Lecture 21: The Stomach and Pancreas Flashcards
what is the shape of the stomach?
J-shaped organ
where is the stomach located?
base of the esophagus
where does the esophagus pass through?
the diaphragm via the esophageal hiatus
what does the lower esophageal sphincter do?
prevents reflux
what are the main parts of the stomach?
- cardia
- fundus
- body
- pylorus
what are curvatures?
attachment points for omentum
lesser omentum connects to lesser curvature
greater omentum connects to greater curvature
what does the greater omentum have?
- lots of adipose
- immune cells
what is the muscularis modified for?
Motility
has 3 layers
- inner oblique
- middle circular
- outer longitudinal
what does the inner surface of the stomach have?
Rugae
- temporary folds that allow for expansion of the stomach
- important for storage function
what is the structure of rugae?
folded core of submucosa with overlying mucosa
how is the mucosa of the stomach modified?
the mucosa has simple columnar epithelium
- in-folding increases surface area for secretion
- the glands are permanent
why do we need glands?
we need acids and enzymes for digestion, mucus for protection, hormones for regulation
what are the gastric glands and their secretions?
parietal cells - secrete acid and intrinsic factor
G cells - secrete hormones (gastrin)
Chief cells secrete pepsinogen (inactive precursor of pepsin)
what is the structure of chief cells?
chief cells produce enzymes
- abundant rough endoplasmic reticulum
- apical zymogen granules (contain enzymes)
- basal nucleus
what is the structure of parietal cells?
parietal cells produce acid
- pump ions (H+)
- abundant mitochondria
- central nucleus
- folded structure to increase surface area
what regulates stomach function?
- endocrine control
- neural control
how does endocrine control regulate the stomach?
- endocrine cells in the mucosa
- gastrin and ghrelin secreted in the bloodstream
how does neural control regulate the stomach?
Enteric nervous system for local reflexes
Central nervous system modulates ENS for long neural reflexes
what type of control does chyme need from the stomach to small intestine?
there needs to be a controlled release of chyme from stomach into the small intestine. this is done by the pyloric sphincter
what happens to chyme after is enters the small intestine?
- it requires further digestion by enzymes
- protection from acidic chyme by mucus and neutralising acid
so mucus is provided by glands in the submucosa of the duodenum and enzymes and bicarbonate are provided by the pancreas
what is the location of the pancreas?
- head in C-shaped duodenum
- head toward spleen
- posterior to the stomach
- duct into duodenal lumen
where does the pancreas sit?
retroperitoneal
where is the bile duct?
bile duct meets the pancreatic duct and the hepatopancreatic ampulla
where is the duodenal papilla?
projects into the duodenal lumen
what is the release of the pancreas controlled by?
hepatopancreatic sphincter
what is the endocrine function of the pancreas?
- pancreatic islet alpha cells secrete glucagon
- pancreatic islet beta cells secrete insulin
what is the exocrine function of the pancreas?
- acinar cells secrete digestive enzymes
- duct cells secrete bicarbonate
what is the structure and function of pancreatic acinar cells?
structure:
- apical zymogen granules
- basal nucleus
- abundant rough ER
function:
- secrete enzymes
(similar to chief cells of the stomach and salivary acinar cells)
