Lecture 21: The Stomach and Pancreas Flashcards
What shape is the oesophagus?
J-shaped
Where is the stomach located?
At the base of the oesophagus
What does the oesophagus pass through to get to the stomach?
Diaphragm
What is the passage that the oesophagus takes through the diaphragm called?
Oesophageal hiatus
Where is the lower oesophageal sphincter located?
At the base of the oesophagus and start of the stomach
What does the lower oesophageal sphincter do?
Prevent reflux
What 4 main part make up the stomach?
- Cardia
- Fundus
- Body
- Pylorus (pyloric antrum)
Where is the greater curvature of the stomach?
Lateral side of the stomach
Where is the lesser curvature of the stomach?
Medial side of the stomach
What is omentum?
A double layer of peritoneum that connects one organ to another
What does the lesser omentum connect?
The stomach to the liver
What does the greater omentum connect?
Stomach to transverse colon
What makes up the muscularis of the stomach?
3
- Oblique
- Circular
- Longitudinal
What is the muscularis modified for?
Motility
Where is the muscularis thicker in the stomach?
In the distal regions of the stomach when compared to the proximal end
What composes the pyloric part of the stomach?
4
- Pyloric antrum
- Pyloric canal
- Pyloric orifice
- Pyloric sphincter
What are rugae?
Temporary folds in the stomach that allow for expansion
What are rugae important for?
Storage function
How are rugae composed?
A folded core of submucosa with overlying mucosa
What is the mucosa of our gut tube comprised of?
Simple columnar epithelium
What does in-folding do to the mucosa in our gut?
Increases surface area for secretion
Are gastric glands temporary or permanent?
Permanent
What do we need acid and enzymes for?
Digestion
What do we need mucous for?
Protection
What do we need hormones for?
Regulation
On the surface of the epithelium and the neck of the glands what do goblet cells do?
Secret mucous for protection
What do parietal cells of gastric glands do?
Secret acid and intrinsic factor
What do G cells of gastric glands do?
Secrete hormones (gastrin)
What do chief cells of gastric glands do?
Secrete pepsinogen (an inactive precursor of pepsin)
What are 3 features of chief cells?
- Abundant rough endoplasmic reticulum
- Apical zymogen granules (contain enzymes)
- Basal nucleus
What are 4 features of parietal cells?
- Pump hydrogen ions
- Abundant mitochondria
- Central nucleus
- Folded structure to increase surface area
Why are chief cells specialised in their structure?
To produce protein
How are parietal cells specialised in their structure?
Lots of mitochondria provide the energy to pump ions against their gradient
What endocrine control is involved with the stomach?
Endocrine cells in the mucosa secreting gastrin/ghrelin into the blood stream
What neural control is involved with the stomach?
The enteric nervous system - local reflexes (primary control)
What does the CNS modulate around the stomach?
Enteric nervous system function, long neural reflexes
What controls the release of digested material (chyme) from the stomach to the small intestine?
Pyloric sphincter
Once acidic chyme enters the small intestine what is required?
(2)
- Further digestion (enzymes)
- Protection of the small intestine from acidic chyme, using mucous and neutralising acid
Where is the mucous produced for the small intestine receiving chyme?
Glands in the submucosa of the duodenum
What provides the enzymes and bicarbonate for the small intestine receiving chyme?
Pancreas
Where is the head of the pancreas?
In the C-shaped duodenum
Where does the tail of the pancreas face towards?
The spleen
Where does the pancreatic duct go?
Into the duodenal lumen
Where is the pancreas as a whole located?
Retroperitoneal
Where does the bile duct meet the pancreatic duct?
At the entrance to the hepatopancreatic ampulla
Where does the duodenal papilla project?
Into the duodenal lumen
What is the release of substance from the pancreas controlled by?
Hepatopancreatic sphincter
What cells are involved in exocrine function of the pancreas?
(2)
- Acinar cells
- Duct cells
What do Acinar cells secret?
Digestive enzymes
What do Duct cells secret?
Bicarbonate
What are the structural features of pancreatic acinar cells?
3
- Apical zymogen granules
- Basal nucleus
- Abundant rough ER
