Histology Of The Upper GI System (esophagus & Stomach)-1/6/16 Flashcards
What are the 3 components of Mucosa?
1) lining epithelium with mucosal and submucosal glands & ducts
2) underlying lamina propria with vascularized loose CT
3) thin layer of smooth muscle, the muscularis mucosae
What type of epithelium is the oral cavity, oropharynx, esophagus and anal canal?
What type of epithelium is the stomach, SI, LI, and rectum?
Non-keratinized stratified squamous
Simple columnar
This part of the mucosa increases contact area with food and propels and mixes food in GI tract
Muscularis mucosae
This layer consists of a dense irregular CT with large BVs, lymphatics, and nerves branching into the mucosa and muscularis.
Submucosa
What are folds of the stomach called?
Rugae-Increase surface area for absorption
Where do you find the Meissner plexus?
Where do you find the Auerbach (myenteric) plexus?
Submucosa
In the Muscularis between the circular and longitudinal layer
What are the 2 layers in the muscularis externa?
Circular layer and Longitudinal layer
____ is outside the peritoneal cavity, binds to the body wall, is loose CT and contains BVs and nerves
____ is within the peritoneal cavity, made of loose CT, simple squamous epithelium, contains BVs, nerves, and adipose tissue
Adventitia
Serosa
This division of the Extrinsic ANS decreases motility/secretions
This division of the Extrinsic ANS increases motility/secretions
Sympathetic
Parasympathetic
Which portion of the esophagus do you find thin, elastic fibers? Smooth muscle?
Upper esophagus-thin, elastic fibers
Lower esophagus-Smooth muscle fibers
Where do you find skeletal muscle in the muscularis externa of the esophagus?
Upper 1/3-Voluntary swallowing
Lower 2/3-Smooth muscle, under autonomic control and controls peristalsis
What is the epithelial transition from esophagus to stomach?
Non-keratinized stratified squamous –> Simple columnar
The ___ sphincter participates in initiation of swallowing
The ___ sphincter prevents gastric reflux
UES-anatomically defined, cricothyroid
LES-functionally defined, gastroesophageal sphincter
What can cause GERD?
Change in epithelium of esophagus to columnar (like stomach), chronic esophagitis/ulceration, dysphagia, fibrosis and/or esophageal strictures
____ is a condition in which an abnormal columnar epithelium replaces the stratified squamous that normally lines the distal esophagus. It is the most severe histologic consequence of chronic GERD and predisposes to development of adenocarcinoma of esophagus
Barrett’s esophagus
What are the 4 regions of the stomach?
Cardia, fundus, body, & pylorus
What is the function of the Orad area?
What is the function of the Caudad area?
Orad area and LES relax during swallowing
Involved in regulation of gastric emptying
____ glands are simple tubular and coiled at the lower end. These are lined by mucus-secreting cells and have a structure similar to the esophageal cardiac glands found in the mucosa of the esophagus.
Cardiac glands–> extend from pit or foveola down through mucosa and coil
____ cells are located at the opening of the gastric gland into the pit and produce mucins and glycoproteins with high MW. Produces a mucus blanket to trap HCO3- and neutralizes microenvironment adjacent to apical region of the surface of mucous cells to an alkaline pH
Mucous neck cells
____ cells predominate in the lower 1/3 of the gastric gland and secrete pepsinogen. These cells are NOT present in cardiac glands and are seldom found in the pyloric antrum
Chief
___ cells secrete HCl and IF and are numerous in the upper portion of the body of the gastric gland
Parietal
____ is caused by autoantibodies to H+,K+-dependent ATPase, a parietal cell ag., and IF. Destruction of parietal cells causes are reduction in HCl in the gastric juice (achlorhydria) and a lack of synthesis of IF.
The resulting B12 deficiency disrupts formation of RBCs in BM, leading to pernicious anemia
Autoimmune gastritis
The parasympathetic mediator ___ and the peptide ___ stimulate parietal cells to secrete HCl
Ach, Gastrin
Ach can also stimulate release of gastrin
Where does H pylori like to reside?
Gastric epithelium of the pyloric antrum
These cells produce peptide hormones and are also neuroendocrine mediators. They are members of Diffuse Neuroendocrine System (DNES). These cells regulate water, electrolyte metabolism, and enzyme secretion; regulate GI motility and mucosal growth; stimulate release of other peptide hormones
Gastroenteroendocrine cells
____ is released by cells in the duodenal glands of Lieberkuhn when the gastric contents enter the stomach. It stimulates pancreatic and duodenal (brunner’s glands) bicarb and fluid release to control gastric acid secretion (antacid effect) and regulate the pH of the duodenal contents.
Secretin
Secretin, along with ____, stimulates growth of exocrine pancreas. Secretin can also stimulate chief cells to secrete ___, and inhibit ___ release to reduce HCl secretion in the stomach.
CCK
Pepsinogen
Gastrin
____ is produced by G cells located in the pyloric antrum and its function is to stimulate the production of HCl by parietal cells. It can also activate CCK to stimulate gallbladder contraction
Gastrin
___ is produced in the duodenum and stimulates gallbladder contraction and relaxation of sphincter of Oddi when protein- and fat-rich chyme enters duodenum.
CCK
___ is produced in the duodenum and stimulate insulin release when glucose is detected in the SI
Glucose-dependent insulinotropic peptide (GIP)
___ is released cyclically (every 90 mins) during fasting from the upper SI and stimulate GI motility. A neural control mechanism regulates its release
Motilin
____ is produced in the fundus of the stomach and stimulates the secretion of GH. The levels of this peptide hormone increase during fasting triggering hunger by acting on hypothalamic feeding centers
Ghrelin
List the 4 layers of the GI tract
Mucosa (epithelium, lamina propria, muscularis mucosa)
Submucosa (connective tissue; contains glands, BV’s, nerves)
Muscularis externa (smooth muscle; 2-3 layers)
Adventitia (for esophagus, most of duodenum) OR Serosa (rest of GI) –> This layer is made up of connective tissue to support and bind organ to others
