Skin as a Barrier to Pathogens
- The skin and mucous membranes form a primary defence against pathogens that cause infectious disease
- Skin is the largest organ of the body and is covered in microorganisms that usually cause no issues, as they can't enter the body. Skin provides:
- A tough physical barrier that prevents entry of pathogens into our bodies
- Cuts in the skin are sealed by formation of blood clots to prevent entry of pathogens
- Chemical protection through the production of sebum from the sebaceous glands of the hair follicles
- Sebum is a chemical responsible for maintaining a low skin pH which inhibits the growth of microorganisms
- Mucous membranes are found lining vulnerable areas which may be a route for pathogens into the body
- This includes the airways, areas around the reproductive organs (foreskin and vagina) and the digestive system
- The membranes contain goblet cells which produce mucus containing glycoproteins
- Microorganisms and particles become trapped by the mucus
- The mucus is then swept along by the cilia of the ciliated epithelium upwards and is swallowed
- The mucus and any microorganisms will then be swallowed and destroyed by the acid in the stomach or expelled, therefore preventing infection
- Mucus also contains lysozyme enzymes which have antibacterial properties, providing more protection from invading microorganisms
Cilia and Goblet Cells Diagram
Ciliated epithelium contains cilia, a basement membrane, and goblet cells
