Digestive System II Flashcards
What are the 4 layers of the esophagus and GI tract?
- Mucosal Surface - faces lumen
- Submucosa
- Mascularies Externa - no less than 2 layers of musculature, usually smooth muscle
- Serosa/Advensitia - serosa free, adventitia - anchors to other structures
What tissue type is the adventitia made of?
DCT
What tissue type is the mucosa made of? What does it contain?
Epithelium
Lamina Propria
Muscularis Mucosae
What is tissue type is the submucosa made of? In some locations they may contain what two accessories?
DCT
In some locations may contain glands or lymphatic nodule
What two layers compose the Muscularies externa?
Inner circular layer
Outer longitudinal layer
What does the muscularis externa do?
Allows for peristalsis
Pushes the food down the GI tract
What tissue type is in the serosa? What is its function?
Mesothelial lining (simple squamous epithelium) Created slick surface
What are the three layers of the mucosa?
- Epithelial Lining
- Lamina Propria
- Muscularis mucosae
What are contianed in the lamina propria?
Glands
What is contained in the submucosa?
Submucosal nerve plexus / Meissner’s Nerve Plexus
What two locations contain a submucosa?
- Esophagus
2. Duodenum
What is contianed int he muscularis externa?
Myenteric Nerve Plexus
What are the purposes of the two layers in the muscularis externa?
Inner Layer - circular: compress digestive materials
Outer Layer - longitudinal: corkscrew movement to push digestive materials along
What is the function of the esophagus?
Delivers food from pharynx to stomach
What is an identifying feature of the esophagus? What is its purpose?
The shape of the lumen, without food it collapses
Allows it to expand and contract as needed
Is there little or high amounts of regeneration of the epithelium of the esophogus?
There is constant regeneration of the epithelium
Is the muscularis mucosae thin or thick in the esophogus? What does this aid in?
The longitudinal smooth muscle in the proximal esophagus is thick
Aids in swallowing
What does the submucosa of the esophogus contain?
Submucosal (Meissner’s) plexus
Esophageal glands proper
How does the musculares externa of the esophagus change as you move down it?
Proximal 1/3 is skeletal muscle
Middle 1/3 is a combination of skeletal and smooth
Lower 1/3 is smooth muscle
Does the esophagus have adventitia or serosa?
Converts from adventitia to serosa upon entering the abdominal cavity
What do you see at the esophagus-stomach junction?
Transitions from stratified squamous to simple columnar
See the presence of pits
Thickening of musculature
What is the function of sphincters in the esophagus-stomach junction?
Control movement from one region to the next
Does the stomach perform endocrine or exocrine functions?
Mixed exocrine-endocrine organ
How does the stomach act as an endocrine system?
Releases digestive enzymes
How does the stomach act as an exocrine system?
DNES (diffuse neuroendocrine system): enteroendocrine
Release of ghrelin signals hunger
Release of gastric amylase, pepsinogen from chyme
What are the 4 parts of digestion?
- Carbohydrates
- Proteins
- Triglycerides
- Forms Chyme
What are the 4 anatomical regions of the stomach?
- Cardia: small, runs continuously
- Fundus: below cardia
- Body: bulk
- Pylorus: right before duodenum
Does the body of the stomach exist according to histologists?
No, the body and the fundus are made of the same tissue
What are rugae? Where are they located? What is their function?
Rugae are places where the submucosa juts upwards creating permanent longitudinal folds
Found in the stomach
Allows the stomach to expand with eating
When are Rugae most promienet?
When the stomach is empty
Where is the cardiac region of the stomach?
Narrow circular band surrounding the esophageal orifice
What is the function of the cardiac glands? Where are they found? Are there many pariental cells?
Found in the cardiac region of the stomach
Produce mucus and lysozyme
Few parietal cells
What is the function of gastric pits? What type of cells are they lined with? Where are they located?
Gastric pits are filled with musin and make insoluble mucus that goes over the entire surface of the stomach so it doesn’t get eaten away
Lined with surface mucous cell - give it a clear appearance
Begin at esophagogastric junction
What is the location of gastric (fundic) glands?
Fundus Stomach (bulk)
What are the three portions of the gastric (fundic) glands?
- Isthmus
- Neck
- Fundus
What type of cells are found in the isthmus region of gastric (fundic) glands?
Stem cells
What type of cells are found in the neck region of gastric (fundic) glands? (2)
Parietal Cells
Mucous Neck Cells
What type of cells are found in the fundus region of gastric (fundic) glands? (2)
Chief Cells
Enteroendocrine cells
What is the function of the mucous neck cells in the neck region of gastric (fundic) glands?
Make soluble mucus to solubilize chyme
What is the function of the parietal cells int he neck segments of the gastric (fundic glands)? What do they look like?
Make HCl and Intrinsic Factor
Big, pink, rounded or pyramidal in shape