How is the oesaphagus histologically identified??
The oesophagus is easily identified by the stratified squamous non-keratinising epithelium in its mucous membrane.
What is the job of the smooth muscle in the digestive system??
its job is to try and keep the epithelium in contact with the content that is going through the lumen
what is the job of the external muscle in the digestive system ??
to propel the food throughout the system. keep it moving through the system
what's the next part called in the digestive system after the stomach ?
function of the stomach??
The stomach mixes and churns the food into a soft fluid (chyme) and continues the digestive process by adding enzymes.
what is the rugae??
the longitudinal folds of the mucous membrane
when are the rugae visible??
when the stomach is empty
Muscous neck cells
(acid producing cells)
surface mucous cells
Mucous Neck Cells ??
Mucous Neck Cells is the name given to the cells which line the upper parts of the gastric pits and it is here that the stem cells are located which divide to replace the cells approximately every 3 days.
The mucous secretion protects the cells from the acidic and enzymatic properties of the gastric juices and of the ingested food and abrasion from the rougher components of the chyme.
Cells of the Immune System
The gastric mucosa also contains numerous cells of the immune system. Lymphocyte, plasma cells and lymphoid follicles may be seen especially in the pyloric region.
what kind of cell is this??
What kind of cell is this ??
Chief Cell ??
The lower regions of the gastric glands contain enzyme secreting chief cells. They contain large quantities of RER and therefore secrete protein which is released in the form of zymogen granules which contain digestive enzymes and proteases. The acid environment of the stomach activates the enzyme pepsin which cleaves peptide bonds and thus forms smaller peptides which may be digested to amino acids in the small intestine. The chief cells are stimulated by the vagus nerve and enteroendrocrine cells in the base of the pits.
Parietal Cells have 4 features, what are they?
- Abundant mitochondria (40% cell volume) to provide ATP to pump H+ ions into the lumen of the canaliculus
- An intercellular canaliculus formed by the invagination of the apical cell surface which is lined by microvilli
- An H+, K+-ATPase rich tubovesicular system when the cell is in the resting state
- Intrinsic factor is also secreted by the parietal cells and is a glycoprotein that complexes with vitamin B12 which is necessary for its subsequent absorption in the ileum. Malabsoprtion leads to pernicious anaemia.
They are found in the neck of the gastric glands.
Acid secretion is stimulated by the release of gastrin from the enteroendrocrine cells
H+ and Cl- are actively pumped into the lumen, water enters the cell by osmosis and this combines with CO2 forming carbonic acid which dissociates into bicarbonate ions and H+ ions. The bicarbonate enters the blood raising the pH but the effect is quite small.
Functions of Gastroenteroendocrine Cells ??
- The regulation of water, electrolyte metabolism and enzyme secretion
- The regulation of gastric motility and mucosal growth
- The stimulation and release of other peptide hormones
Peptide hormones regulate the gastrointestinal system and are produced by gasteroenteroendocrine cells. These cells are dispersed throughout the mucosa of the stomach and intestine. Neuroendocrine mediators are also present.
Ascending colon of the large intestine