Question

Explain the role of physiological barriers of innate immunity.

Answer 1

(i) Fever: A raised body temperature inhibits the growth of germs and activates the body's defence mechanism; it is caused by toxins or by pyrogens released by WBCs.

(ii) Acidic pH: The stomach (pH about 3–5) kills most bacteria swallowed with food; acidic secretions of oil and sweat glands (pH 3–5) on the skin do not let microorganisms survive for long. 

(iii) Body secretions: Saliva, tears and perspiration contain lysozymes that kill bacteria.