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Oct 15
The stomach is a muscular organ located in the upper abdomen, between the esophagus and the small intestine. It is shaped like a J and is divided into four main regions: the cardia, fundus, body, and pylorus.
The inner lining of the stomach is made up of folds called rugae, which allow the stomach to expand and contract as it digests food. The stomach also contains gastric glands that secrete digestive enzymes and hydrochloric acid to break down food.
The stomach is surrounded by layers of muscle that contract and relax to mix and churn food, forming a semi-liquid substance called chyme. The lower part of the stomach, called the pylorus, connects to the small intestine through the pyloric sphincter, which regulates the flow of chyme into the small intestine.
Overall, the structure of the stomach is designed to efficiently break down food and extract nutrients for absorption into the bloodstream.
The inner lining of the stomach is made up of folds called rugae, which allow the stomach to expand and contract as it digests food. The stomach also contains gastric glands that secrete digestive enzymes and hydrochloric acid to break down food.
The stomach is surrounded by layers of muscle that contract and relax to mix and churn food, forming a semi-liquid substance called chyme. The lower part of the stomach, called the pylorus, connects to the small intestine through the pyloric sphincter, which regulates the flow of chyme into the small intestine.
Overall, the structure of the stomach is designed to efficiently break down food and extract nutrients for absorption into the bloodstream.
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Google Gemini AI
Oct 15
Macroscopic Structure
- Fundus: Dome-shaped region superior to the esophageal opening.
- Body: Main central portion.
- Antrum: Lower, funnel-shaped portion leading to the pyloric canal.
- Pyloric Canal: Narrow, tubular outlet.
- Pylorus: Muscular sphincter at the opening of the pyloric canal.
Microscopic Structure
Mucosa (Innermost Layer)
- Surface Epithelium: Columnar epithelium with mucus-producing goblet cells.
- Gastric Pits: Invaginations lined with surface epithelium.
- Gastric Glands: Tubular glands within the pits. Contain three types of secreting cells:
- Parietal Cells: Produce hydrochloric acid (HCl).
- Chief Cells: Produce pepsinogen, a precursor to pepsin.
- Mucous Neck Cells: Produce mucus.
Submucosa
- Connective tissue layer.
- Contains blood vessels, nerves, and lymphatic vessels.
Muscularis Externa
- Three layers of smooth muscle:
- Outer Longitudinal Layer:
- Middle Circular Layer:
- Inner Oblique Layer: These layers allow for peristaltic contractions.
Serosa (Outermost Layer)
- Outermost mesothelium-lined layer.
- Attached to the greater omentum.
Additional Features
- Gastric Folds (Rugae): Long, longitudinally oriented folds in the mucosa and submucosa that increase the surface area for digestion.
- Pyloric Valve: Sphincter at the junction of the antrum and pyloric canal that prevents backflow of stomach contents.
- Gastric Acid Pocket: Region of the fundus that has a higher concentration of parietal cells and secretes more HCl.
- Fundus: Dome-shaped region superior to the esophageal opening.
- Body: Main central portion.
- Antrum: Lower, funnel-shaped portion leading to the pyloric canal.
- Pyloric Canal: Narrow, tubular outlet.
- Pylorus: Muscular sphincter at the opening of the pyloric canal.
Microscopic Structure
Mucosa (Innermost Layer)
- Surface Epithelium: Columnar epithelium with mucus-producing goblet cells.
- Gastric Pits: Invaginations lined with surface epithelium.
- Gastric Glands: Tubular glands within the pits. Contain three types of secreting cells:
- Parietal Cells: Produce hydrochloric acid (HCl).
- Chief Cells: Produce pepsinogen, a precursor to pepsin.
- Mucous Neck Cells: Produce mucus.
Submucosa
- Connective tissue layer.
- Contains blood vessels, nerves, and lymphatic vessels.
Muscularis Externa
- Three layers of smooth muscle:
- Outer Longitudinal Layer:
- Middle Circular Layer:
- Inner Oblique Layer: These layers allow for peristaltic contractions.
Serosa (Outermost Layer)
- Outermost mesothelium-lined layer.
- Attached to the greater omentum.
Additional Features
- Gastric Folds (Rugae): Long, longitudinally oriented folds in the mucosa and submucosa that increase the surface area for digestion.
- Pyloric Valve: Sphincter at the junction of the antrum and pyloric canal that prevents backflow of stomach contents.
- Gastric Acid Pocket: Region of the fundus that has a higher concentration of parietal cells and secretes more HCl.
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