IB DP Biology: HL复习笔记6.3.1 Skin
Skin
- 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 and are then either swallowed (into the stomach) or expelled, therefore preventing infection
- Mucus also contains lysozyme enzymes which have antibacterial properties, providing more protection from invading microorganisms
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