Chapter 21 exam review

innate (nonspecific) defense system

Constitutes the first and second lines of defense, first line being the external body membrane (skin and mucous membranes), and second line being antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders; inflammation is the most important mechanism)

Adaptive (specific) defense system

Third line of defense attacks particular foreign substances (takes longer to react than innate)

Leukocytosis

Increase numbers of WBC in bloodstream; 4-5X increase in neutrophils. It is the first step of phagocyte mobilization, triggered by leukocytosis-including factors released from injured cells

Margination 

The second step of phagocyte mobilization. During inflammation, endothelial cells of capillaries project cell adhesion molecules (CAMs) into the vessel lumen. These CAMs grab passing neutrophils, causing them to slow, roll, and cling to the vessel wall

Diapedesis

Neutrophils flatten and squeeze between endothelial cells, moving into interstitial spaces

Chemotaxis

The third step of phagocyte mobilization. Inflammatory chemicals act as chemotactic agents that promote positive chemotaxis of neutrophils toward injured area. Monocytes arrive later.

Apoptosis

programmed cell death

Histamine ??????

Chemical released by mast cells/basophils that promotes vasodilation and increased permeability (inflammation)

Pyrogen ?????

Substance (often from WBCs or pathogens) that raises body temperature, causing fever

Antigen

Substances that can mobilize adaptive defenses and provoke an immune response. Most are large, complex molecules not normally found in body (nonself)

Characteristic of antigens

-Can be a complete antigen or hapten (incomplete)

-Contain antigentic determinants

-Can be a self-antigen

Hapten

incomplete antigens, are molecules too small to be immunogenic by themselves

MHC I

Molecules on all nucleated cells that present endogenous antigens to cytotoxic T cells (CD8)

MHC II

Molecules only on some cells, on antigen-presenting cells (APCs) that present exogenous antigens to helper T cells (CD4)

Cytokine ?????

Small protein messenger released by immune cells to regulate immune responses (e.g interleukins, interferons)

Surface barriers

First step in line, Nonspecific external defenses that block pathogens from entering the body

What does the first line of defense include?

Skin and mucosae, along with their protective secretions (acid, enzymes, mucus, defensins)

Acid

Acidity of skin and some mucous secretions inhibits growth

Lysozyme

in saliva, respiratory mucus, and lacrimal fluid

Mucin

Sticky mucus that lines digestive and respiratory tract traps microorganisms 

Defenisns

Antimicrobial peptides that inhibit microbial growth

Internal defenses

Second step in line, nonspecific defenses that become necessary if microorganisms invade deeper tissues

What does the second line of defense include?

Phagocytes, NK cells, inflammation, antimicrobial proteins (interferons and complement), and fever

What are the steps of phagocyte mobilization?

1. Leukocytosis

2. Margination

3. Diapedesis

4. Chemotaxis

What are the steps of phagocytosis?

1. Adherence

2. Ingestion

3. Phagosomes fuses with lysosome

4. Digestion and killing of pathogen

5. Exocytosis of indigestible material