Human Defence Systems Against Pathogens

The video explains the body's defense mechanisms against pathogens. It starts with the skin, the largest organ, acting as a physical barrier. The respiratory system uses mucus and cilia to trap and expel invaders. Blood clots prevent infections in wounds, while stomach acid kills ingested pathogens. Friendly bacteria in the intestines also play a role. If pathogens bypass these barriers, the second line of defense, including white blood cells and antibodies, takes over to protect the body.

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