5. Esophagus/Stomach Histo Flashcards
The muscosa differs the most from region to region so it is important to look at this when trying to identify GI areas. What are the four layer of the tract from lumen to superficial?
mucosa
submucosa
muscularis externa
serosa (if has peritoneum)/adventitia (if no peritoneum)
The mucosal layer has 3 components: simple columnar epithelium, lamina propria, and a thin layer of smooth muscle; muscularis mucosae. What is within the lamina propria? (4)
lymphatic nodules
lymphocytes
plasma cells
macrophages
What is the function of the smooth muscle in the mucosal layer, the muscularis mucosae?
controls mobility of the mucosa/mucosal glands
What layer of the GI tract consists of dense irregular CT with NV/lymphatics as well as glands (in esophagus and duodenum)
submucosal layer
The muscularis externa assists in the movement of food. There are two layers of smooth muscle with NV bundles residing between layers. What are the two layers of smooth muscle and how do they constrict?
Inner circular layer: contraction constricts lumen
Outer longitudinal layer: contraction shortens tube
What layer is it when the digestive tube is suspended by a mesentery/peritoneal fold covered in mesothelium?
Serosa layer
There is extrinsic (para/sympathetic) and intrinsic (ENS) innervation in the GI. What is the parasympathetic innervation to the GI? (2)
Vagus nerve until splenic flexure
Pelvic splanchnic from splenic flexure on (presynaptic)
the ganglion on postsynaptic fibers are intramural
Sympathetic innervation to the GI includes branches from the greater, lesser, least and lumbar splanchnics. What is the synapse and postsynaptic?
Synapse in prevertebral ganglia (celiac, Superior mesenteric, IM, aorticorenal)
Postsynaptic nerves travel to organs via plexuses
What are the two plexuses of sensory and motor neurons linked by interneurons and where can they be found?
Submucosal plexus of meissner (submucosa)
Myenteric plexus of Auerbach (muscularis externa in between inner circular and outer longitudinal layers)
What are the main functions of the submucosal plexus of meissner and the myenteric plexus of auerbach?
Submucosal: controls secretions of glands
Auerbach in muscularis externa: controls peristaltic contractions and movements of muscularis mucosae
The preganglionic acons of the parasympathetic increase motility while the postganglionic acons of sympathetics do what?
DECREASE motility
The esophagus has serosa or adventitia?
Both; Thoracic esophagus is adventitia, inferior to diaphragm is serosa
Mucosal and submucosal glands produce a thin layer of mucus to lubricate the epithelium. What is each of the glands?
Cardiac esophageal glands in the lamina propria near the cardia of the stomach
Submucosal glands in the submucosa
The mucosa of the esophagus is nonkeratinized stratified squamous epithelium, with number folds. What is only present in the lower segment?
muscularis mucosae d/t increase in cardiac glands
The submucosa of the esophagus has dense ireg CT with blood vessels called submucosal venous plexuses. What occurs when there is an increase in pressure here?
Can cause esophageal varices which are dilations of the veins
What is the hallmark of the muscularis layer of the esophagus? (3)
upper third: skeletal muscle
Middle third: skeletal and smooth muscle
lower third: smooth muscle
What is the epithelial change from the esophagus to the stomach at the gastroesophageal junction?
it goes from nonkeratinized stratified squamous to simple columnar with pits and glands
There is a UES and a LES in the esophagus. GERD or gastroesophageal reflux disease causes inflammation, ulceration and dysphagia (hard to swallow). What is a sign of GERD/Barrett’s esophagus?
when the nonkeratinized stratified squamous epithelium in the transition zone from E to stomach becomes columnar mucus-secreting/glandular!
The orad area is the fundus and upper part of the body of the stomach which relaxes during swallowing. What is the caudad area of the stomach?
lower portion of the body and pyloric antrum which helps with regulation of gastric emptying
Rugae are longitudinal folds of the gastric mucosa and submucosa, whose purpose is?
to increase friction in the stomach and assist in breaking down food
The mucosa of the stomach has simple columnar epithelium with a lamina propria containing glands (gastric, cardiac, pyloric) depending on the location in the stomach. What does the muscularis mucosae do?
facilitates the release of gastric gland secretions
What is different about the muscularis externa in the stomach? **Hallmark
There are three layers of smooth muscle, olique, circular then longitudinal
The circular muscle layer thickens in the pyloric region forming?
the pyloric sphincter
Fundic/Gastric glands are located everywhere except where pyloric and cardiac glands are. They are simple branches tubular glands which extend from gastric pits to muscularis mucosae. What are the 3 regions?
Isthmus: between gastric pit and gland
Neck: narrow, llong
Fundus: short and wide at base
