Chapter 22: Immune System and the Body's Defense

Cardinal signs of inflammation

1) REDNESS- due to increased blood flow 2) HEAT- due to increased blood flow and increased metabolic activity in area 3) SWELLING- due to increase in fluid loss from capillaries to interstitial space 4) PAIN- due to stimulation of pain receptors from compression due to accumulation of interstitial fluid and chemical irritation by kinins, prostaglandins, and substances released by microbes 5) LOSS OF FUNCTION- may occur in more severe cases due to pain and swelling

Structures that house immune cells

1) lymphatic tissue 2) select organs 3) epithelial layers of the skin and mucosal mebranes 4) connective tissues -most leukocytes are found in body tissues

stages of a fever

1) onset 2) stadium 3) defervescence -can be cyclical until pathogen is eliminated or brought under control

steps of inflammation

1) release of various chemicals 2) vascular changes 3) recruitment of leukocytes 4) delivery of plasma proteins

epitope

--Each type of antigenic determinant has a different shape, and a --pathogenic organism can have numerous different antigenic determinants

Fever (benefits)

-Increased activity of interferons and adaptive immunity. -Decrease in bacterial and viral replication

Processes of 2nd line of defense

-Inflammation -Fever

Chemicals in 2nd line of defense

-Interferons -Complement

Cells in 2nd line of defense

-Neutrophils and macophages -Basophils and mast cells -NK cells -Eosinophils

Fever (causes)

-The hypothalamus increases set point for temperature. -The hypothalamus stimulates vasoconstriction in dermis. -Shivering

fever

-abnormal elevation in body temperature (pyrexia) of at least 1 degree C (1.8 degree F) from typically accepted core temperature of 37 degree C (98.6 degrees F)

Complement System

-at least 30 plasma proteins that make up ~10% of blood serum proteins -collectively referred to as complement -"complement" or work along with antibodies -identified with C followed by number (ex: C1, C2) -inactive complement proteins continuously synthesized and released by liver into blood -activated by enzyme cascade once in blood -mediates several important defense mechanisms, especially potent against bacterial infections

how do innate immune system cells recognize foreign cells?

-because the immune system cells posses pattern recognition receptors on their surface -these receptors bind to common molecular patterns (motifs) of microbes, including those of bacteria and viruses -TLRs = toll-like receptors, family of receptors, with each class recognizing a specific microbial component

opsonization

-binding of protein (ex: complement) to portion of bacteria or other cell type that enhances phagocytosis -opsonin = binding protein -binding of complement increases likelihood that substance is identified and engulfed by phagocytic cell (ex: macrophage) -complement OPtimizes phagocytosis

Cytosis Categories

-categories: interleukin (IL), tumor necrosis factor (TNF), colony-stimulating factor (CSF), interferon (IFN

inflammation

-complement increase inflammatory response through activation of mast cells and basophils and by attracting neutrophils and macrophages, complement activates and attracts cells of innate immunity

classical pathway

-complement protein binds to an antibody that has previously attached to a foreign substance (ex: portion of bacterium) -antibody required

dendritic cells after phagocytosis

-destroy infectious agents and then present fragments of microbe on cell surface to T-lymphocytes = antigen presentation -necessary for initiating adaptive immunity -antigen presentation shared with macrophages

neutrophils and macrophages after phagocytosis

-destroy infectious agents through process involving lysosome and respiratory burst -phagosome merges with lysosome to produce a phagolysosome -reactive oxygen-containing molecules are produced to facilitate destruction of microbes and viruses (nitrous oxide, hydrogen peroxide, superoxide)

onset

-hypothalamus stimulates blood vessels in dermis of skin to vasoconstrict -decreases heat loss through skin -person shivers to increase heat production through muscle contraction -body temperature rises -may experience chills leading to shivering

benefits of fever

-inhibits replication of bacteria and viruses -promotes interferon activity -increases activity of adaptive immunity -accelerates tissue repair -increases CAMs on endothelium of capillaries in lymph nodes, results in additional immune cells migrating out of blood into lymphatic tissue

adaptive immunity

-initiated upon entry of foreign substance or antigen -takes longer to response than innate immunity -contact with antigen causes lymphocyte proliferation and differentiation to form specialized clones or army of lymphocytes against the pathogen

chemotaxis

-migration of cells along a chemical gradient -chemicals from damaged cells, dead cells, or invading pathogens diffuse outward and form a chemical gradient that attracts immune cells -recruited cells participate in inflammatory response through release of specific cytokines that stimulate leukopoiesis in red bone marrow (

activation of a complement

-occurs following entry of pathogen into body -classical pathway and alternative pathway

cytotoxic chemicals

-perforin- forms transmembrane pore in unwanted cells -granzymes- enter cell through transmembrane pore initiating apoptosis

stadium

-period of time where the elevated temperature is maintained -metabolic rate increases to promote physiologic processes involved in eliminating the harmful substance -liver and spleen bind zinc and iron (minerals needed by microbes) to slow microbial reproduction

diapedisis

-process by which cells exit blood by squeezing between vessel wall cells and then migrate to site of infection -usually in postcapillary venules

