HUBS192 Lecture 21 - The Stomach and Pancreas Flashcards
what is the shape of the stomach?
J-shaped organ
what is the oesophageal hiatus?
break or hole (junction) in the oesophagus to allow the oesophagus to pass through the stomach
where is the stomach located?
located at the base of the oesophagus
what is the function of the lower oesophageal sphincter (LES)?
prevents reflux of food material back up into the oesophagus
how does the lower oesophageal sphincter allow the food bolus into the stomach?
relaxes to allow the food bolus to travel into the stomach and then contracts to prevent reflux
what are the 4 main parts/regions of the stomach?
1) cardia
2) fundus
3) body
4) pylorus (pyloric antrum)
what is cardia region of the stomach?
small region where the oesophagus opens up into the stomach
what is the fundus region of the stomach?
proximal region where the gastric glands are located and gases produced as a byproduct of digestion collect
what is the largest region of the stomach?
the body
what is the pylorus (pyloric antrum) region of the stomach?
antrum= cave like
pylorus = gate keeper
where the pyloric sphincters acts as a gate keeper by regulating the passage of luminal content from the stomach into the first part of the small intestine
what is the function of the pyloric sphincter?
regulates the process of gastric emptying
what does the lesser omentum attach to?
attaches the lesser curvature of the stomach to the liver
what does the greater omentum attach to?
attach to the greater curvature of the stomach and then folds back up to attach to the transverse colon
what does the greater omentum contain?
a significant number of clusters of immune cells
- important for isolating infections
- first line of bacterial infection of the peritoneal cavity
what are the modifications of the gut tube layers of the muscularis?
muscularis is modified for motility
what are the 3 layers of the stomach?
1) oblique (inner)
2) circular (middle)
3) longitudinal (outer)
where is the muscualris layer of the stomach thickest?
thickest in the distal region of the stomach (the pylorus) rather than the proximal region of the stomach (fundus)
why is the muscularis thickest in the distal region of the stomach (pylorus) than the proximal region of the stomach (fundus)?
because there needs to be more contractility in the distal region of the stomach to aid in the mechanical and chemical digestion
what are rugae?
temporary folds that allow for the expansion of the stomach (increase up to approx 1.5L)
-by flattening out
what are rugae important for?
important for storage function
- and the sphcinters
what are the components that make up the rugae?
folded core of submucosa with overlying mucosa
-this allows the flattening of the stomach
glands are permanent and only located in the mucosa
what are the 3 things the stomach requires to perform its functions?
1) acid and enzymes for digestion
2) mucous for protection
3) hormones for regulation (motility and secretion)
what are the 3 cells of gastric glands?
1) parietal cells
2) G cells
3) chief cells
what do parietal cells secrete?
secrete acid and intrinsic factor
what do G cells secrete?
secrete hormones into the blood (gastrin)
what do chief cells secrete?
secrete pepsinogen (an inactive precursor of pepsin) aka enzymes
what is abundant in chief cells?
- abundant in the rough endoplasmic reticulum
- significant amount of apical zymogen (enzyme) granules
- nucleus is in the basal layer
what is abundant in parietal cells?
- secrete HCI by pumping ions (H+)
- abundant in mitochondria
- central nucleus
- folded structure to increase surface area
what are the 2 ways to regulate stomach function?
1) endocrine control
2) neural control
what are the 2 ways that endocrine control regulates stomach function?
1) endocrine cells in the mucosa
2) gastrin and gherlin secreted into the bloodstream
what are the 2 ways that neural control regulates stomach function?
1) enteric nervous system (ENS) controls through local reflexes (primary control)
2) CNS modulates enteric nervous system (ENS) function through long neural reflexes
what is the relationship of the diameter between the stomach and the first region of the small intestine?
large difference in diameter between the stomach and the first region of the small in intestine
what is chyme?
the controlled release of digested material into the small intestine
what does acidic chyme require as it enters the small intestine?
1) further digestion (enzymes and bicarbonate)
- provided by the pancreas
2) protection from acidic chyme
- mucous: provided by glands in the submucosa of the duodenum
- neutralise acid
what is the shape of the pancreas in terms of its head and tail?
- head in C-shaped duodenum
- tail to spleen
what is the duct where the pancreas delivers secretions?
delivers from the duct to the lumen of the duodenum
what is the location of the pancreas?
posterior to the stomach (retroperitoneal)
what does the liver produce and where does it store this?
liver produces and stores and concentrates this in the gale bladder
where is the bile duct located?
bile duct meets pancreatic duct at the entrance to the hepatopancreatic ampulla
what controls the release of bile?
release controlled by hepatopancreatic sphincter
what projects into the duodenal lumen?
duodenal papilla projects into the duodenal lumen
what are the endocrine functions of the pancreas?
1) pancreatic islet alpha cells secrete glucagon
2) pancreatic islet beta cells secrete insulin
what are exocrine glands?
glands that secrete into the lumen of an organ
what are the 2 functions of the pancreas?
1) acinar cells secrete digestive enzymes
2) duct cells secrete bicarbonate
what is the structure of the pancreatic acinar cells?
-apical zymogen granules (transports enzymes towards the apical membrane to be exocytosed into the lumen)
what is the function of apical zymogen granules?
transports enzymes towards the apical membrane to be exocytosed into the lumen
what is the function of an pancreatic acinar cell?
to secrete enzymes
what structures allow storage in the stomach?
- sphincters
- rugae: distension (folded submucosa)
what does the stomach need for mechanical digestion?
- smooth muscle, additional oblique layer in the stomach
- sphincters
what does the stomach need for chemical digestion?
- secretion of strong chemicals (acids, enzymes)
- protective epithelium
