Question

To which type of barriers under innate immunity, do the saliva in the mouth and the tears from the eyes belong?
A) Physiological barriers
B) Physical barriers
C) Cytokine barriers
D)Cellular barriers

Answer 1

Hint: The immune system is the body's defense mechanism against various infections. Many cells and organs in our body work together to protect the body from these infections. White blood cells which are also called leukocytes play an important role in the immune system. Human beings have three types of immunity namely, innate, adaptive, and passive immunity.

Complete answer:
Innate immunity is the immunity everyone is born with innate or natural immunity. It is a type of general protection. An example is the skin acts as a barrier to block germs from entering the body.

Physiological barriers: They provide the crucial first line of defense against various pathogens. An example is our stomach uses hydrochloric acid to break down the food molecules. Due to this strongly acidic environment, most of the germs that enter our body along with the food are being killed even before the further process is carried on. Saliva in our mouth and tears in our eyes has an antibiotic property which does not allow the growth of pathogens even if they are exposed all day.

Physical barrier: These are the first line of defense. Skin acts as a physical barrier to the entry of pathogens. The mucus coating in our nose and ear acts as a protective barrier which helps in trapping the pathogen before it gets inside our body.

Cytokine barriers: When there is a virus invasion in our body, proteins are secreted which are called as interferons that develop a coating around the infected cell and thereby preventing the cells around it from any further infections.

Cellular barriers: Even though there are physical and physiological barriers, certain pathogens still can enter our body. The cells involved in this barrier are leukocytes which are WBC, neutrophils, lymphocytes, basophil, eosinophil, and monocytes.

Therefore the correct answer is option ‘A’.

Note: Adaptive or active immunity is being developed throughout our lives like when we are exposed to diseases or when we are immunized against them with vaccines. Whereas passive immunity lasts for a short period of time. An example is where the antibodies in a mother's breast milk can give a baby temporary immunity to diseases the mother has been exposed to.