Three parts of the first line of defense that the body uses to protect itself against infections include skin, mucus, and stomach acid.
The first line of defense of the immune system are different types of chemical and physical barriers that protect us from infections caused by pathogenic microorganisms.
The first line of defense includes physical barriers such as the epidermis (skin) or chemical barriers (e.g., stomach acid) that destroy microorganisms.
In conclusion, parts of the first line of defense include skin, mucus, and stomach acid.
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