Larry is taking a walk in the park. the pollen in the air makes him sneeze constantly. what line of defense is his immune system exhibiting?
a.
first line of defense
b.
second line of defense
c.
third line of defense
d.
fourth line of defense

Larry is taking a walk in the park. The pollen in the air makes him sneeze constantly. The line of defense that is his immune system exhibiting is that of "(A) first line of defense." There are only 3 lines of defense in the immune system. The first line of defense are a combination of physical and chemical barriers that prevent all types of foreign agents from penetrating the outer layer of the body. In this case, it is the nasal cavity.

A. first line of defense

Explanation:

  The immune system is a set of elements existing in the human body which interact with each other and aim to defend the body against disease, viruses, bacteria, microbes and others.  The human immune system serves as a barrier that protects us from unwanted elements (like bacterias, microbes etc), antigens, that try to invade our body. So, it represents the defense of the human body.  The body's defense process through the immune system is called the immune response and there are 2 types of immune responses: innate, natural or non-specific and acquired, adaptive or specific.

   Innate or natural immunity is our first line of defense. This type of immunity is already born with the person, represented by physical, chemical and biological barriers.  This is case of Larry, which the pollen (antigen) got in contact with the barrier of Larry's body, which is the mucus: a fluid produced by the body that has the function of preventing microorganisms from entering the respiratory system.