Microbiology Lecture Exam 3

1) physical barriers imposed by the body

2) nonspecific immune system

3) specific immune system

true

1) epithelial cells

2) connective tissue

1) peristalsis

2) urine flow

3) ciliated cells on the trachea

1) Lysozyme (found in tears): degrades PTG

2) Peroxidase: Breaks down hydrogen peroxide to produce destructive oxidizing compounds

3) Lactoferrin: sequesters iron from iron-needing microorganisms

4) Defensins: antimicrobial peptides that form pores in microbial membranes

TRUE

TRUE

Generic term for blood cell formation (both red and white).

Occurs in the bone marrow.

Stem cell=a precursor cell that can differentiate into other cells.

ex: hematopoietic cells

a protein that regulates the immune response by binding to surface receptors and changing cell function.

A group of cytokines that when released, will tell the stem cell what path to go down/what cell to differentiate into, depending on which cytokine was released.

A stem cell that has committed to become a certain kind of cell.

1) granulocytes

2) Dendritic cells

3) mononuclear phagocytes

4) lymphocytes

1) neutrophils (most common)

2) basophils

3) eosinophils

Neutrophils are the "marines" of the immune system since they're the first to colonize a wound site.

2 functions:

1) phagocytosis of foreign cells

2) killing zone production=neutrophil is attracted to a site via cyotokines where it absorbs tons of O2 to make deadly hydrogen peroxide, which it releases, killing everything in the surrounding area (itself included)

Involved in the allergic reaction--> induce inflammation via histamine and heprin.

Histamine: vasodilator

heprin: anticoagulant

Involved in allergic reactions and in defense against parasitic worms.

2 functions:

1) release chemicals to kill parasitic worms

2) Deppresses the allergic response when necessary to prevent anaphylactic shock.

Monocytes are immune cells that circulate in the blood. They develop into/are called macrophages once they leave the blood stream, which can be fixed or wandering.

Scouts that sit in connective tissue and will digest foreign material before showing it to the specific immune system to help mount a specific immune response.

Detects a host cell that's infected with a virus and releases cytokines that cause the host cell to commit apoptosis (programmed cell death).

1) B cells: make antibodies (immune proteins)

2) (Helper) T cells: either produce cytokines to signal the appropriate response from the rest of the body, or help B cells make antibodies.

any substance that elicits an immune response from the body.

Scratches the skin and exposes it to TB antigens. if the body reacts, it means you've been exposed to someone with TB.

-However, someone who's been vaccinated against TB will always produce a positive result from the TB test.

programmed cell death. Induced by either T cells or Natural Killer cells.

1) Cell surface receptors are the "eyes" and "ears" of the cell.

2) Cytokines are the "voice"

3) Adhesion molecules are the "hands"

-As neutrophils pass by in the blood stream, they bind to CAM on the endothelial cells and roll along the cell until they find a junction they can squeeze through to get to the infection/damage site.

1) Chemokines: enhance ability of cells to migrate to appropriate body site.

2) Interleukins: important in innate and adaptive immunity

3) Tumor necrosis factor: instrumental in initiation of inflammation and apoptosis.

1) Toll like receptors (TLR): on the outside of the cell

2) NOD proteins: found on the inside of the cell

TLRs and NOD proteins in the sensor system look for patterns of chemicals (LPS, PTG, etc) that are foreign and should NOT be there. They react to things that reflect the idea that pathogens are in the body and trigger the cell that carries these pathogens to an immune response.

-A series of 9 normally inactive proteins (C1-C9) circulating in the blood that, when activated by pathogens, set off a cascade of reactions that activate other complement proteins.

-Part of the innate (nonspecific) immune system, but it enhances the actions of the adaptive immune system too.

1) Inflammation: C3a and C5a involved

2) Opsonization: when a host molecule tags/binds to foreign material to allow phagocytes to more easily engulf it.

Performed by C3b

3) Lysis of foreign cells

-antibodies

-C3b

-mannan-binding lectins

1) Classical Pathway

2) Lectin pathway

3) Alternate Pathway

An antibody binding to a microbial surface activates other complement proteins.

The binding of complement protein C3b to a microbial cell surface initiates the activation of other complement proteins (C3b is always circulating in the blood at low levels)

Activation of lysis thru this pathway requires mannan-binding lectins (MBL)

-Binding of MBL to microbial surface activates other complement proteins.

a protein channel structure formed on the surface of pathogenic bacterial cells as a result of activation of one of the 3 lysis pathways of the complement system.

1) rubor (redness)

2) calor (warmth)

3) tumor (swelling)

4) dolor (pain)

because many different pathogens can induce it and it can combat many different kinds of pathogens.

