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Unit 4
Ch. 15, 16, 17, 18, 19
69
Microbiology
Undergraduate 2
06/21/2011

Additional Microbiology Flashcards

 


 

Cards

Term
Portals of Entry for Microbial Infection
Definition
Respiratory Tract
Genitourinary Tract (GU)
Gastrointestinal (GI)
Skin
Parenteral Route (Insect Bites)
Placenta
Term
Invasiveness
Definition
The ability of a microbe to colonize the tissues of a host.

Some bacteria have structural components which act as adhesions/ligands and bind to receptors on host cells- can form biofilms
Examples:
Capsule- Streptococcus mutans
Fimbriae- Escherichia coli
M Protein (wall)- Streptococcus pyogenes
Opa protein (wall)- Neisseria gonorrhoeae
Mycolic acid (wall)- Mycobacterium tuburculosis
A protein (wall)- A protein which binds antiodies by stem region- Staphococcus aureus

Some bacteria use structural components to protect themselves from phagocytosis:
Capsules & Cell Wall Proteins
Term
Toxicity
Definition
The ability of a microbe to produce a harmful substance such as an exotoxin or endotoxin.
Term
Capsules
Definition
Prevent phagocytosis
-Streptococcus pneumoniae
-Haemophilus influenzae
-Bacillus anthracis
Term
Cell Wall Components
Definition
M Protein- resists phagocytosis (streptococcus pyogenes)

Opa protein- inhibits T helper cells (Neisseria gonorrhoeae)

Mycolic acid (waxy lipid)- resists digestion (Mycobacterium tuberculosis)

A protein- Staph. aureus has a protein associated with the wall; "A-protein" which binds antibodies by the stem region.
Term
Toxin
Definition
Substance that contributes to pathogenicity.
Term
Toxigenicity
Definition
Ability to produce a toxin
Term
Toxemia
Definition
Presence of toxin in the host's blood.
Term
Toxoid
Definition
Inactivated toxin used in a vaccine.
Term
Antitoxin
Definition
Antibodies against a specific toxin
Term
Membrane-Disrupting Toxins
Definition
Lyse host's cells by-

1. Making protein channels in the plasma membrane (leukocidins, hemolysins (alph & beta), streptolysins

2. Disrupting phospholipid bilayer.
Term
Superantigens
Definition
Cause an intense immune response due to release of cytokines from host cells.

Symptoms: fever, nausea, vomiting, diarrhea, shock and death
Term
Endotoxins and the Pyrogenic Response
Definition
1. A macrophage ingests a gram-negative bacterium.
2. The bacterium is degraded in a vacuole, releasing endotoxins that induce the macrophage to produce cytokines IL-1 & TNF-alpha
3. The cytokines are released into the bloodstream by the macrophages, through which they travel to the hypothalamus of the brain.
4. The cytokines induce the hypothalamus to produce prostaglandins, which reset the body's "thermostat" to a higher temp, producing fever.
Term
Enzymes Produced as Virulance Factors
Definition
Hyaluronidase, Kinases, Coagulases, Collagenase, Ig-A proteases, Keritinase
Term
Hyaluronidase
Definition
called the "spreading factor"- breaks down hyaluronic acid, a tissue "cement" found particularly in connective tissue
Term
Kinases
Definition
enzymes that dissolve fibrin clots formed in tissue in response to trauma allowing organisms to invade
Term
Coagulases
Definition
enzymes that initiate clot formation (fibinogen->fibrin) in plasma walls off organisms and prevents phagocytosis. (Staph. aureus)
Term
Collagenase
Definition
an enzyme which breaks down collagen, a binding protein found in connective tissue throughout the body. (Gang green)
Term
Ig-A Proteases
Definition
destroy IgA (mucosal antibody) antibodies
Term
Keratinase
Definition
digest keratin- protein found in skin and nails
Term
Exotoxins
Definition
Proteins produced inside pathogenic bacteria, most commonly G+ bacteria, as part of their growth & metabolism. They are then secreted or released into the surrounding medium following lysis.

Heat sensitive; strongly anitigenic (immunize w/taxoid); can be classified by action; highly toxic.

