10 Digestive System II--Esophagus to Stomach Flashcards
Does the early embryo undergo median folding (head and tail) or horizontal folding (lateral body fold)?
BOTH- and in doing so the digestive tract is formed [along with thoracic and abdominal cavities, heart, pleura, peritoneal membrane etc.]
What is included in the foregut?
esophagus to proximal duodenum
What is included in the midgut?
distal duodenum to proximal colon [also includes accessory organs of digestion]
What is included in the hind gut?
distal colon to the anal canal [I think generally the hind gut includes the last 1/3 of the transverse colon on down]
What is the epithelial layer in the esophagus?
non-keratinized stratified squamous
What is found in the lamina propria of the esophagus?
- esophageal cardiac glands [mucous-only in most distal region near stomach]
- lymphoid aggregates
What is found in the esophagus submucosa?
esophageal glands [mucous secreting for bolus passage]
What 2 types of muscle are generally found throughout the muscular is extern of the esophagus?
inner circular and outer longitudinal
Is the upper 1/3 of the esophagus muscle smooth muscle?
NO–skeletal muscle [last 1/3 is smooth and the middle is mixed]
What type of tissue makes up the esophageal adventitia/ serosa?
loose irregular connective tissue adventitia and then gets covered by peritoneum near hiatus and becomes serosa
Is the stomach only a chemical digester?
No mechanical as well
What are the 4 distinct regions of the stomach?
cardia, fundus, body, pylorus
What type of epithelium is in the stomach? what do they produce?
simple columnar- cells produce neutral mucous
Besides epithelial cells, what else exists in the epithelial layer of the stomach?
gastric pits and gastric glands-
T-F– the gastric pits and glands do not extend to the lamina propria?
false
What is different about the muscular is extern in the stomach?
It has an innermost oblique layer
What muscle layer forms the pyloric sphincter?
middle circular layer [think of the direction of the fibers for the job]
T-F– the outer layer of the stomach is covered by mesothelium?
True- peritonized within the abdomen
What gland is most common in the stomach?
principal gastric gland
What cell type makes up the gastric pit?
surface mucous cell [same as columnar epithelial and secrete a neutral mucous]
What gastric gland cell secretes mucous to protect stomach from self digestion?
neck mucous cell
What gastric gland cell is mainly located in the upper portion of the gland, are largely rounded with a central nucleus?
parietal (oxyntic) cell
What gastric gland cell stains very eosinophilic?
parietal cell
What does the parietal cell secrete?
HCl and intrinsic factor
Why are many mitochondria needed in parietal cells?
ATP needed to drive process of H and Cl locations for HCl production
Is the proton pump in the parietal cell an anti porter or symporter? with what molecule?
anti—-K+
Where does the HCl formation actually take place?
in the canaliculus
What is a glycoprotein required for uptake of vitamin B12 in the gut?
intrinsic factor
What is found in the stomach of many people with gastric ulcers?
H. pylori- helical shape and flagellum allow it to burrow into mucous and stay protected–
What can impairment of intrinsic factor lead to?
pernicious anemia—B12 uptake is down which is needed during the process of hematopoiesis
What gastric gland cell is located in the lower portion and stains basophilic? what do they secrete?
chief cell- pepsinogen and rennin/chymosin
What activated pepsinogen?
HCl in the stomach lumen clips off those extra 44 amino acids that blocked the active site
What does chymosin do?
curdle and coagulate milk to maximize time in stomach
T-F–rennin is the preferred method to make cheese?
True
What gastric gland cells are part of the diffuse neuroendocrine system?
enteroendocrine cell-release a variety of hormones into blood vessels
Where are the G cells located in the stomach? what hormone? causes what?
- body and pylorus
- gastrin
- increase parietal cell/chief cell secretion & contraction of m. externa
Where are the D cells located in the stomach? what hormone? causes what?
- pylorus
- somatostatin [triggered by increased acid]
- targets G cells to inhibit their release
Where is the ghrelin cell located in the stomach? what hormone? causes what?
- body
- ghrelin [low glucose response]
- targets hypothalamus to increase appetite
Are there goblet cells in the stomach?
No
What are the key features of the cardiac glands?
- in cardia
- short gastric pits
- long coiled gastric glands
- primarily mucous cells
What are key features of principal glands?
- in fundus and body
- the gastric pits are short
- long and branched gastric glands
- full complements of stomach cells
What do neuroendocrine cells secrete in the fundus and body of the stomach?
ghrelin and gastrin
What are the key characteristics of pyloric glands?
- in the pylorus
- the gastric pits are long
- glands are short and coiled
- primarily mucous secreting cells
What do neuroendocrine cells secrete in the pylorus of the stomach?
gastrin and somatostatin
What glands have short gastric pits?
principal and cardiac
What happens in Barrett’s esophagus?
metaplasia–> normal stratified squamous of esophagus changes to columnar epithelium [chronic exposure to stomach acids and enzymes during reflux esophagitis]
