7- Histology of Esophagus & Stomach Flashcards
What are the four layers of the GI tract, from lumen to superficial?
Mucosa
Submucosa
Muscularis Externa
Serosa/Adventitia
***Serosa is covered by peritoneum, while Adventitia is retroperitoneal
In the GI tract, the ________ differs considerably from region to region. It reflects the functional activity.
Mucosa
The mucosal layer has three components, which are…
Lining Epithelium
Lamina Propria
Muscularis Mucosae
This layer of the mucosa consists of vascularized loose CT. It contains LNs, lymphocytes, plasma cells, and macrophages.
Lamina Propria
This layer of the mucosa consists of a thin layer of smooth muscle and controls the mobility of mucosa/mucosal glands.
Muscularis Mucosae
This layer of the GI tract consists of dense irregular CT with neurovasculature and lymphatics. Glands may be present (esophagus and duodenum).
Submucosal
This layer of the GI tract consists of two layers of smooth muscle, an inner circular layer and outer longitudinal layer.
Muscularis Externa
In the Muscularis Externa, contraction of the ________ layer constricts the lumen and contraction of the ________ layer shortens the tube.
Circular
Longitudinal
What resides between the layers of the Muscularis Externa (circular and longitudinal layers)?
Neurovascular Plexuses
When the digestive tube is suspended by a mesentery/peritoneal fold, the adventitia is covered by mesothelium forming the ________ layer.
Serosa
***Those without mesothelium have an adventitia!
T/F. Organs may have an adventitia and/or serosa, depending on location.
True
This type of mucosa is protective, and can be found in the oral cavity, pharynx, and anal canal.
Nonkeratinized Stratified Squamous
This type of mucosa is secretory. It is packed with glands and found in the stomach.
Simple Columnar Epithelium
This type of mucosa is absorptive. It is arranged as villi with crypts, and glands may be present (in small intestine).
Simple Columnar Epithelium
This type of mucosa is absorptive/protective. It is arranged into closely packed, glands (large intestine). Has extensive goblet cells.
Simple Columnar Epithelium
There are two plexuses of sensory and motor neurons, linked by interneurons, that provide intrinsic (enteric) innervation. What are these plexuses?
Submucosal Plexus of Meissner
Myenteric Plexus of Auerbach
This nerve plexus is between the inner circular and outer longitudinal layers of muscularis externa.
Myenteric Plexus of Auerbach
Responsive to local stimuli and input from ANS regulate and control what actions of the GI tract?
1) Peristaltic contractions of muscularis externa and movements of muscularis mucosae.
2) Secretory activities of the mucosal and submucosal glands.
__________ axons of the parasympathetics increase motility, while __________ axons of the sympathetics decrease motility.
Preganglionic
Postganglionic
This is a fibromuscular tube that conveys food from the oropharynx to the stomach.
Esophagus
Does the esophagus contain adventitia or serosa?
Both
Thoracic esophagus = Adventitia
Inferior to diaphragm = Serosa
Mucosal and submucosal glands produce a thin layer of mucus to lubricate the epithelium. ________ ________ ________ reside in the lamina propria of terminal esophagus, and _______ _______ consist of small lobules with mucous and serous cell types, drained by a single duct.
Cardiac Esophageal Glands
Submucosal Glands
What type of epithelium is the Mucosa of the Esophagus composed of?
Nonkeratinized Stratified Squamous
This layer of the esophagus overlies a lamina propria and has numerous folds.
Mucosa
***Muscularis Mucosae only present in lower segment!
This layer of the esophagus is a network of collagen and elastic fibers. There are many small blood vessels.
Submucosa
In the Submucosa of the esophagus, the ________ ________ ________ drain into both the systemic and portal venous system. Increased pressure can cause ________ ________, which are dilation of the submucosal venous sinuses.
Submucosal Venous Plexuses
Esophageal Varices
This layer of the esophagus has an inner circular and outer longitudinal layer that have segment-dependent variations.
Muscularis
Describe the parts of the Muscularis in the esophagus, and what type of muscle they’re composed of.
Upper third = Skeletal muscle (striated)
Middle third = Skeletal and Smooth muscle
Lower third = Smooth muscle
This esophageal sphincter is anatomical and helps with the swallowing reflex.
Upper Esophageal Sphincter (UES)
This esophageal disorder causes chronic inflammation, ulceration, and difficulty in swallowing (dysphagia) due to reflux of gastric contents.
