Ch. 26 - Innate Immunity: Broadly Specific Host Defenses

Question 1

What are the human body’s 3 lines of defense?

Answer 1

First line of defense keeps pathogens outside or neutralize them before infections begin. (Skin, mucous membranes, antimicrobial agents)

Second line of defense slows or contains infections when the first line fails (inflammation, fever, phagocytes, NK cells)

Third line of defense are WBCs that target specific pathogens for destruction (memory component that remembers pathogen. Humoral and cellular immunity)

Question 2

What are the 3 innate WBCs?

Answer 2

Basophil
Eosinophil
Mast cells

Question 3

Basophil

Answer 3

Granulocyte that releases histamines that causes inflammation.

Question 4

Eosinophil

Answer 4

Granulocyte that kills parasites with oxidative burst.

Question 5

Mast cells

Answer 5

Agranulocyte that kills infected cells (often virus-infected) via cytolysis or apoptosis)

Question 6

What are 4 WBCs that are part of innate and adaptive immunity?

Answer 6

Neutrophil
Monocyte
Dendritic cell
Natural killer (NK) cell

Question 7

Neutrophil

Answer 7

A granulocyte that phagocytizes bacteria and fungi.

Question 8

Monocyte

Answer 8

Agranulocyte that is a precursor to macrophages. Some macrophages are fixed in certain organs while other wander tissues causing inflammation. All perform phagocytosis.

Question 9

Dendritic cell

Answer 9

Many surface projectiles in the skin, respiratory, and intestinal mucosa that phagocytizes bacteria and presents antigens to T cells.

Question 10

Natural killer (NK) cell

Answer 10

Agranulocyte (LYMPHOCYTE) that kills cancer cells and virus-infected cells.

Question 11

What are the 3 adaptive WBCs?

Answer 11

Natural killer cells
Plasma cell, B cells
T cells (T helper cell, Cytotoxic T lymphocytes, T regulatory cell)

Question 12

Plasma cell, B cell

Answer 12

Agranulocyte (LYMPHOCYTE) that recognizes antigens and produces antibodies.

Question 13

T cells

T helper cell, Cytotoxic T lymphocyte, T regulatory cell

Answer 13

Agranulocyte:

T helper cells secrete cytokines. They are CD4+ cells that bind MHC class II molecules on antigen-presenting cells.

CTLs recognize and kill specific “non self.” They are CD8+ cells that bind to MHC class I molecules.

T regulatory cells that do not correctly recognize “self” cells.

Question 14

Immunity (resistance)

Answer 14

Immunity or resistance is the ability to ward off disease.

Question 15

Immunity (susceptibility)

Answer 15

Lack of resistance to a disease

Question 16

Innate immunity

Answer 16

Innate immunity is present at birth. It is a rapid dense mechanism against ANY pathogen.

Question 17

Adaptive immunity

Answer 17

Immunity or resistance to a specific pathogen. It is slow to respond and has a memory component. It is acquired throughout our lifetime.

Question 18

Innate immunity

Answer 18

An immune system that you’re born with. It includes physical barriers, phagocytosis cells, inflammation and fever. It is non-specific (defined pathogens are not targeted). It represents the first and second lines of defense.

Question 19

Adaptive immunity

Answer 19

It is acquired throughout life. It targets specific pathogens resulting from prior exposure and memory. It represents the third line of defense when the innate immune system fails to stop the pathogen.

Question 20

List the differences between innate immunity and adaptive immunity.

Answer 20

Innate immunity: immediate non-specific response. The response is the same regardless of the pathogen. It does NOT require previous exposure and has a noninducible ability to recognize and destroy an individual pathogen.

Adaptive immunity: slow to develop, but a very specific response. It depends on previous exposure to the pathogen and is directed toward an individual molecular component of the pathogen (antigen).

Question 21

What is natural host resistance?

Answer 21

It is normal microbiota that helps the host resist pathogens (particularly on the skin & gut d/t COMPETITIVE EXCLUSION). However, the ability of microbes to cause disease varies between species.

Note: competitive exclusion states that 2 species cannot coexist in the same ecological niche for long d/t competition for limited resources.

Question 22

Why is the infection site considered a barrier to pathogenic invasion?

Answer 22

The infection site is crucial in determining the routes of infection. Also, different pathogens invade different tissues.