3.6 Gastrointestinal Tract

This is a historical learning note and may contain outdated or incomplete understanding.

1. Digestive Tract

1.1. Oral Cavity

1.1.1. Salivary Glands

Antibacterial, anti-inflammatory, pain-relieving.

1.1.2. Tonsils

Surrounded by immune tissue.

1.2. Esophagus

It enters the stomach at an angle rather than in a straight line, to prevent abdominal pressure from pushing stomach contents back up into the esophagus.

1.3. Stomach

The two sides have different lengths, for handling solids and liquids separately.

1.4. Small Intestine

It folds repeatedly to increase surface area. Digested food passes through the liver for detoxification before entering the bloodstream. Carbohydrates are broken down by digestive enzymes and enter the blood; fat is absorbed by the lymphatic system; protein is broken down into amino acids. Food allergy means the small intestine lacks certain digestive enzymes (such as lactase), or protein and fat enter the lymphatic system together and trigger an immune response. Stomach rumbling may also be the small intestine clearing out incompletely digested material.

1.5. Large Intestine

It contains many gut microorganisms and processes food residue that the small intestine cannot fully absorb or digest. It takes three days for the entire large intestine to empty. Defecation requires cooperation between the internal and external sphincters. The internal sphincter is responsible for the urge to defecate, while the external sphincter is controlled by the brain. Squatting is good for defecation.

1.5.1. Bacteria

Bad bacteria: Salmonella, Helicobacter pylori, Toxoplasma. Probiotics contain beneficial bacteria, while prebiotics help beneficial bacteria reproduce.

2. References

Is “Chronic Superficial Gastritis” Serious, and Does It Need Treatment? - Sina Health What Foods Are Good for Superficial Gastritis? - Zhihu A Step-by-Step Guide to Reading a Gastroscopy Report - Haodf Preparing for Your First Colonoscopy - DXY My First Colonoscopy - Zhihu A Step-by-Step Guide to Reading a Stool Test Report - Zhihu My Recovery from Stomach Problems (Indigestion and Acid Reflux) - Zhihu