The Stomach and Duodenum Flashcards
What are the four areas of the stomach?
Cardia
Fundus
Body
Antrum
Where does the fundus lie?
Proximally, under the left diaphragm
What does the antrum serve as?
A reservoir where food can be retained and broken up before being spelled into the small intestine
What are the three layers of the stomach smooth muscle wall?
Outer longitudinal
Inner circular
Innermost oblique
Which part of the stomach has thick folds or rugae?
The greater curvature
Which cells are in the upper two thirds of the stomach?
Parietal cell
Chief cells
What do parietal cells secrete?
HCl
Intrinsic factor
What do chief cells secrete?
Pepsinogen
Do HCl, intrinsic factor, gastrin and pepsinogen inhibit or stimulate acid production?
Stimulate
Which cells are present in the antral mucosa of the stomach?
G and D cells
What do G cells secrete?
Gastrin
What do D cells secrete?
Somatostatin
How do somatostatin, VIP and GIP affect acid sectretion?
Inhibits it
What is the function of the mucosal barrier?
To protect gastric epithelium from damage.
What is the function of prostaglandins?
Stimulate the production of mucus
Which substances inhibit prostaglandins to inhibit the production of mucus?
Aspirin
NSAIDs
Where are Brunner’s glands located?
Duodenum
What is the function of Brunner’s glands?
They secrete alkaline mucous to help neutralise acid secretion along with pancreatic and biliary secretions
Which nerve supplies the stomach?
The nerve of Laterjet
What are the three phases of acid secretion?
Cephalic
Gastric
Intestinal
What is the cephalic phase of acid secretion?
The thought, signs and smell of food stimulate the vagus, producing ACh
What is the gastric phase of acid secretion?
Distension by food activates mechanoreceptors and directly stimulates secretory cells and gastrin release
What is the intestinal phase of acid secretion?
The passage of food into the duodenum inhibits gastric secretion
How does histamine increase acid secretion?
Stimulates the Gs (gastrin stimulating) protein via the H2 receptors and acts via cAMP to increase acid secretion
How does prostaglandin E2 inhibit acid secretion?
Activates the Gi (gastrin inhibiting) protein to inhibit acid secretion
How does ACh increase acid secretion?
Acts via the vagus M3 receptors and also via the enterochromaffin cells to increase acid secretion
How does gastrin increase acid secretion?
Acts via the cholecystokinin B gastrin receptor, increasing intracellular free calcium.
Also acts via the enterochromaffic-like cells, stimulating histamine to increase acid secretion
What is gastritis?
The term used to indicate inflammation associated with mucosal injury
What is gastropathy?
The term used to describe epithelial cell damage and regeneration without inflammation
What are the causes of gastritis?
H. pylori (commonest) Autoimmune gastritis Viruses (CMV, HSV) Duodeno-gastric reflux Specific causes e.g. Crohn's
What can chronic inflammation of the gastric mucosa cause?
Gastric intestinal metaplasia, a pre-cursor to gastric cancer
Where does autoimmune gastritis affect, and what does this lead to?
Affects the fundus and body.
This leads to atrophic gastritis and loss of parietal cells
What cause the clinical syndrome of pernicious anaemia in autoimmune gastritis?
Rhydria and intrinsic factor deficiency
What is gastropathy usually caused by?
Irritants (drugs, NSAIDs, alcohol)
Bile reflux
Chronic congestion
When can acute erosive or heaemorrhagic gastropathy be seen?
After severe stress (stress ulcers)
Secondary to burns, trauma, shock or renal failure
In portal hypertension (portal gastropathy)
