Lecture 24 Flashcards
What two parts of the esophagus help prevent food leaving the stomach?
The esophageal hiatus and lower esophageal sphincter act to keep the food in the stomach while digestion is going on. A small portion of the esophagus continues into the abdominal cavity.
What functions ddoes the stomach provide and how?
The stomach functions for storage and as such has an expanded lumen and sphincters as well as allowing distension. It has motility of smooth muscle and sphincters to allow for mechanical digestion and also secretes strong chemicals (acids and enzymes) as well as has protective epithelium for chemical digestion.
What are the regions of the stomach? What is the extra muscle region? How does it being crunched up help?
The cardia region is where the esophagus enters the stomach the fundus is the superior bump portion , the body is the main portion and the pylorus is the entryway to the duodenum (closed off by a sphincter). It possesses an additional oblique muscle layer (also contains longitudinal and circular as normal).
By being scrunched up (rugae are the names of the folds in the submucosa layer, they allow for expansion of the stomach).
How is the stomach mucosa modified? What dooes each cell do and how can we recognise them?
The stomach mucosa is modified for secretion and protection, to have enough cells the cells furrow and form pits known as gastric glands (the upper cells are mucous cells, followed by chief cells (inactivated enzymes until they reach the lumen, hence no protection needed till the end of the gland, will have granules), parietal cells (acid, lots of mitochondria due to setting up on concentration gradients) and then endocrine cells (hormones). There are progenitor cells are found below the gastric glands near the muscularis mucosae because this is the safest location.
What happens to parietal cell structure when they change from resting to active.
Resting parietal cells have a small surface area with lots of vesicles and membrane proteins, when active they instead have a large points of smooth surface area.
What are the main smooth muscle points for the stomach?
The smooth muscle of the stomach has slow non tiring contraction with slight basal tone and gap junctions link the cells and there are many receptors, when filled mechanical digestion occurs.
summarise the specialisations of the stomach:
secretion: enzymes, acid, hormones, control of secretion
Protection: mucous secreting cells
Movement: extra muscle layer
storage: regions of the stomach mscle, rugae.
Controlled release: muscle, nervous tissue and endocrine cells.
What does the pancreas do?
The food which leaves the stomach will be fine and very acidic. This means it needs cells with protection and a way to neutralise the pH. The pancreas has the head in the C shaped dueodenum and is behind the stomach, it has a duct into the duodenal lumen. It contains secretory units and secretes exocrine enzymes with help from the gall bladder and the liver via the combined hepatopancreatic duct which enters into the hepatopancreatic ampulla and is released into the greater duodenal papilla via control from the sphincter of Oddi. The pancreas also secretes endorine enzymes (e.g insulin) via the islets of langerhans.
It is essentially the same as the parotid gland. Acinar cells secrete the enzymes and duct cells produce bicarbonate to neutralise the acid.
What nervous system controls the stomach?
enteric nervous system.
