How does the stomach contribute to the body’s defence against pathogens?

Sourav PanNovember 13, 2024

Answered

The stomach contributes significantly to the body’s defense against pathogens primarily through its acidic environment and various antimicrobial mechanisms. Here are the key roles it plays:

Acidic Environment

1. Gastric Acid Production: The stomach secretes hydrochloric acid (HCl), creating a highly acidic environment with a pH typically ranging from 1.5 to 3.5. This acidity is crucial for killing most ingested pathogens, including bacteria and viruses. Studies have shown that normal gastric acidity can kill over 99.9% of various gram-negative bacilli within 30 minutes of exposure.
2. Pathogen Inactivation: The acidic conditions in the stomach effectively inactivate many harmful microorganisms, preventing them from surviving the journey through the gastrointestinal tract and establishing infections in the intestines.

Antimicrobial Substances

1. Antimicrobial Peptides: The gastric mucosa produces various antimicrobial peptides that further enhance the stomach’s ability to neutralize pathogens. These peptides can disrupt bacterial cell membranes, leading to bacterial death.
2. Fatty Acids and Monoglycerides: The stomach also contains fatty acids and monoglycerides that exhibit bactericidal properties against pathogens like Helicobacter pylori. These compounds can be released from dietary fats and contribute to the antimicrobial activity within the gastric contents

Mucosal Defense

1. Mucus Layer: The stomach is lined with a protective mucus layer that serves as a barrier against both mechanical damage and pathogen invasion. This mucus traps pathogens and helps prevent them from adhering to the gastric epithelium.
2. Nitrite Compounds: Salivary nitrites can be converted into reactive nitrogen compounds under acidic conditions in the stomach, which may enhance the killing of certain pathogens, including some nosocomial strains.

Immune Response

1. Immune Cells: The gastric mucosa contains immune cells that can respond to pathogens that manage to survive the acidic environment. These cells play a role in recognizing and eliminating invaders, contributing to the overall immune defense of the gastrointestinal system.
2. Inflammatory Response: If pathogens breach the mucosal barrier, an inflammatory response can be initiated, recruiting additional immune cells to combat infection.