Cells of the Stomach
A single layer of epithelial cells forms the inner most later of the
stomach, called the mucosa. The mucosa is marked by depressions
called gastric pits (these are lined with epithelial cells). The gastric gland
is at the bottom of the pit, which contain multiple cell types: mucous
cells, stem cells, parietal cells, chief cells, and G cells (enteroendocrine
cells).
Cells of the gastric pit in the mucosa. This work by Cenveo is licensed under a Creative Commons Attribution
3.0 United States (http://creativecommons.org/licenses/by/3.0/us/).
Exocrine Function
Digestion in the stomach requires a combination of acid and pepsin. In
the glands of the stomach, chief cells secrete pepsinogen, which is
converted to pepsin, as well as gastric lipase, which is used for digestion
of fats. Parietal cells secrete hydrochloric acid (HCl) as well as
intrinsic factor.The gastric mucous cells associated with the surface and
neck of the gastric pit secrete a thick mucus that is more alkaline than
the mucus produced by goblet cells found elsewhere in epithelial tissue.
This helps provide a protective mucosal barrier from the acid and
protein enzymes in the gastric juice.
Endocrine Function
Enteroendocrine cells tightly control regulation within the digestive
system. Collectively, these cells are found in the organs of the digestive
system (entero- inside) and release hormones and paracrine signals
which regulate production of digestive chemicals and also influence the
nervous system for global regulation of digestion. Within the stomach,
the enteroendocrine cells are called G-cells.
G-cells secrete the signaling molecules including gastrin. Gastrin
signals parietal cells (HCl producing) and chief cells (enzyme producing)
to regulate production and alters stomach motility by altering the
sphincter function on either side of the stomach. G cells also secrete
other paracrines – serotonin, histamine, somatostatin, and other
hormones, which regulate digestion.
Overview of Stomach Cells
Structure
Action
Outcome
Gastric
epithelial
cells
Structure
of
stomach lumen
Chief cells
Secrete
pepsinogenSecrete
gastric lipase
Pepsin (activated form) breaks
proteins
down
into
peptidesBreaks
down
triglycerides into fatty acids and
monoglycerides
G cells
Secrete gastrin
Activates secretion of HCl by
parietal cells and pepsinogen by
chief cells; contracts lower
esophageal sphincter, enhances
stomach motility, and relaxes
the Maintains
mucosa
structure
of
the
Structure
Action
Outcome
pyloric sphincter
Parietal
cells
Secrete HClSecrete Kills
microbes;
denatures
intrinsic factor
proteins, transforms pepsinogen
into pepsinEnables vitamin B12
absorption, which is necessary for
red blood cell formation