Micro 22 Unit 4 Chapter 16

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Innate Immunity

Back 1

- refers to defenses that are pressent at birth. They are always available to provide rapid responses to protext us against disease.

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Adaptive Immunity

Back 2

- specific response to a specific microbe once a microbe has breached the innate immunity defenses. It adjusts to handle a particular microbe.

Front 3

Toll-like receptors (TLRs)

Back 3

- Transmembrane protein of immune cells that recognizes pathogens and activates an immune response directed against those pathogens

Front 4

Pathogen-associated molecular patterns (PAMPs)

Back 4

Molecules present on pathogens and not self

- what TLRs attach to

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Cytokines

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a small protein released from human cells that regulates the immune response; directly or indirectly may induce fever, pain, or T cell proliferation

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macrophages

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a phagocytic cell; a mature monocyte.

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complement system

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- a group of serum proteins involved in phagocytosis and lysis of bactera

- consists of over 30 proteins produced by the liver that circulate in blood serum and within tissues throughout the body

- completes or assissts cells of the immune system in destroying microbes (part of innate immune system, but can be recruited into action by the adaptive immune system)

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interferons (define/fig. 16.14)

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- a specific group cytokines. Alpha- and beta- IFNs are antiviral proteins produced by certain animal cells in response to aviral infection.

1. Virall RNA from an infecting virus enters the cell.

2. The virus induces the host cell to produce interferon mRNA (IFN-mRNA) which is transated into alpha and beta interferons.

3. Interferons make contacts with uninfected neighboring host cells, where they bind either to the plasma membrane or to nuclear receptors. Interferons induce the cells to synthesize antiviral proteins (AVPs).

4. AVPs degrade viral mRNA and inhibit protein synthesis- and thus interfere with viral replication.

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Eustress

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- beneficial stress; appropriate in degree and duration; produces optimum physical and mental function and resistance to pathogens.

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Distress

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- harmful stress; excessive in degree and/or duration; impairs physical and mental function; reduces resistance to pathogens

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Role of skin and mucuous membrane in innate immunity

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1. Skin: The periodic shedding of the top layer helps remove microbes at the surface. Dryness of the skin inhibits microbial frowth on the skin. Microbes rarely penetrate the intact surface of healthy epidermis.

2. Mucous Membranes: line the entire gastrointestinal, respiratory, and genitourinary tract

- secretion of mucus

Front 12

Differentiate physical from chemical factors, and list 5 examples of each.

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Physical Factors: barriers to entry and processes that remove microbes from the body's surface.

ie. Lacrimal Apparatus, Ciliary Escalator, Vaginal Secretions, Urine Flow, Peristalsis, Defecation, Vomiting, and Diarrhea

Chemical Factors:

ie. Perspiration, sebum (oily substance), Earwax, Saliva, Gastric Juice

Front 13

Describe the role of normal microbiota in innate immunity.

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Normal microbiota prevent pathogens from colonizing the hsot by competing with them for nutrients (competitive exclusion), by producing substances that are harmful to the pathogens, and by altering conditions that affect the survival of pathogens (ie. pH).

Front 14

Classify the leukocytes and know their functions (Table 16.1 and Figure 16.4)

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1. Granulocytes:

Neutrophils: Phagocytosis

Basophils: Production of histamine

Eosinophils: Production of toxic proteins against certain parasites; some phagocytosis

2. Agranulocytes:

Monocytes: Phagocytosis

Dendrittic cells: Phagocyosis and initiation of adaptive immune responses

Lymphocytes:

Natural Killer Cells: Destroy target cells by cytolysis and apoptosis

T cells: Cell-mediated Immunity

B Cells: produce antibodies

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Lymphatic System

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consists of a fluid called lymph, vessels called lymphatic vessels, a number of structures and organ containing lymphoid tissure, and red bone marrow, where stem cells develop into blood cells. They protect against microbes that are ingested or inhaled.

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Blood Circulatory System

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k

Front 17

Why do Lymph nodes swell during an infection?

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During an infection, lymphocytes multiply profusely in lymph nodes. This proliferation and swelling cause lymph nodes to enlarge.

