Question

12. Identify anatomic and physiologic barriers that defend the body against mi

Answer 1

Anatomical and physiological barriers provide first line defense against invading pathogens. They are non-specific and are components of the innate immune system.
Surface defense barriers: Skin, hair, and mucus
Internal defenses: Mast cells, Basophils, NK cells, Complement proteins, Monocytes, Neutrophils, and Macrophages

Skin contains keratinized cells and Langerhans cells which prevent the entry of pathogens.
Skin also secretes several liquids (Sweat and Sebum) which exhibit washing action. They also contain low pH.
Salivary glands in the Oral cavity secrete Lysozyme which kills bacterial cells.
Gastrointestinal tract secretes HCl which prevents the growth of pathogens.
Mucosal non-pathogenic flora prevents the colonization of harmful microbes by competitive exclusion.