Stomach Flashcards
Location of abdominal cavity
between diaphragm and pelvic inlet (separated from thorax but not from pelvis - digestive function)
Why are the organs in the abdominal cavity not separated, unlike the heart and lungs in the thorax?
All organs in abdominal cavity work together for digestion
Why is there no solid division between the abdomen and pelvis?
to form a continuous space between the abdominal and pelvic cavities, allowing organs to interact and move.
Function of pelvis
structural support for lower abdominal organs (part of intestine, bladder) and site of attachment for muscles and ligaments to help stabilise and protect organs.
What components make up the abdominal wall?
Multi-layered musculoaponeurotic wall and adipose tissue
What is aponeuroses?
connective tissue that hold the muscle layers together in the abdomen.
Definition of musculoaponeurotic
musculo - muscular
aponeurosis - connective tissue
Term used to describe an abnormally swollen abdomen
distended abdomen
How is the abdomen divided?
9 areas - name related to bones and vertebra . Or into 4 quadrants - UR, UL, LL, LR
Where in the abdomen is the stomach found?
epigastric and left hypochondrium region
Side effects of distended abdomen
limited mobility, stomach paralysis, bloating, pain
Which structures are found anterior and superior to the stomach?
Liver, lower ribs, diaphragm
Which structures are posterior and inferior to the stomach?
Diaphragm (extends toward back of stomach), spleen, L kidney, adrenal gland, pancreas
What is the advantage of the lack of separation/boundaries in the abdominal cavity?
Organs can move and be displaced e.g. when the stomach expands during ingestion
4 sections of the stomach
cardia, fundus, body, pylorus
What structure controls the release of food into the stomach?
Lower oesophageal / cardiac sphincter - physiological due to angle
Which structure controls the movement of chyme into the duodenum?
Pyloric sphincter - allows maximum absorption of nutrients in small intestine
Which part of the stomach fills with gas and gives a bloating sensation?
fundus
Which side of the stomach has the greater curvature?
More lateral side (left)
Which side of the stomach has the lesser curvature?
More medial side (right)
Omenta definition
fused peritoneal folds connecting the stomach and duodenum with other abdominal organs
What is the greater omentum?
Largest of the two omenta - apron-like structure that extends from the greater curvature of the stomach to the transverse colon.
What is the name of the outer connective tissue in the stomach?
Serosa
Histological layers of the GIT
epithelium, lamina propria (mucous glands) and muscularis mucosae make up the mucosa. Submucosa is found beneath containing blood vessels, lymphatics, nerves, CT. Muscularis propria (CILO). Serosa/ Adventitia
Layers of muscle in muscularis propria in the stomach
oblique inner layer, circular middle layer, longitudinal outer layer.
Function of 3 layered muscle in muscularis propria in stomach
aids mixing and churning of food
Name of the gastric folds lining the inner surface of the stomach
Rugae
Function of rugae
Allow stomach to expand when bolus enters
Functions of the stomach
Retention of food in lumen if tract has slowed down. Mixing of gastric juice into chyme. Chemical (HCl) and mechanical functions. Absorption (limited - alcohol, aspirin)
Why are there regional variations in the composition of cells in the stomach?
Different sections (cardia, fundus, body, pylorus) have slightly different functions
Which cells are found in the stomach?
Mucus secreting cells (surface mucous cells), parietal (oxyntic) cells, gastric/endocrine cells, chief cells
Function of mucous secreting / surface mucous cells
Secrete an alkaline mucus as surface protection to prevent the stomach digesting itself.
Where are mucous secreting cells found?
Luminal surface of stomach and in gastric pits
Function of parietal (oxyntic) cells
Synthesise and secrete HCl and intrinsic factor (B12 absorption)
Function of chief cells
synthesise and secrete pepsinogen (inactive pepsin. Activated and converted to pepsin by HCl)
How is pepsin activated?
