Embryology of the GI Tract/Stomach Flashcards
What are the three independent parts of the alimentary tract in early embryological development?
Foregut, midgut, hindgut
The foregut forms what structures?
Distal esophagus, stomach, and part of the duodenum
Where does the foregut end?
Second part of the duodenum at the entrance of the bile duct
Where does the midgut begin and end?
Begins are the entrance of the bile duct into the second part of the duodenum and ends with the right 2/3 of the transverse colon
Where does the hindgut begin and end?
Begins with the left 1/3 of the transverse colon and ends in the upper part of the anal canal
Why are the three embryological divisions of the GI tract important?
The adult derivatives of each have a unified blood supply and autonomic nerve supply
All of the blood supply to the foregut, midgut, and hindgut come from what place?
Abdominal aorta
What is the blood supply to the foregut?
Branches of the celiac trunk
What is the blood supply to the midgut?
Branches of the superior mesenteric artery
What is the blood supply to the hindgut?
Branches of the inferior mesenteric artery
What is the sympathetic innervation of both the foregut and midgut?
Greater splanchnic nerves (T5-T9) and lesser splanchnic nerves (T10-T11)
What is the sympathetic innervation of the hindgut?
Lumbar splanchnic nerves (L1-L2)
What is the parasympathetic innervation of both the foregut and midgut?
Vagus nerve
What is the parasympathetic innervation of the hindgut?
Pelvic splanchnic nerves (S2-S4)
What is the sympathetic effect on the GI tract?
Decreased motility and tone and contraction of sphincters
What is the parasympathetic effect on the GI tract?
Increased motility and tone and relaxation of sphincters
What are the four major layers of the gut wall?
Mucosa, submucosa, muscularis externa, serosa/adventitia
What layer of the gut wall is a mucous membrane (important for absorption) that contains the muscular mucosae with is a thin layer of smooth muscle?
Mucosa
Which layer of the gut wall is very vascular?
Submucosa
Which layer of the gut wall is a loose connective tissue layer containing blood vessels and lymphatics?
Submucosa
What layer of the gut wall is a thick layer of smooth muscle responsible for peristalsis?
Muscularis externa
Peristalsis moves in which direction?
Distally
The muscularis external consists of what two layers?
Inner circular layer and outer longitudinal layer
What is another name for visceral peritoneum of the gut wall?
Serosa
What is the name for the connective tissue coat covering retroperitoneal organs?
Adventitia
What is the name of the semi-independent regional system of nerves responsible for the gut?
Enteric nervous system
Where is the submucosal plexus located?
Within the submucosa near its border with the muscularis externa
What do the postganglionic fibers of the submucosal plexus supply?
Muscularis mucosae and mucus secreting glands
Where is the myenteric plexus located?
Between the circular and longitudinal layers of muscularis externa
What do the postganglionic fibers of the myenteric plexus supply?
Both layers of the muscularis externa
What action is the myenteric plexus responsible for?
Stimulation of peristalsis
What is the shape of the stomach when empty?
J-shaped
What is the capacity of the stomach?
2-3 liters
What are examples of foreign things the stomach can absorb?
Some drugs and alcohol
The stomach lies in what regions of the abdomen?
Left hypochondriac, epigastric, and umbilical regions
What is the function of the stomach?
Storing and mixing food with gastric secretions, therefore converting it into chyme
What part of the stomach is where the esophagus joins the stomach (surrounds the cardial orifice)?
Cardia
What part of the stomach is above the cardia?
Fundus
What part of the stomach is between the fundus and pyloric part?
Body
What part of the stomach is the most distal portion and is adjacent to the duodenum?
Pyloric part
What is the narrow distal part of the pyloric part of the stomach?
Pyloric canal
What is the notch of the stomach called that is between the esophagus and fundus?
Cardial notch
What is the notch of the stomach called that is between the body and pyloric part?
Angular incisure
Where is the cardial orifice located?
Between the esophagus and fundus
Where is the pyloric orifice located?
Between the stomach and duodenum
What is the wide proximal part of the pyloric part of the stomach called?