1) mast cells found in the wound site release chemical mediators

2) neutrophils come out of blood vessels and form necrotic tissue, followed by white blood cells

3) pus forms

4) macrophages clear the area

1) attracts immune components to the site of injury

2) set in motion mechanisms to repair tissue

3) destroy microbes and block further invasion

4) dilutes toxic substances

5) fibrin (a protein) can trap microbes and prevent further spreading

Part of the innate immune system, it eats pathogens and presents them to T cells so that they know how to respond with the specific immune system.

1) presents it to a Helper T cell --> Helper T cell proliferates and activates macrophages that engulfed the antigens recognized by the T cell.

2) Presents it to a Helper T cell --> TH cell proliferates and then activates B cells that bind the antigen recognized by the TH cell --> proliferation of B cell --> plasma cell --> antibody production --> antibodies bind antigen.

3) Presents it to a Helper T cell --> TH cell proliferates and then stimulates Cytotoxic T cells that bind antigen --> Tc cells induce apoptosis in infected host cells.

4) Presents it directly to a Cytotoxic T cell --> Tc cell proliferates and then induces apoptosis in infected host cells

it's responsible for coordinating the specific immune response. Specific to the cells they affect. Can potentially:

-activate macrophages

-stimulate cytotoxic T cells

1) B cells: start and develop in the bone marrow.

2) T cells: start in the bone marrow but leave while immature to finish developing in the thymus.

Antibodies are Y-shaped proteins that stick to antigens on the surface of germs, creating clumps that alert your body to the presence of intruders that can then be destroyed. With the help of T cells, they are produced exclusively by B cells.

-Memory B-cells: produced in smaller numbers, they stay in the body for a long time to increase the number of this clone and retain a memory of the antigen in question for the future.

-Plasma B-cells: short-lived cells that fight and produce more antibodies.

1) B cell processes the antigen and displays it with MHCII

2) MHCII w/ attached antigen on surface of B cell forms a complex to TCR protein found on surface of passing helper T cell.

3) union of TCR and MHCII leads to Helper T cell secreting the cytokine IL-4 toward the B cell that tells it to proliferate.

4) B cell reproduces and forms a large number of plasma B cell clones as well as a smaller number of Memory B cell clones. Plasma cells synthesize and secrete antibody.

They bind pathogen-derived peptide fragments and display them on the surface of their cell for recognition by the appropriate T cell. So, they're basically the things that cells complex antigens with to display said antigens.

Possessed by:

-B cells (complexes antigen with MHC class II)

-Dendritic cells (complexes antigen with MHC class I and II)

-Macrophages (complexes antigen with MHC class II)

1) phagocytosis of antigen

2) lysosome fuses with phagosome

3) antigen and enzyme mix in phagolysosome

4) antigen is degraded

5) antigen fragments displayed on macrophage surface via MHC protein

It's when donor/grafted bone marrow attacks the host body (Since the immune system comes from bone marrow).

Avoid it by irradiating all host bone marrow of hemopoietic cells before grafting donor bone marrow.

1) IgG: long-term immunity; makes memory antibodies; neutralizes toxins, opsonizes, fixes complement.

2) IgA: found in sweat, breast milk, colostrum (mucous membranes)

3) IgM: produced at first response to antigen; can serve as B-cell receptor.

4) IgD: receptor on B cells

5) IgE: antibody of allergy and worm infections.

TRUE

It changes the function and location of the B cell; however, it still recognizes the SAME antigen!

When self-recognizing clones of lymphocytes are eliminated to prevent an autoimmune response.

A way to measure antibody production

The immune response that's mediated by antibody molecules secreted by plasma cells.

Slow at first during the first encounter with an antigen (primary response) because it takes time for the naive B cell to encounter the antigen and then for the Helper T cell to find the B cell.

1) neutralization: binding of antibodies to viral receptors is enough to render them useless in some cases.

2) agglutination: antibodies form complex with bacterial cells that trigger phagocytosis in any passing macrophage.

3) precipitation: antibodies "tie together" small antigen molecules (as opposed to big bacterial cells) that trigger phagocytosis in any passing macrophage.

4) Opsonization (leads to bacteria being engulfed more readily)

5) Complement fixation: can lead to either increased opsonization, lysis or inflammation.

Passive immunity is only temporary (maybe a few weeks) and must be renewed (ex: by continually breastfeeding)

1) Natural active: infection thru contact with pathogen and then getting better; produces the best immunity (if you don't die first)

2) natural passive: antibodies pass from mother to fetus via placenta and then from mom to baby during breastfeeding.

3) Artificial active: Vaccine

4) Artificial passive: injection of immune serum (preformed antibodies); used for snake bites.

MHC class I; MHC class II

Helper T cells become activated to divide rapidly and secrete small proteins called cytokines that regulate or assist in the active immune response. Cytotoxic T cells(TC cells, or CTLs) destroy virally infected cells and tumor cells, and are also implicated in transplant rejection.