall of the stomach, preventing self-digestion.
how does the type of epithelium in the esophagus relate to its function?
This type of epithelium protects against friction from passing food by shedding the layers closest to the lumen.
What kind of muscle in the esophagus muscularis externa?
Upper 1/3- Skeletal Middle 1/3-Mixed Lower 1/3- smooth
How does the colon differ from the small intestine?
Villi are absent, crypts are straighter and more densely packed with goblet cells. Brush border is absent. Longitudinal muscle is mostly discontinuous, arranged as three strips along the colon. However, the longitudinal muscle returns to a continuous layer in the rectum.
The epithelium of the small intestine is what?
Villous
The mucosa of the small intestine is what?
Villous
The jejunum contains what kind of mucosa?
standard villi, NO glands
Duodenum contains ______ glands
submucosal/Brunner's