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First-Line Defenses: Chemical Barriers definitions

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  • Sebum
    An oily substance produced by sebaceous glands that lowers skin pH to inhibit microbial growth.
  • Sweat
    A fluid secreted by sweat glands containing lysozyme, which degrades bacterial cell walls.
  • Earwax
    A mixture containing sebum and keratin that controls pH and physically blocks microbes.
  • Saliva
    A fluid in the mouth rich in enzymes like lysozyme that inhibit microbial growth.
  • Gastric Juice
    A highly acidic stomach fluid containing hydrochloric acid and enzymes that kill bacteria.
  • Antimicrobial Peptides
    Short amino acid chains with antimicrobial activity, disrupting microbial membranes.
  • Defensins
    Positively charged antimicrobial peptides that cause microbial membrane lysis.
  • Lysozyme
    An enzyme found in various body fluids that degrades bacterial cell walls.
  • Sebaceous Glands
    Skin glands that produce sebum, contributing to the chemical barrier against microbes.
  • Perspiration
    The process of sweating, which helps remove microbes from the skin surface.
  • Keratin
    A protein in skin cells that creates a dry environment, aiding in microbial defense.
  • Hydrochloric Acid
    A component of gastric juice that lowers stomach pH to kill ingested bacteria.
  • Epithelial Cells
    Cells that produce antimicrobial peptides to protect skin and mucous membranes.
  • Bacteriocins
    A type of antimicrobial peptide produced by bacteria to inhibit the growth of similar or closely related bacterial strains.
  • Cathelicidin
    An antimicrobial peptide that disrupts microbial membranes, part of innate immunity.