Is the integumentary system second and third line of defense against infection?

The integumentary system is only the first line of defense.

First line

-Physical barriers: Skin (consisting of epidermis, dermis, and hypodermis), mucous membranes, stomach acid, saliva, and tears.

-Chemical barriers: Sebum, sweat, tears, lysozyme, and gastric juices.

-Microbiota: Commensal microorganisms that help protect against pathogenic microbes.

Second line

-Innate immune response: Immediate response that does not require prior exposure to a pathogen and is mediated by phagocytic cells, natural killer cells, and inflammation.

Third line

-Adaptive immune response: Antigen-specific response that is mediated by B cells (which produce antibodies) and T cells (which attack infected cells and coordinate immune responses). This defense is antigen-specific and provides long-term immunity to specific pathogens.