Which line of defense first applies to each term?
1. ___ Inflammation
2. ___ Monocytes
3. ___ Lactoferrin
4. ___ Fever
5. ___ Dendritic cells
6. ___ Alpha interferon
7. ___ Mucous membrane of the digestive tract
8. ___ Neutrophils
9. ___ Epidermis
10. ___ Lysozyme
11. ___ Goblet cells
12. ___ Phagocytes
13. ___ Sebum
14. ___ T lymphocytes
15. ___ Antimicrobial peptides


A. First line of defense
B. Second line of defense
C. Third line of defense

Verified step by step guidance

1. Step 1: Understand the three lines of defense in the immune system. The first line of defense includes physical and chemical barriers that prevent pathogen entry, such as skin, mucous membranes, and secretions. The second line of defense involves innate immune responses like inflammation, phagocytes, and fever. The third line of defense is the adaptive immune response, involving specific cells like T lymphocytes and antibodies.
2. Step 2: Identify terms that are physical or chemical barriers (first line of defense). These include structures or substances that block or neutralize pathogens before they enter the body tissues, such as the epidermis, mucous membranes, lysozyme, sebum, goblet cells, and antimicrobial peptides.
3. Step 3: Identify terms related to innate immune responses (second line of defense). These are non-specific responses activated after pathogens bypass the first line, including inflammation, monocytes, neutrophils, phagocytes, fever, dendritic cells, and alpha interferon.
4. Step 4: Identify terms related to the adaptive immune response (third line of defense). This line involves specific recognition and memory, primarily mediated by lymphocytes such as T lymphocytes.
5. Step 5: Assign each term to its corresponding line of defense based on the above classifications, ensuring that physical/chemical barriers are marked as first line, innate immune components as second line, and adaptive immune cells as third line.

Key Concepts

Lines of Defense in the Immune System

The immune system protects the body through three lines of defense: the first line includes physical and chemical barriers like skin and mucous membranes; the second line involves innate immune responses such as inflammation and phagocytes; the third line is the adaptive immune response, featuring specific cells like T lymphocytes that target pathogens precisely.

Innate Immunity Components

Innate immunity provides immediate, non-specific defense against pathogens. It includes physical barriers (skin, mucous membranes), chemical factors (lysozyme, lactoferrin), and cellular responses (neutrophils, monocytes, dendritic cells) that recognize and attack invaders without prior exposure, forming the second line of defense.

Adaptive Immunity and Specific Immune Responses

Adaptive immunity is a specific defense mechanism activated after exposure to a pathogen. It involves lymphocytes like T cells and B cells that recognize specific antigens, leading to targeted attacks and immunological memory, which constitutes the third line of defense and provides long-lasting protection.