Question

Shot / Long answer type questions.
The barriers in the innate immunity are given in the following table. Identify a, b, C, and d.

	Type of barrier		Barrier
(i)	physical	(a)	skin
(ii)	physiological	(b)	in the eye
(iii)	tears	(c)	interferon
(iv)	cellular	(d)	WBC

Answer 1

• 'a' is 'mucus coating of the epithelium lining the respiratory, gastrointestinal and urogenital tracts'. It is another type of physical barrier apart from the skin.
  
• 'b' is 'tears'. Acid in the stomach, saliva in the mouth, tears from eyes are physiological barriers.
• 'c' is cytokine. Virus-infected cells secrete proteins called interferons which protect non-infected cells from further viral infection, which is an example of cytokine barrier.
• 'd' is 'macrophages'. Along with WBCs, macrophages in tissues phagocytose and destroy microbes.