lecture 21 - the stomach & pancreas Flashcards
How does the esophagus pass through the diaphragm and into the stomach?
Via the oesophageal hiatus
What feature of the oesophagus prevents reflux from the stomach?
The lower oesophageal sphincter (LES)
How does a bolus of food move through the oesophagus into the stomach?
Via peristalsis - a motility pattern - down the muscular oesophagus
What are the 4 main parts of the stomach?
Cardia, fundus, body, pylorus
What is the entry point of the stomach?
The cardia
What is the top of the stomach?
The fundus
What is the largest part of the stomach, making up the mid section?
The body
What is the bottom/exit part of the stomach?
The pylorus
what is the function of the pyloric antrum?
Connects the pylorus to the body of the stomach
What is the top of the small intestine where the contents of the stomach passes into?
The duodenum
What are the 2 omenta of the stomach?
Less and Greater omentum
What does the lesser omentum of the stomach connect?
Stomach to liver
What does the greater omentum of the stomach connect?
stomach to transverse colon
What are the 2 curvatures of the stomach called?
The greater and lesser curvature
How is the muscularis of the stomach adapted?
Modified for motility to promote mechanical digestion. Therefore, it has 3 layers rather than the usual 2
What are the 3 layers of the muscularis in the stomach?
oblique (inner), circular (middle), longitudinal (outer)
What part of the stomach has the thickest muscle?
The distal/bottom part to help move food through the stomach
What is the name for the temporary folds on the internal surface of the stomach?
Rugae
What is the function of the rugae of the stomach?
Temporary folds that allow for the expansion of the stomach for storage
What is the structrue of a single stomach rugae?
Folded core of submucosa with overlying mucosa
What do the gastric glands of the stomach secrete for digestion?
Acid & enzymes
What do the gastric glands of the stomach secrete for protection?
Mucous
What do the gastric glands of the stomach secrete for regulation?
hormones
What are the 4 types of cells that make up gastric glands/pits?
Mucous epithelial cells (gastric pit) parietal cells, G cells, chief cells (gastric gland)
What is a gastric pit?
A duct that lies at the surface above gastric glands and secretes mucous via mucous epithelial cells
What are the 3 cell types of gastric glands?
parietal cells, G cells, chief cells
What do parietal cells secrete?
Acid & intrinsic factor
What do G cells secrete?
hormones (gastrin)
What do chief cells secrete?
Enzymes, such as pepsinogen
What is pepsinogen?
Active precursor of pepsin, secreted by chief cells within gastric glands
How do parietal cells produce acid?
They pump protons (H+) against their concentration gradient out of the cell, using energy
What are the features of parietal cells that reflect their function?
Abundant mitochondria to power ion pumping, and large surface area. Central nucleus as no granules taking up space at the apical aspect
What are the features of chief cells that reflect their function?
Abundant rough ER for protein/enzyme processing, apical zymogen granules containing enzymes. Nucleus pushed to base of cell by full apical aspect
What are the 2 mechanisms of stomach regulation?
Endocrine and neural control
How does the stomach use the endocrine system for regulation of function?
Endocrine cells in the mucosa secrete the hormones gastrin and ghrelin into the bloodstream
What are the 2 key hormones for endocrine regulation of the stomach?
Gastrin and ghrelin
Where are the endocrine cells of the stomach found?
In the mucosa
How does the stomach use the neural system for regulation of function?
The enteric nervous system (ENS) provides primary control and local reflexes, and this modulated by long neural reflexes from the CNS
What is chyme?
Partially digested material, including acidic gastric acid and enzymes, that moves from the stomach into the duodenum
What physically controls the release of chyme into the small intestine (duodenum)?
The pyloric sphincter (PS)
What do the glands of the duodenum secrete?
Mucous, to protect the epithelium from the acidity of the chyme coming from the stomach
Where do digestive enzymes and bicarbonate in the duodenum come from?
The pancreas
What is the duodenal papilla?
The duct where fluid from the pancreatic and bile ducts pass into the lumen of the duodenum of the small intestine
Where do the pancreatic and bile duct meet?
At the entrance of the hepato-pancreatic ampulla
How is the release of substances from the duodenal papilla physically controlled?
By the hepatopancreatic sphincter
What are the endocrine functions of the pancreas?
Secretion of glucagon and insulin to regulate blood glucose levels
Where is insulin secreted?
Pancreatic islet beta cells
What is the exocrine function of the pancreas?
Digestive function via secretion from glands. Acinar cells secrete digestive enzymes while duct cells secrete bicarbonate
What is the function of pancreatic acinar cells?
Secrete enzymes for digestion.
What is the structure of pancreatic acinar cells?
Have apical zymogen granules, basal nucleus, and abundant rough ER
What cells of the pancreas secrete bicarbonate?
Pancreatic duct cells
