Question

chapter 25: endocrine and immune systems: testing the iceman
page(s) 498 - 503 25.3. identify the immune system’s first, second, and third lines of defense.
complete the following passage regarding the three main strategies of the immune system for fighting infection.
the first line of defense includes defenses such as skin, mucus, and tears. the second line of defense involves the immune system, including such as neutrophils and macrophages. these responses are considered . the third line of defense includes responses such as the generation of antibodies and differentiation of into mature b cells and t cells.
lymphocytes nonspecific specific secondary innate phagocytes primary *
chemical external physical macrophages

Explanation:

The first line of defense consists of physical/chemical barriers (external defenses like skin, mucus, tears). The second line is the innate immune system with phagocytes (neutrophils, macrophages) and is nonspecific. The third line is specific, involving lymphocytes differentiating into B/T cells.

Answer:

The first line of defense includes physical/chemical defenses such as skin, mucus, and tears. The second line of defense involves the innate immune system, including phagocytes such as neutrophils and macrophages. These responses are considered nonspecific. The third line of defense includes specific responses such as the generation of antibodies and differentiation of lymphocytes into mature B cells and T cells.