immune surveillance

-process in which NK cells patrol the body in an effort to detect unhealthy cells -make physical contact with cells and destory them by release of cytotoxic chemicals

basophils and mast cells

-proinflammatory chemical-secreting cells -basophils circulate in blood -mast cells reside in connective tissue of skin, mucosal linings, and various internal organs -secreted substances increase fluid movement from blood to injured tissue -serve as chemotactic chemicals, attract immune cells as part of inflammatory response -release granules during inflammatory response, granules contain various substances including histamine and heparin -also release eicosanoids from plasma membrane that increase inflammation

alternative pathway

-surface polysaccharides of certain bacterial and fungal cell walls bind directly with complement protein -antibody not required

cytolysis

-various complement components trigger direct killing of a target by forming protein channel in plasma membrane of a target cell called a membrane attack complex (MAC) -channel compromises cell's integrity, allows an influx of fluid that causes lysis of cell

defervescence

-when temperature returns to its normal set point -hyothalamus no longer stimulated by pyrogens, prostaglandin release decreases, temperature set point reverts to normal value -hypothalamus stimulates mechanisms to release heat from the body, vasodilation of blood vessels in skin and sweating -person may appear flushed and skin warm to touch -increase in fluid intake should occur during fever to prevent dehydration caused by increased loss of body fluid

What are the five classes of immunoglobulins?

IgG, IgM, IgA, IgD, and IgE

innate immunity

Immediate response to wide array of substances. --The immunity we're born with.

fungi

Multicellular eukaryotes, perform extracellular digestion and induce inflammation. Ex: ringworm, athletes foot, yeast infection

parasites

Multicellular eukaryotes, take nourishment. Ex: roundworm, tapeworm (helminthosis)

Define antibody-dependent cell-mediated cytotoxicity.

NK cells destroy abnormal cells by the release of cytotoxic chemicals that cause apoptosis of the cell

second line of defense (still innate immunity)

Nonspecific internal defenses -- cells, chemicals, physiologic responses. --Works with adaptive immunity

Virus

Nucleic Acid within a capsid (protein coat) Ex: cold, HIV, warts, chicken pox

Eosinophils`

Parasite-destroying cells.

basophils and mast cells

Proinflammatory chemical-secreting cells -Enhance inflammation

Interferon

Proteins produced by infected cells -- they interfere with the ability of viruses to replicate in the body and spread. -stimulate NK cells -source: leukocytes, fibroblasts -IFN followed by greek letter, ex: IFN-alpha

Complement

Refers to more than 30 proteins in the body. -Opsonization -Inflammation -Cytolysis -Elimination of immune complexes

Cytosis Effects

Signaling cells (including non-immune cells, e.g., neurons) Controlling development and behavior of immune cells Regulating inflammation response

first line of defense

Skin and mucosal membranes -- prevent entry.

Positive Selection

Survival dependent upon ability to bind to MHC molecule. -Thymic epithelial cell presents MHC to pre-T-lymphocyte.

Negative Selection

Survival dependent upon not recognizing self-antigen. -Dendritic cell presents self-antigen to pre-T-lymphocyte.

The maturation of __________________ involves positive & negative selection.

T Lymphocytes

Cell mediated Immunity

T-lymphocyctes -Effective against antigen within cells -Requires antigen-presenting cell

What is an antibody titer?

The circulating blood concentration of antibody against a specific antigen

the effector response

The effector response comprises the specific mechanisms that activated lymphocytes use to help eliminate the antigen.

antigenic determinant

The specific site on the antigen molecule that is recognized by components of the immune system

? Describe the shape and structure of an immunoglobulin

The structure of an antibody is a Y-shaped protein that includes two variable regions that bind antigen and one constant region that determines its biological activity. soluble protein composed of four polypeptide chains: two identical heavy chains and two identical light chains with flexibility at the hinge region of the two heavy chains.

Describe MHC proteins. What are the two classes and how do they differ?

This name refers to the group of genes that code for MHC molecules embedded within plasma membranes. There are two primary categories of MHC molecules: MHC class I molecules and MHC class II

protozoans

Unicellular eukaryotes, intra/extra cellular parasites in order to obtain nutrients. Ex: malaria (intra) giardiasis (extra)

bacteria

Unicellular prokaryotes, require nutrients to survive. Destroying tissues or releasing toxins. Ex: staph, lyme, tuberculosis

where are the variable and constant of an antibody and what is their function?

Variable -- located at the ends of the "arms" of the antibody contain the antigen-binding site The variable region binds the antigen through weak intermolecular forces Constant - constant region contains the Fc region, which is the portion of the antibody that determines the biological functions of the antibody. It located same or nearly the same in structure for antibody molecules of a given class;"

antigen (immunoglobin)

a substance capable of provoking an immune response when introduced into an immunocompetent hose to whom it is foreign

What is the function of activated memory helper T-lymphocytes?

activated helper T-lymphocytes that continue to produce IL-2, and some are memory helper T-lymphocytes, cells available for subsequent encounters with the specific antigen.

