Stomach
Structure and Function
Structure
Basically a sac that can expand and shrink a bit (because of the rugae, folds in the stomach walls). It has two sphincters, the gastro-oesophageal and the pyloric (which is just made out of thickening of the circular muscle layer).
There are enzyme and HCl secreting cells, as well as mucus secreting ones.
Functions:
- Storage: 1500ml capacity, collapsible and expandable (rugae)
- Formation: semifluid chyme
- Protection (HCl), kills bacteria, Mucus, prevents damage to stomach from alcohol, aspirin, NSAIDs, etc.
- Absorptive: Small amounts of H2O, alcohol, drugs
- Mechanical Digestion: muscles
- Secretive: H2O, enzymes, hormones
| Type | Location | Secretion |
|---|---|---|
| Parietal | Body + Fundus | HCl and Intrinsic Factor |
| Chief | Body + Fundus | Pepsinogen |
| Goblet Cells | Everywhere | Mucus |
| G Cells | Antrum | Gastrin |
| Enterochromaffin-like Cells | Antrum | Histamine |
| D Cells | Antrum | Somatostatin |
Arterial and Venous supply
File:Stomachblood.png Left gastric: Lesser curvature Right Gastric: Lower part of stomach Right Gastroepiploic: Inferior aspect of the greater curvature Left Gastroepiploic: Superior aspect of the greater curvature Short Gastrics: Fundus
Nervous Supply
Parasympathetic Left Vagus nerve applies anteriorly on the left hand side of stomach Right Vagus nerve applies posteriorly to the right hand side of stomach Functions: essentially the motor activities; secretion, digestion and muscular. It is this nerve that make the stomach churn and peristaltise food.
Sympathetic Branches of the celiac plexus.????? From the sphlanchnic nerve. The only sympathetic fibres in the stomach (pain fibres) Functions: contains the efferent pain fibres. When stomach "drops" in fear, this nerve activates that.
Lymph
Left gastric nodes: Drain the lesser curvature and 2/3 of the body. Pancreaticosplenic, gastroepiploic and pyloric nodes: Rest of stomach.
Histology
Both plexi above are parasympathetic