GI II Flashcards
What are the 4 layers of the GI tube?
Mucosa
Submucosa
Muscularis
Adventitia/serosa
What are the components of the mucosa of the GI tube?
Epithelium resting on BL
Lamina propria
Muscularis mucosae
What does the lamina propria of the GI tube contain?
CT
Glands
Vessel
Lymph
What is the structure and function of the muscularis mucosae (muscular layer of the mucosa)?
a. Two layers of smooth muscle (inner circular and outer longitudinal)
b. Contraction wrinkles the mucosa thereby increasing surface area. This facilitates absorption of nutrients and secretion.
Most of the epithelium of the GI tube is of what type? Where is it different?
Simple columnar
Different in the proximal esophagus and anal canal have stratifed squamous
Where in the GI tube are glands present in the submucosa?
Esophagus and duodenum
What forms the submucosal layer of the GI tube? (3)
Dense CT with blood/lymph and Submucosal (Meissner’s) plexus
What are the two layers to the muscularis externa? Contraction of these muscles result in what?
inner circular and outer longitudinal.
Peristalsis
Can the muscularis externa have three muscle layers?
Yes–in the stomach
What is the outermost layer of the GI tube?
Serosa
What are the two nerve plexuses of the GI tube, and where are they found?
Submucosal (meissner’s)
Myenteric (Auerbach’s)– located in muscularis externa
What does the submucosal (Meissner’s) plexus contain?
Parasympathetic and sympathetic postganglionic fibers
What is the function of the submucosal (Meissner’s plexus)?
Regulates glandular activity, blood flow, muscularis mucosae, and is sensory (mechano- and chemo-)
What does the myenteric (Auerbach’s) plexus contain?
Parasympathetic and sympathetic postganglionic
What is the function of the myenteric plexus?
Controls peristalsis
What is the epithelial layer of the esophagus?
Stratified squamous, nonkeratinized epithelium
Where in the esophagus are the cardiac esophageal glands found? What is their function?
In the lamina propria.
Secrete mucus for lubrication
What type of glands are found in the submucosa of the esophagus?
Seromucous
Where is the muscularis mucosea developed in the esophagus?
Distally
What percent of the upper esophagus is controlled by skeletal muscle?
5%
What percent of the esophagus is smooth muscle?
> 50%
Where do you find adventitia surrounding that esophagus? Serosa?
Thoracic esophagus = adventitia
Abdominal esophagus = serosa
What is the line that separates the esophagus’s stratified epi and the stomach’s simple columnar?
Z line
What type of stain is used to highlight the goblet cells of Barrett’s esophagus? What do color do goblet cells and mucus cells stain?
PAS/Alcian blue
Goblet = blue Mucus = reddish/purple
What type of epithelial change occurs in Barrett’s esophagus?
Stratified squamous to columnar with goblet cells
What third of the esophagus is most likely to arbor an adenocarcinoma?
Distal third
How is cancer graded?
By how far a CA penetrates through the GI tube wall
Why does CA in the esophagus usually spread in a superior/inferior direction?
d/t orientation of the lymph flow
If CA spreads in the (blank) of the esophagus’s lymph nodes, it will spread upward.
upper 2/3rds
What is achalasia?
Damage to certain neurons in the myenteric plexus causes constriction of the LES, causing a bird beak appearance in the distal esophagus
What are the four regions of the stomach?
- Cardia
- fundus
- body
- pylorus
What are the rugae of the stomach?
Longitudinal folds in the undistended stomach formed by the mucosa and submucosa
What epithelial type comprises the suface epithelium of the stomach?
Simple columnar, mucus cells
What are gastric pits?
Invaginations of the stomach surface epithelium into the lamina propria
Are there many lymphatics in the stomach?
No
What are the tubular profiles of the epithelium of the stomach, that are in the lamina propria?
Glands
What are the three gland regions?
Isthmus
Neck
Fundus
What are the three layers of the muscularis externa of the stomach?
- Inner oblique layer (only present in some areas)
- Middle circular layer
- outer longitudinal layer
Where is the Middle circular layer of smooth muscle of the stomach thickened?
At the pylorus
What are the glands of the stomach?
Cardiac glands
Gastric glands (most diverse)
Pyloric glands
What is the isthmus of gastric glands? What is its function/cell type here?
The open segment of the gland. This is the stem cell niche
What is the area of gastric glands that is just below the isthmus? What is the main type of cell here?
The neck.
Parietal cells
What do parietal cells secrete?
HCl and intrinsic factor
What is the main cell type in the fundus of a gastric gland? What do they secrete?
Chief cells
Pepsinogen
What is the deepest component of a gastric gland?
The fundus
What do the surface epithelial cells of the stomach secrete?
Mucus
What do the entreoednocrine cells in the fundus of gastric glands do?
Secrete hormone
What is the major secretion of the cardiac glands of the stomach?
Mucus
What is characteristic of the cardiac glands of the stomach?
SHORT gastric pits, LONG glands in the lamina propria
Few other cell types besides mucus cells
What is characteristic of the pyloric glands of the stomach?
LONG gastric pits with SHORT glands, filled with mostly mucus secreting cells
What is the alkaline tide?
Bicarbonate that is excreted from the chief cells into the blood stream and carried to the stomach epithelial cells for secretion into the mucus
True or false: the goblet cells of the stomach epithelium secrete protective mucus
False-the epithelial cell do, there are no goblet cells
What is the difference between a stomach ulcer and erosion?
If the erosion of the stomach goes through to the submucosa. Otherwise it is erosion
True or false; prostaglanins play a role in protecting the stomach lining
True
Why is lots of cell renewal needed in the stomach epithelium?
To regenerate against the low pH
What is the gastroduodenal junction?
pyloric sphincter is a thickening of the muscularis externa, chiefly its inner circular layer.
What are the pilcae circulares?
permanent circular folds of submucosa and mucosa in the intestines
What are the intestinal villi?
highly vascular processes of mucosa
What are the microvilli?
Villi on the villi
What happens in gluten enteropathy? (4 signature features)
a. Enterocytes are disarrayed
b. Villus atrophy
c. Crypt (intestinal gland) hyperplasia
d. Inflammation of the lamina propria
What is zollinger-Ellison syndrome?
Hyperplasia of the GI tube d/t a gastrin-secreting tumor
Tumor may arise in the duodenum, pancreas, or peripancreatic soft tissue
What are the three apexes of the gastrinoma triangle?
- Junction of cystic and common hepatic ducts
- Junction of pancreatic head and neck
- Junction of part 2 and 3 of duodenum
The pyloric sphinicter of the stomach is a thickening of what layer of the GI tube?
Circular layer of the Muscularis
What are the three structural modification of the small intestines?
Plicar circularis
Villi
Microvilli
The plicae circularis is an extension of what layer of the GI tube?
The mucosa and submucosa
What forms the core of the villus of the intestines?
Lamina propria
What specialization do the epithelium of the villi of the intestine have?
Goblet cells
