Chapter 12 Lecture Objectives

Identify three components of the first line of defense.

- intact skin - mucus - cilia - tears (containing lysozyme)

Describe two examples of how the normal microbiota contribute to the first line of defense.

-Even though the resident biota does not constitute an anatomical barrier, its presence can block the access of pathogens to epithelial surfaces and can create an unfavorable environment for pathogens by competing for limited nutrients or by altering the local pH. -the presence of a robust commensal biota "trains" host defenses in such a way that commensals are kept in check and pathogens are eliminated.

Outline the steps in phagocytosis

1. Chemotaxis- PAMPS and cytokines draw phagocytes to the area of the infection 2. Adhesion- Phagocytes use pattern recognition to identify and stick to foreign cells 3. Engulfment and Phagosome Formation- A vesicle forms as the membrane of the phagocyte engulfs the microbe with pseudopods (phagosome) 4. Phagolysosome Formation and Killing- the phagosome fuses with the lysosome and release chemicals to poison the ingested material 5. Destruction- phagolysosome uses destructive chemicals to destroy the microbe/antigen 6. Elimination- The small bits of undigestible debris are released from the macrophage by exocytosis.

Summarize the three lines of host defenses

1. First line- innate, nonspecific which includes: barriers to disease- physical, chemical, and genetic 2. Second-innate, nonspecific which includes: phagocytosis, inflammations, complement, interferon 3. Third- acquired, specific defenses which include: B and T lymphocyte

Outline the steps in inflammation

1. Injury and vasoconstriction 2. Vascular changes 3. Edema and pus formation 4. Scar and resolution

Name three kinds of blood cells that function in nonspecific immunity and the most important function of each. (focus on eosinophils, neutrophils, basophils, macropphages, dendritic cells)

1. Neutrophils- Phagocytes (react early in the inflammatory response) 2. Basophils- Involved in allergic response/Inflammatory response 3. Eosinophils- mainly invovled in eukaryotic parasitic infections also involved in allergic responses 5. Macrophages- largest phagocytes. antigen presenting cells found in tissue 6. Dendritic Cells- antigen presenting cells found in the lymph nodes. (characterized by large branchlike extensions of the cell membrane)

Compose one good overview sentence about the purpose and the mode of action of the complement system

26 blood protein that increase phagocytosis and cause inflammation and lysis of cells

Name two kinds of lymphocytes involved in specific immunity. (focus on T cells and B cells)

B-lymphocytes and T-lymphocytes

Name three types of antimicrobial proteins

Interferons, Complement, Antimicrobial Peptides

Define marker, and discuss its importance in the second and third line of defense.

Marker - extension on WBCs, "self" cells, and antigens that differentiate them from each other Important because when WBCs PRRs (Pathogen Recognition Receptor) comes into contact with "self" cells' "markers", the WBCs know to not destroy that cell. When WBCs PRRs come in contact with an antigen (pathogen), they identify the pathogen by contacting the pathogens "markers" or PAMPs (Pathogen Associated Molecular Pattern). Once the WBC recognizes the molecule to be an antigen (pathogen), it destroys the antigen (pathogen) thru phagocytosis.

Describe how bacterial structures (e.g., peptidoglycan, lipopolysaccharides, flagella, etc.) stimulate a non-specific immune response. (PAMP topic - pathogen associated molecular pattern). Define PAMP pathogen-assciated molecular patterns, PRR - pattern recognition receptor.

PAMP- Pathogen-associated molecular patterns: Molecules on the surfaces of many types of microbes that are not present on host cells that mark the microbes as foreign. PRR- Molecules on the surface of host defense cells that recognize PAMPS on microbes

Describe the structure and function of the lymphatic system.

Structure: The lymphatic system is a compartmentalized network of vessels, cells, and specialized accessory organs. It begins in the farthest reaches of the tissues as tiny capillaries that transport a special fluid (lymph) through an increasingly larger tributary system of vessels and filters (lymph nodes), and it leads to major vessels that drain back into the regular circulatory system. Function: 1. to provide a route for the return of extracellular fluid to the circulatory system proper; 2. to act as a "drain-off" system for the inflammatory response; and 3. to render surveillance, recognition, and protection against foreign materials through a system of lymphocytes, phagotyctes, and antibodies

Discuss the mechanism of fever and how it helps defend the body

The cause of fever is infection. Fever is initiated when circulation substances called pyrogenes reset the hypothalamic thermostat to a higher setting. -Fever inhibits multiplication of temperature-sensitive microorganisms such as the poliovirus, cold viruses, herpes zoster virus, and systemic and subcutaneous fungal pathogens -Fever impedes the nutrition of bacteria by reducing the availability of iron -Fever increased metabolism and stimulates immune reactions and naturally protective physiological processes. It speeds up hematopoiesis, phagocytosis, and specific immune reactions and helps specific lymphocytes hone in on sites of infection.

Define margination and diapedesis

margination- neutrophils stick to lining of the endothelium (a part of inflammation) diapedesis- neutrophils squeeze through the vessel wall.

State the role of interferon

causing change in genetic expression inhibit the expression of cancer genes