In the context of our non-specific defenses:
Exterior defense:
- Skin
- Nasal mucus
- Saliva in mouth
Interior defense:
- Phagocytes
- Natural killer cells
- Digestive juices
The exterior defenses are those that occur on the outside of our bodies and act as the first line of defense against pathogens trying to enter. These include the skin, which forms a physical barrier, as well as nasal mucus and saliva in the mouth, which contain enzymes and antibodies that help trap and kill pathogens.
On the other hand, the interior defenses work within our bodies to combat pathogens that may have breached the exterior defenses. Phagocytes are specialized white blood cells that engulf and destroy pathogens. Natural killer cells are another type of white blood cell that can directly kill infected cells. Additionally, digestive juices in the stomach contain acids and enzymes that can kill ingested pathogens before they can cause harm.
