Stomach Flashcards
Where is the stomach?
between the duodenum and oesophagus
Where is the stomach found in the abdominal regions?
epigastric, left hypochondrium
What is at the anterior/superior regions of the stomach?
lower ribs/ diaphragm
liver
What is at the posterior/inferior regions of the stomach?
diaphragm, spleen, left kidney, adrenal gland, pancreas
What does the pyloric sphincter do?
allows food to pass from the stomach to the small intestine -prevents partially digested food and digestive juices from reentering the stomach
What condition can affect the pyloric sphincter?
pyloric stenosis which prevents the stomach from emptying into the small intestine
What are the rugae?
folds of the organ which can be seen with the naked eye. They help increase surface area and allow for the folding and expansion of the organ.
What are the 3 muscles of the stomach
inner circular
outer longitudinal
an extra layer called the innermost oblique.
What substances does the stomach absorb and what is this due to?
aspirin and alcohol due to high vascularisation
What are the secretory cells of the stomach and what do they secret?
mucous cells - mucus
parietal (oxyntic) cells - HCL and intrinsic factor
chief (zymogenic) cells - pepsinogen, lipase
neuroendocrine cells (G cells) - gastrin, serotonin
What is the difference between the neck mucous cells and the surface mucous cells?
neck cells produce mucus that is a little more acidic
What is the intrinsic factor required for?
Vitamin B12 absorption in the ileum
What happens to pepsinogen?
becomes activated by HCL breaking it down to become pepsin which breaks proteins into smaller amino acids
What stimulates the production of HCL by parietal cells?
hormone gastrin released in the bloodstream by endocrine cells stimulates parietal cells to produce HCL
Describe parietal (oxyntic) cells in an H&E stain
large round or pyramid-shaped cells, highly acidophilic (very pink), central round nucleus
Describe chief (zymogenic) cells in an H&E stain
found in lower regions of the gastric glands, basophilic (very blue)
Where is carbonic anhydrase found?
red blood cells, parietal cells in gastric mucosa, pancreatic cells, liver and renal tubules
What reaction does carbonic anhydrase catalyse?
catalyses the reaction between water and carbon dioxide to produce carbonic acid (H2CO3), and dissociated products hydrogen and bicarbonate
Where are the stomach arteries derived from?
branches of the coeliac trunk
How is the stomach held in place?
lesser omentum - extends from the liver to the lesser curvature of the stomach and is also attached to the duodenum
greater omentum - runs from the greater curvature to the transverse colon
What is the coeliac trunk and what does it divide into?
The coeliac trunk is a short, wide vessel arising from the anterior aspect of the aorta.
It divides into three branches: the left gastric, the common hepatic and the splenic arteries.
What gastric veins drain directly into the portal vein?
the right and left gastric veins.
Describe how stomach acid HCL is produced
HCl is produced by the parietal cells of the stomach. To begin with, water (H2O) in the parietal and carbon dioxide (CO2) from blood combine within the parietal cell cytoplasm to produce carbonic acid (H2CO3), which is catalysed by carbonic anhydrase. Carbonic acid then spontaneously dissociates into a hydrogen ion (H+) and a bicarbonate ion (HCO3–).
The hydrogen ion that is formed is transported into the stomach lumen via the H+/K+ ATPase ion pump. This pump uses ATP as an energy source to exchange potassium ions in the parietal cells of the stomach with H+ ions.
The bicarbonate ion is transported out of the cell into the blood via a transporter protein called an anion exchanger which transports the bicarbonate ion out of the cell in exchange for a chloride ion (Cl–). This chloride ion is then transported into the stomach lumen via a chloride channel.
This results in both hydrogen and chloride ions being present within the stomach lumen. Their opposing charges lead to them associating with each other to form hydrochloric acid (HCl).
What are the arteries that supply the stomach?
Right gastric artery
Left gastric artery
Short gastric artery
Gastroduodenal artery
Right gastroepiploic (gastroomental) artery
Left gastroepiploic (gastroomental) artery
What is anastomosis?
a surgical connection between two structures
What is oesophageal varices?
The lower 1/3rd of the oesophagus drains towards the left gastric vein, which in turn goes to the portal vein.
In abnormal livers (alcholics, hepatitis), scar tissue builds up (cirrhosis) and blocks the portal vein therefore blood increases in the portal vein.
When pressure increases in the liver, this results in collateral circulation developing around the lower oesophagus. These can end up rupturing and can be fatal.
Oesophageal varices are abnormally enlarged veins in the oesophagus.
What are the types of weight loss surgeries and what are they?
1.Gastric band where a band is tightened around the stomach to decrease its size
2.Gastric bypass (where the top part of your stomach is joined to the small intestine
3.Sleeve gastrectomy where some of the stomach is removed.
Describe gastric bypass
the top part of the stomach is joined to the small intestine, decreasing the size of the stomach
the duodenum is reconnected as the bile from the liver and the pancreatic enzymes are still needed for digestion.
What are the main regions of the stomach?
cardia, fundus, body, pylorus
What are the divisions of the pylorus?
pyloric antrum, pyloric canal, pyloric sphincter
What are the borders of the stomach called?
greater, and lesser curvatures
What is the greater omentum and what is it’s function?
Attached to the greater curvature of the stomach and transverse colon. Made from 2 layers of peritoneum. Made from adipose tissue, lymphatics, blood vessels and nerves.
The function is fat storage and infection encasing.
What is the lesser omentum and what is its function?
Attached from the lesser curvature to the liver. Also made from 2 layers of peritoneum. adipose tissue, lymphatics, blood vessels and nerves.
The function is to attach stomach and duodenum to liver
Where does the arterial supply of the stomach come from?
coeliac trunk
What parasympathetic nerve innervates the stomach?
vagus 10
What is the semi-liquid substance composed of digested food and gastric juices called?
chyme
What is the epithelial lining of the stomach?
simple columnar epithelium with mucus protective layer with gastric pits that delve into gastric glands
What veins drain into the splenic vein then into the superior mesenteric vein?
short-gastric and left gastroepiploic (gastroomental) veins
What vein drains directly into the superior mesenteric vein?
right gastroepiploic (gastroomental) vein
Why is mucous important in the stomach?
provides alkaline to combat the strongly acidic environment that can cause ulcers if not neutralised
How is gastrin produced?
innervation of the parasympathetic vagus nerve results in acetylcholine, acting on receptors on parietal cells. The hormone gastrin is produced by endocrine cells in the pyloric antrum in response to rising gastric pH
What are the sympathetic nerves of the stomach?
T6-T9
