Skin and Mucuous Membranes Are Your First Line of Defense
- Imagine you’re walking through a crowded city.
- Invisible pathogens surround you, but your body has a remarkable system to keep them out: skin and mucous membranes.
- These structures form the first line of defense, protecting you from infections.
Think of the skin as a fortress wall and mucous membranes as sticky nets that trap invaders.
The Skin: A Multifunctional Barrier
1. Physical Barrier
- The skin’s outermost layer, the epidermis, is made of dead cells packed with keratin, a tough protein.
- This layer is waterproof and nearly impenetrable, preventing pathogens from entering the body.
- Shedding of dead skin cells helps remove attached pathogens.
The epidermis constantly sheds dead cells, removing any pathogens that may have settled on its surface.
2. Chemical Barrier
- The skin isn’t just a physical shield; it also produces chemicals that deter pathogens.
- The sebaceous glands secrete sebum, which contains antimicrobial substances that inhibit bacterial growth.
- The skin has a slightly acidic pH (around 5.5), creating an unfavorable environment for many pathogens.
- Pathogens thrive in neutral or alkaline environments.
- The skin’s acidity is a key defense mechanism.
Mucous Membranes: Flexible and Protective
- Not all body surfaces are covered by skin, internal cavities and openings (like the respiratory, digestive, and urogenital tracts) require an alternative defence mechanism.
- Mucous membranes line these internal surfaces and protect against pathogen entry.
1. Physical Trapping
- Mucous membranes line areas of the body exposed to the external environment, such as the respiratory, digestive, and reproductive tracts.
- These membranes produce mucus, a sticky substance that traps pathogens and particles.