Pepsinogen is converted by pepsin by the presence of HCl which is released by parietal (oxyntic) cells
Function of endocrine/gastric cells
synthesise and secrete gastrin which stimulates HCl production by parietal (oxyntic) cells
Which cells are found in gastric glands?
Mucous neck cells, chief cells, parietal (oxyntic) cells, endocrine/G cells
What is the name of the membrane that wraps around organs?
Visceral peritoneum
How to differentiate between parietal (oxyntic) cells and chief cells using H&E stain
Parietal cells are more pink whereas chief cells are darker and blue in colour (pepsinogen production). Parietal cells have a round nucleus and are arranged in irregular layers.
Location of chief cells
in lower regions of the gastric glands in the stomach
Where are endocrine/gastric cells found?
At the bottom of the gastric glands
Mechanism for the release of HCl into the stomach lumen from parietal cells
- CO2 diffuses from the capillaries into parietal cells
- CO2 reacts with H2O to produce H2CO3 (catalysed by carbonic anhydrase).
- Carbonic acid dissociated to produce H+ ions and HCO3- ions
- The H+ moves into the stomach lumen via a H+/K+ pump which requires ATP
- HCO3- diffuses from the parietal cell into capillaries
- To balance the ions, Cl- diffuses from the capillaries into the parietal cell and then into the stomach lumen. (chloride shift)
Which artery contains the celiac trunk?
Abdominal aorta
Which arteries branch from the abdominal aorta at the celiac trunk?
Splenic artery, left gastric artery, hepatic artery
Which artery does the right gastric artery branch off?
Hepatic artery
Which arteries supply the lesser curvature of the stomach?
Left and right gastric artery (anastomose)
Which arteries supply the greater curvature of the stomach?
Short gastric arteries (upper part and fundus), left gastroepiploic artery, right gastroepiploic artery (L+R anastomose)
Which arteries branch from the splenic artery?
Short gastric arteries and left gastroepiploic artery
Which arteries branch from the hepatic artery?
Right gastric artery and gastroduodenal artery
What structures are supplied by the splenic artery?
Fundus and spleen
Which veins drain the lesser curvature?
Left and right gastric veins
Which veins drain the greater curvature?
Left and right gastroepiploic veins, short gastric veins
Where does the portal vein travel to from the stomach?
Liver
Which veins merge to form the splenic vein?
Short gastric veins and left gastroepiploic vein
Which veins join the superior mesenteric vein?
Splenic vein and right gastroepiploic vein
At what point does the superior mesenteric vein become the portal vein?
When the superior mesenteric vein combines with the splenic vein
Which veins join the portal vein?
Right gastric vein and left gastric vein.
How is the upper 2/3 of the oesophagus drained?
Into oesophageal veins which drain into the azygos vein and then into the superior vena cava
How is the lower 1/3 of the oesophagus drained?
Into the left gastric vein which drains into the portal vein to the liver, exiting into the inferior vena cava
What are oesophageal varices?
Abnormally dilated veins in the oesophagus
Cause of oesophageal varices
Cirrhosis in the liver or thrombosis in the portal vein can increase portal pressure. Portal hypertension means that portal pressure is greater than inferior vena cava pressure. Blood is redirected to bypass this high pressure system which creates a collateral circulation around the stomach, oesophagus and rectum.
Danger of oesophageal varices
Bulbus veins are susceptible to rupture which could be fatal.
Different forms of stomach surgery for weight loss
gastric band, sleeve gastrectomy, gastric by-pass
What does a laparoscopic adjustable gastric band surgery involve?
Flexible band placed around upper stomach near LOS to create a small pouch
What does a gastric by-pass involve?
A pouch is created in the upper stomach which is connected directly to the small intestine (usually jejunum) to bypass the body of the stomach. This reduces stomach capacity
Why is the duodenum reconnected to the jejunum in gastric by-pass?
Duodenum contains bile from the liver and pancreatic enzymes which are needed to aid digestion.
What is a sleeve gastrectomy?
~80% of the stomach along the greater curvature is removed to leave a sleeve-shaped stomach