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What is the function of lymph nodes?

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- protect against microbes that are ingested or inhaled

to facilitate interactions among immune cells and between immune cells and material in the lymph arriving throughout the body

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Phagocytosis

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- the ingestion of particles by eukaryotic cells

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Phagocyte

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- a cell capable of engulfing and digesting particles that are harmful to the body

- all are types of white blood cells or white blood cell derivatives

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Mechanism of Phagocytosis (Fig 16.8)

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1. Chemotaxis and Adherence of phagocytes to microbe

2. Ingestion of microbe by phagocyte

3. Formation of phagosome (phagocytic vesicle)

4. Fusion of phagosome with a lysome to for ma phagolysosome

5. Digestion of ingested microbes by enzymes in the phagolysosome

6. Formation of the residual body containing indigestible material

7. Discharge of waste materials

Front 22

Identify 3 mechanisms of avoiding destruction by phagocytosis

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1. M protein

2. Capsules

3. Biofilms

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Stages of Inflammation (fig 16.9)

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1. Damage to otherwise healthy tissue

2. Vasodilation and increased permeability of blood vessels allows phagocytes migration. Phagocytosis by macrophages and neutrophils removes bacteria and cellular debris. Macrophages develop from monocytes.

3. The repair of damaged tissue.

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Phagocyte Migration

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Phagocytes begin to stick to the inner surface of the endothelium of blood vessels called margination. Collected phatocytes begin to squeeze between the endothelial cells of the blood vessel to reach the damaged area. This migration is called diapedesis. The phagocytes then begin to destroy invading microorganisms by phatocytosis.

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What purpose does inflammation serve?

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- confines and destroys microbes and initiates tissue repair

Front 26

Describe the cause and effects of fever

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Fever: an abnormally high body temperature (second line of defense)

Cause: Most frequent cause - infection from bacteria (and their toxins) or viruses

Effect: Body responds by constricting blood vesssels, increasing the rate of metabolism, and shivering all of which raises body temperature. The body will continue to maintain it's new temperature until cytokines are eliminated.

Body temp rises, but skin remains cold = chill (a definite sign that body temp is rising). When cytokines are eliminated, person begins to sweat (crisis) indicating the fall of body temp.

Tachycardia, increasesd metabolic rate, acidosis, dehydration, electrolyte imbalances, seizures in young children, delirium, coma, death.

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Three Consequences of Complement Activation, Opsonization, Inflammation and Cytolysis (Fig 16.12)

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Cytolysis: Microbes burst as extracellular fluid flows in through tansmembrane channel formed by membrane attack complex.

Opsonization: Coating microbes with C3b enhances phagocytosis.

Infammation: Blood vessels become more permeable, and chemotactic agents attract phagocytes to area.

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What is the role of siderophores in infection?

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Siderophores: compete to takke away iron from iron-binding proteins by binding it more tightly.

Iron-siderophore complex formed and split iron to be utilized.

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Why are sceintists interested in AMPs (antimicrobial peptides) ?

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- inhibit cell wall synthesis, form pores in the plasma membrane that cause lysis; and destroy DNA and RNA.

- have a broad spectrum of antimicrobial activities. synergy with other antimicrobial agents, microbes do not develop resistance to AMPs, can recruit mast cells

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Table 16.2 will be very helpful in summarizing the first and second lines of defense.

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First Line:

Physical: Epidermis, Mucuous membranes, Mucus, Lacrimal apparatus, Saliva, Hair, Cilia, Epiglottis

Chemical: Sebum, Earwax, Perspiration, Saliva

Second Line:

Defensive Cells, Inflammation. Fever

Front 31

First-Line Defenses

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First-line defenses keep pathogens on the outside or neutralize them before injection begins. The skin, mucuous membranes, and certain antimicrobial substances are part of these defenses.

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Second-Line Defenses

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Second-line defenses slow or contain infections when first-line defenses fail. They include proteins that produce inflammation, fever that enhances cytokine activity, and phagocytes and NK cells, which attack and destroy cancer cells and virus-infected cells.