Question

Which of the following is classified as a physiological barrier of the innate immune system?

• A. Skin
• B. Mucus coating of the respiratory tract
• C. Gastric HCl in the stomach
• D. Neutrophils

Answer 1

Answer:

C. Gastric HCl in the stomach

• Physiological barriers prevent microbial growth through chemical means. This includes gastric HCl (which has a low pH to kill pathogens), saliva, and tears. Skin and mucus coatings are considered physical barriers.