Esophagus and Stomach Flashcards
What is the mucosa made of generally?
surface epithelium lamina propria (loose CT) muscularis mucosae (smooth muscle)
If there is smooth muscle in the mucosa, how does it run?
longitudinally
What are the layers of the submucosa?
more dense CT
larger blood vessels
submucosal (Meissner) plexus
What is the function of the submucosal plexus within the submucosa?
influence mucosa
What are the layers of the muscularis externa?
myenteric plexus
typically smooth muscle
What is the typical fiber orientation in the muscularis externa?
inner circular and outer longitudinal layers (normal pattern)
Where is the myenteric plexus located within the muscularis externa?
between the circular and longitudinal muscle layer
What is the function of the myenteric plexus in the muscularis externa?
incfluence muscularis externa
What is serosa made of?
serous producing simple squamous spithelium and some CT
What is adventita made of?
connective tissue and some collagen and adipose
What is the function of the esophagus?
transfer bolus to stomach from the oropharynx
What are the parts of the mucosa of the esophagus?
surface epithelium, lamina propria, muscularis mucosa
What is the surface epithelium of the luminal wall of the esophagus made of?
stratified squamous, langerhans cells, antigen presenting cells with some phagocytosis possible
What is the lamina propria of the lumina wall of the esophagus made of?
loose areolar (irregular) CT and some esophageal cardiac glands
What is the function of the esophageal cardiac glands?
produce neutral mucus to protect esphageal epithelium
What is the location of the esophageal cardiac glands?
near the pharynx (first inch) near stomach (last inch)
Where were the esophageal cardiac glands first discovered?
near the stomach (last inch)
What is the muscularis mucosae of the mucosa of the luminal wall of the esophagus made of?
a discontinuous layer of longituidinal msucle, which is thinner distally (near pharynx) and thicker proximally (near stomach)
What is the submucosa of the of the mucosa of the luminal wall of the esophagus made of?
dense fibroelastic CT that contains esophageal glands (proper) scattered along the length of the esophagus
What is the function of the esophageal glands (proper)?
produce slightly acidic mucus to lubricate the movement of food
What are the muscle layers of the muscularis externa of the luminal wall of the esophagus?
normal pattern (inner circular and outer longitudinal) upper 1/3= all skeletal muscle middle 1/3= mixture of smooth and skeletal muscle lower 1/3= all smooth muscle
What part of the esophgus does the adventita/serosa of the luminal wall make up?
primarily adventita except for the last 1-2 inches, which are serosa
What are the two physiological sphincters of the esophagus?
pharyngoesophageal and gastroesophageal sphincter
Where is the pharyngoesophageal sphincter located?
between the oropharynx and esophagus
Where is the gastroesophageal sphincter located?
between the esophagus and stomach
Which sphincter is prone to problems from abrupt change?
gastroesophageal sphincter
What are the characteristics for physiological sphincters?
no thickening of circular muscle in muscularis externa
pressure gradient aids movement (muscle contractions and gravity help)
What are the functions of the stomach?
continue digestion of carbohydrates
storage
some nutrient breakdown (primarily chemical, little physical)
What is the primary function of the stomach?
storage
What are the layers of the luminal wall of the stomach?
mucosa, submucosa and muscularis externa
What is the surface epithelium of the mucosa of the luminal wall of the stomach made of?
simple columnar, surface mucous (surface lining) and regeneragive cells (bases of pits)
What is the function of the surface mucous of the surface epithelium of the mucosa of the luminal wall of the stomach?
to produce thick visible mucus for protection
secrete bicarbonate ions
What is the lamina propria of the mucosa of the luminal wall of the stomach made of?
loose, vascular CT present in small amounts between glands
What is the muscularis mucosae of the mucosa of the luminal wall of the stomach made of?
smooth muscle layer that is often arranged in three layers
inner circular, outer longitudinal and outermost circular/oblique
What are the characteristics of the submucosa of the luminal wall of the stomach?
it is highly vascular, this is also the location of arteriovenous anastomosis and it also has the submucosal (meissner’s) plexus
What is the function of the AVA of the submucosa of the luminal wall of the stomach?
to shut down activity and secretion FAST
What is the function of the submucosal plexus of the submucosa of the luminal wall of the stomach?
to influence the mucosa (secretion, blood flow, any limited muscle contraction
What are the 3 muscle layers possible in the muscularis externa of the mucosa of the lumina wall of the stomach?
especially between the cardiac region and greater curvature, all smooth muscle innermost oblique (sometimes) middle circular (well developed) outer longitudinal (thin)
What are the muscle patterns for the stomach (minus the cardiac region and greater curvature)?
normal pattern (inner circular and outer longitudinal)
What are the cell types in the cardiac region of the stomach?
surface mucous, some neck mucous and a few DNES and parietal cells
NO chief cells
Which part of the stomach is smallest and obtains much mucous?
cardiac region
What are the three regions of the gastric (zymogenic) gland?
isthmus, DNES and base cells
What does the isthmus do and what is its function?
its surface mucous produces thick visible mucus that traps bicarbonate ions to protect mucosa from auto-digestion and the rougher componenets of chyme
What are examples of DNES (enteroendocrine) cells?
type D, EC, and G
What does type D DNES cells do?
produces somatostatin
inhibits release of hormones by nearby DNES cells and HCL release
What does type EC DNES cells do?
produces serotonin and substance P
increases gut motility
What does Type G DNES cells do?
produces gastrin
stimulates HCL and pepsinogen secretion, gastric motility and regenerative cells in body of stomach
What do neck mucous cells do?
produce a soluble, slightly acidic mucus
to lubricate gastric contents
What type of cells are neck cells?
neck mucous cells, regenerative cells, parietal (oxyntic) cells and DNES cells
What do regenerative cells of the neck of the gastric pit do?
replace all cell types
What kind of cells are parietal (oxyntic) cells?
odd columnar with intracellular canaliculi
What do parietal (oxyntic) cells do?
produce very strong HCl, which is immediately buffered to 1-2 pH
also produce gastric intrinsic factor, which is necessary for Vitamin B12 absorption
What can chronic gastritis lead to? How?
pernicious anemia
the low number of parietal cells can lead to low amounts of intrinsic factor, which will decrease vitamin B12 absorption which is necessary for RBC maturation
What are the types of chief cells in the gastric pit?
chief (zymogenic) cells, parietal cells and DNES cells
What do chief (zymogenic) cells do?
produce primarily pepsinogen to break down proteins
also produces some gastric lipase to break down fats
What does the pyloric region of the stomach contain?
deeper pits, surface mucous, DNES, parietal cells, some neck mucous cells
What do the neck mucous cells within the pyloric region of the stomach do?
produce some lysozyme
How are the pits of the pyloric region different than the gastric pits?
the pyloric pits are very twisted and branched and also shorter
What is the pyloric sphincter?
an anatomical sphincter between the pylorus of the stomach and the duodenum
What are the characteristics of an anatomical sphincter?
well developed inner circular layer of muscle in the muscularis externa
inner circular layer in muscularis externa can be independently controlled