What are the two categories of cells that present antigens to T-lymphocytes (describe these types of cells or give examples).

all nucleated cells of the body (i.e., all cells except erythrocytes) and a category of cells called antigen-presenting cells.

heparin

anticoagulant

What type of lymphocyte communicates with this type of forgein MHC 1 cell

cytotoxic T-Lymphocytes

What are the ways cytotoxic T-lymphocytes destroy infected cells?

cytotoxic T-lymphocytes destroy abnormal cells through the release of the cytotoxic chemicals perforin and granzymes

If the pre-T-lymphocytes does not bind to a MHC molecule, it is...

destroyed by apoptosis

If the pre-T-lymphocytes recognizes self-antigen, it is...

destroyed by apoptosis

How do helper T-lymphocytes play a central role in the normal functioning of the immune system?

enhance formation and activity of cells of the innate immune system including macrophages and NK cells.

what are the different antibody classes and their roles?

gM - can fix complement; IgA - found mainly in mucus; IgD - important in activation of B cell; IgG - can cross the placental barrier; IgE - involved in allergies

know the two cell types a T-lymphocyte can differentiate into.

helper T-lymphocyte cytotoxic T-lymphocyte

immunogen and immunogenicity

immunogen--An antigen that induces an immune response immunogenicity -- immunogen ability to cause an immune response

histamine

increases vasodilation and capillary permeability

When is the effector response initiated?--cytotoxic T-lymphocytes

nitiated when physical contact is made between a cytotoxic T-lymphocyte and an unhealthy or foreign cell such as a virus-infected cell, bacteria-infected cell, tumor, etc.

examples of antigens

parts of infectious agents such as the protein capsid of viruses, cell wall of bacteria or fungi, and bacterial toxins. Tumor cells also contain antigens

What is an exogenous antigen? What type of lymphocyte communicates with this type of antigen?

pathogens, cellular debris, or other potentially harmful substances located outside of cells --helperT-lymphocytes.

Neutrophils and macrophages:

phagocyte cells

how does each of these work to help destroy an infected cell?

1. Complement fixation - activation of complement by the classical pathway. 2. Opsonization- (making it more likely that a target is "seen" by phagocytic cells). 3. Activation of NK cells-destroy abnormal cells by the release of cytotoxic chemicals

the actions of antibodies once an antigen (or complement protein) binds to the Fc region

1. Complement fixation. 2. Opsonization. 3. Activation of NK cells.

Describe the actions of antibodies once an antigen binds to the antigen-binding site

1. Neutralization occurs when an antibody covers the region of a virus used to bind to a cell receptor. 2. Agglutination. Antibody cross-links antigens of foreign cells, causing them to agglutinate or "clump." 3. Precipitation. Antibody can cross-link soluble, circulating antigens such as viral particles (not whole cells) to form an antigen-antibody complex. precipitated complexes are then engulfed and eliminated by phagocytic cells

inflammation

A tissue's response to injury and/or infection -- characterized by: cardinal signs of inflammation.

Prions

Abnormal proteins found in the brain (nervous tissue) Ex: mad cow disease

how are MHC classes different

All nucleated cells present antigen with MHC class I molecules

what are antibodies?

soluble proteins secreted by B cells (plasma cells) that aare capable of binding specifically to an antigen.

What are the effectors of B-lymphocytes. ? How are these formed

Antibodies are the effectors of humoral immunity. Antibodies are formed by plasma cells (although limited amounts are produced by B-lymphocytes)

what are 3 important aspects of immune response?

Antigen Specific, Systemic, Has Memory

antigen presentation definition

Antigen presentation is the display of antigen on a cell's plasma membrane surface. This is a necessary process performed by other cells so that T-lymphocytes can "see" an antigen.

hapten

substances too small to be recognized alone, but may stimulate the immune repsonse when complexed to larger carrier molecules --An example is the lipid toxin in poison ivy, which penetrates the skin and triggers an immune response after combining with a body protein examples, reactions to drughs, chemicals such as pollen, aminal dander, mold, snake or bee

NK cells

Apoptosis-intitiating cells -Cause other cells to die.

how does the humoral response work?

B lymphocytes remain immature until an antigen binds to it's surface making it a B-cell. The B-cell then creates a large number or clones. Most turn to plasma cells, but a few become long-lived memory cells.

Humoral Immunity (Antigen mediated)

B-lymphocytes -Effective against antigen outside cells; does not require antigen-presenting cell

costimulation

Both T-lymphocytes must undergo a first and second stimulation (costimulation) to become activated.

T Lymphocytes (adaptive)

Cell-mediated immunity

what is self tolerance?

the process by which cells learn to "ignore" molecules of the body or self-antigens

Cytokines

Cytokines: small proteins that regulate immune activity -Produced by cells of both innate and adaptive immune system -Chemical messengers released from one cell that bind to receptors of target cells

adaptive immunity

Delayed response to specific antigens. --3rd line of defense --Specificity and memory

Know with lymphocyte this virus targets.

HIV (the virus that causes AIDS) specifically targets the helper T-lymphocytes

Describe the effector responses of activated helper T-lymphocytes.

Help T release various cytokines

B Lymphocytes (adaptive)

Humoral immunity -- antibody-mediated --Plasma cells (synthesize and release antibodies)