Pyloric antrum
What is the distal termination of the pyloric part of the stomach?
Pylorus
What two things does the pylorus contain?
Pyloric orifice and pyloric sphincter
What is the pyloric muscle?
Circular muscle layer which surrounds the pyloric orifice
What does “pylorus” mean?
Gatekeeper
Why does the mucous membrane of the stomach have gastric folds (rugae)?
Increased surface area and allows for stomach expansion
What is congenital hypertrophic pyloric stenosis?
A tumor-like increase in the size of the pyloric sphincter which reduces the size of the pyloric canal
Congenital hypertrophic pyloric stenosis is more common among what gender?
Males
What does congenital hypertrophic pyloric stenosis result in?
Projectile vomiting
What is the treatment for congenital hypertrophic pyloric stenosis?
Surgical intervention early in infancy
What is pylorospasm?
Spasmodic contraction of pyloric sphincter
What is the effect of pylorospasm?
Food does not pass easily from the stomach to the duodenum & the stomach becomes overly full leading to vomiting (possibly projectile)
Pylorospasm can sometimes be present in what population?
Infants
Subluxations of what area could play a role in pylorospasm?
T5-T9
What is a gastric ulcer?
A crater-like depression in the mucosa of the stomach
What are the causes of a gastric ulcer?
Excess acid secretion (often related to stress) or inadequate mucus barrier (usually related to erosion due to the presence of bacteria)
What is the mucous secreted by the stomach like?
Sticky, viscous, and alkaline
Subluxation of what sympathetic area could play a role in gastric ulcers?
T5-T9 (affecting the secretion of gastric acid from parietal cells)
Where does the stomach lie in reference to the pancreas?
Anterior
Where does the stomach lie in reference to the lesser sac?
Anterior
Where does the stomach lie in reference to the diaphragm?
Posterior
Where does the stomach lie in reference to the left lobe of the liver?
Posterior
Where does the stomach lie in reference to the anterior abdominal wall?
Posterior
What is the blood supply to the stomach?
Branches of the celiac trunk
What is the sympathetic innervation of the celiac plexus to the stomach?
Greater splanchnic nerves (T5-T9)
What is the parasympathetic innervation of the celiac plexus to the stomach?
Vagus nerve
Where does the celiac trunk lie?
Immediately below the aortic hiatus of the diaphragm as the first unpaired branch from the abdominal aorta
What is the smallest branch of the celiac trunk that runs along the lesser curvature within the lesser omentum to anastomose with its right branch??
Left gastric artery
What are the two types of branches of the left gastric artery?
Esophageal and gastric branches
What is the largest branch of the celiac trunk that runs posterior to the stomach along the superior border of the pancreas to terminate in the spleen?
Splenic artery
What are the branches of the splenic artery?
Pancreatic branches, short gastric arteries, left gastro-omental artery, common hepatic artery
What branch of the splenic artery goes to the fundus of the stomach?
Short gastric arteries
What branch of the splenic artery runs to the right along the greater curvature of the stomach within the greater omentum?
Left gastro-omental artery
What branch of the splenic artery runs to the right along the superior border of the pancreas?
Common hepatic artery
When does the common hepatic artery become the hepatic artery proper?
After giving off the gastroduodenal artery
What branch of the common hepatic artery descends behind the first part of the duodenum?
Gastroduodenal artery
What branch of the gastroduodendal artery goes to the superior aspect of the duodenum?
Supraduodenal artery
What branch of the gastroduodendal artery runs to the left along the greater curvature of the stomach along the pyloric part within the greater omentum?
Right gastro-omental artery
What branch of the gastroduodenal artery passes between the duodenum and head of the pancreas?
Superior pancreaticoduodenal artery
What branch of the hepatic artery proper runs along the lesser curvature of the stomach within the lesser omentum to anastomose with its left?
Right gastric artery
Which branch of the hepatic artery proper goes to the left lobe of the liver?
Left hepatic artery
What branch of the hepatic artery proper goes to the right lobe of the liver?
Right hepatic artery
What does the cystic artery supply?
Gall bladder