GERD (Gastroesophageal Reflux Disease)
If GERD is chronic, nonkeratinized stratified squamous epithelium in transition zone becomes columnar mucus-secreting/glandular. This is called…
Barrett’s Esophagus (Metaplasia)
The Gastroesophageal Junction is the epithelial transition from the esophagus to the stomach. What types of epithelium are involved?
Esophagus = Nonkeratinized stratified squamous —- Stomach = Simple columnar
***Epithelium in the stomach is glandular with pits and glands.
What are the 4 regions of the stomach?
Cardia
Fundus
Body
Pyloric Antrum
Based on motility characteristics, this area of the stomach contains the fundus and upper part of the body. Relaxes during swallowing.
Orad
Based on motility characteristics, this area of the stomach contains the lower portion of the body and the antrum. Participates in the regulation of gastric emptying.
Caudad
Gastric mucosal folds, called ________, are covered by gastric pits. A gastric mucosal barrier protects the mucosal surface.
Rugae
This layer of the stomach consists of simple columnar epithelium. It has the lamina propria and contains cardiac, gastric, and pyloric glands.
Mucosa
In the Mucosa of the stomach, what type of fibers predominate?
Reticular
Collagen
In the stomach, ________ _______ facilitates release of gastric gland secretions.
Muscularis Mucosae
This layer of the stomach is composed of dense irregular CT with collagen and elastic fibers. It contains arterioles, venous plexuses, lymphatics, and Meissner’s Plexus.
Submucosa
This layer of the stomach contains three layers of smooth muscle, including oblique, circular, and longitudinal.
Muscularis/Muscularis Externa
In the Muscularis Externa layer of the stomach, the circular muscle layer thickens in the pyloric region forming the…
Pyloric Sphincter
This layer of the stomach consists of loose CT and blood vessels.
Serosa
What type of glands are Fundic (Gastric) Glands?
Simple, Branched, Tubular Glands
T/F. Fundic (Gastric) Glands extend from the bottom of gastric pits to the muscularis mucosae.
True
This is the invagination of the mucosal surface that leads to the gastric gland.
Gastric Pit
This is the narrow region between the gastric pit and the gastric gland.
Isthmus/Neck
This is what the gastric pits lead to, consisting of a shorter and wider base.
Gastric Gland
These cells line the lumen and gastric pits.
Surface Mucous Cells
These cells are located in the neck, in singles and/or clusters. They have round nuclei and apical secretory granules.
Mucous Neck Cells
The mucous cells in the stomach create a mucous layer, containing 95% water and 5% _______. This forms an insoluble gel that attaches to the surface of gastric mucosa. There is a thick coating that neutralizes the microenvironment to an alkaline _______.
Mucin
pH
These cells are predominately in the inferior regions of the gastric glands. Hallmarks include abundant RER and apical secretory (zymogen) granules.
Chief Cells
In Chief Cells, _________ is the proenzyme stored in the secretory granules. This is released (rapidly and stimulated by feeding) and converted to ________ by the acidic environment. This is a proteolytic enzyme that digests most proteins.
Pepsinogen
Pepsin
Chief Cells also produce _______ _______, which digests many lipids.
Gastric Lipase
These cells predominate near the neck and upper segment of the gastric gland. Hallmarks are that they are large cells, usually round or pyramidal-shaped. Have one (sometimes two) central round nucleus and cytoplasm is intensely eosinophilic due to increased mitochondria.
Parietal Cells
Parietal Cells produces ________ ________ (of gastric juice) and ________ ________, a glycoprotein that binds to Vitamin B12.
Hydrochloric Acid
Intrinsic Factor
Active Parietal Cells have a deep invagination of the apical plasma membrane, called an _________ _________. This creates large surface area produced by thousands of microvilli.
Intracellular Canaliculus
These are scattered epithelial cells in gastric mucosa with endocrine/paracrine functions. They secrete a range of products that are physiologically critical for digestive function.
Enteroendocrine Cells
These glands are in the narrow region of the stomach (the cardia) that surrounds the esophageal orifice. They are tubular, coiled, and somewhat branched and the opening is continuous with the gastric pits.
Cardiac Glands
Cardiac Glands are lined with ________-secreting cells (similar to those in esophagus).
Mucus
The hallmark of these glands are that they appear circular and oblique in sections.
Cardiac Glands
These are branched, coiled, tubular glands between the fundus and pylorus. They empty into pits that occupy half of mucosa. They are lined by mucus-secreting cells (resemble surface mucous cells).
Pyloric Glands
These glands have occasional enteroendocrine cells and parietal cells. Lymphoid nodules can be seen in the lamina propria (GALT).
Pyloric Glands