A-B (diptheria & botulism)- inhibit protein synthesis)
Membrane Disruption- Hemolysins & Leukocidins
Superantigens- Staph. enterotoxin (in gut)

Symptoms: fever, cardiovascular disturbances, diarrhea & shock. (vary by which type)
Term
Endotoxins
Definition
The lipid portions of lipopolysaccharides (LPSs) that are part of the outer membrane of the cell wall of G- (Lipid A). They are liberated when the bacteria die and the cell wall breaks apart during lysis. Stimulate macrophages to release cytokines in very high, toxic concentrations.
Heat resistent; non-specific generalized action; weak antigen (antibodies are nonprotective, therefor, no toxoid); no antitoxin, but drug "Zovan" counteracts clotting & inflammation
Responsible for meningococcal meningitis & typhoid fever

Symptoms: chills, fever, weakness, generalized aches & in some cases, shock & death. Can also induce miscarriages.
Term
Innate Immunity
Definition
immunity that is present at birth.
Term
First line of defense
Definition
Intact skin
Mucous membranes and their secretions
Normal Microbiota
Term
Second line of defense
Definition
Phagocytes, such as neutrophils, eosinophils, dendritic cells and macrophages

Inflammation

Fever

Antimicrobial substances
Term
Adaptive Immunity (3rd line of defense)
Definition
Specialized lymphocytes: T cells & B cells

Antibodies
Term
Cytokines
Definition
proteins that regulate the intensity and duration of immune responses; recruit other macrophages & dendritic cells to isolate & destroy microbes as part of the inflammatory response; also activate T cells & B cells in adaptive immunity
Term
Innate Immunity (function)
Definition
Toll-like receptors (TLRs) attach to Pathogen-associated Molecular Patterns (PAMPs) and induce cytokines that regulate the intensity & duration of the immune response.
Term
Mechanical Defenses in Innate Immunity
Definition
Skin- epithelial barrier, keratin
Respiratory Tract- epithelial barrier; mucous membrane; cilia; haris in nares; coughing; sneezing
Gastrointestinal Tract- epithelial layer' mucous membranes; peristalsis (smooth muscle contraction)
Genitourinary Tract- epithelial barrier; mucous membranes; urine flow; length of urethra & ureters; cervical barrier; vaginal secretions
Term
Chemical Defenses in Innate Immunity
Definition
Skin- fatty acids in sebum; low pH; low moisture; high salt; lysozome; interferons
Respiratory Tract- lysozome; salt in tears; interferons
Gastrointestinal Tract- low pH; bile salts; gastric juices; lysozome; interferons
Genitourinary Tract- low pH; interferons
Term
Cellular Defense Mechanisms
Definition
Phagocytosis

Normal Microbiota

Inflammation

Fever

Interferons
Term
Phagocytosis
Definition
the ingestion of a microorganism or substance (such as debris) by a cell.

Process:
chemotaxis (chemical attraction)->Ingestion of microbe by phagocyte->Digestion of ingested microbe by enzymes (lysosome)-> Discharge of waste materials
Term
Inflammation
Definition
Function- Destruction of pathogen, confinement of injured area, repair of injured tissue

Triggers- injury to host tissue

Responsible Cells- basophils, mast cells & platelets

Signs: redness, swelling, pain, heat

Stages: vasodilation & increased permeability in blood vessels; phagocyte migration & phagocytosis; repair

Chemicals released: Histamine, Kinins, Prostaglandins, Leukotrienes
Term
Fever
Definition
ADVANTAGES:

Increases transferrins, decreasing iron available to microbes

Increases IL-1 activity, thus increasing T-cell production

Intensifies Interferon

Increases metabolic rate which may help w/body reactions or hurt w/acidosis

Slows growth of some pathogens, but will NOT kill bacteria

DISADVANTAGES:

Tachycardia
Acidosis (metabolizing fat instead of sugar)
Dehydration
44-46 degrees is fatal
Term
Interferons
Definition
Proteins produced in small amounts by specific host cells (host specific, not virus specific).

Types- Alpha, Beta & Gamma

"Paul Revere" cytokines that warn that a virus is present. Newly warned neighbor cell then produces anti-viral proteins (AVPs) which interfere with viral replication.
Term
Complement System
Definition
defensive system consisting of over 30 serum proteins found in normal serums.
Term
What activates the 3 compliment pathways?
Definition
1. Antigen Antibody Complex
2. Chemical complexes on the surface of foreign cells.
3. Lectins- proteins produced by the liver
Term
What are the actions of complement?
Definition
1. Opsonization or immune adherence (enhanced phagocytosis)
2. Membrane attack complex (cytolysis)
3. Attract phagocytes (Stimulate inflammation)
Term
Neutrophils
Definition
Phagocytosis

(70% of white blood cells)
Term
Basophils
Definition
(mast cells) Produce inflammatory chemicals: histamine, leucotrienes, prostaglandins
Term
Eosinophils
Definition
Produces toxic proteins against certain parasites, some phagocytosis

Numbers increase during an allergic response.
Term
Dendritic Cells
Definition
Derived from monocytes; phagocytosis and initiation of adaptive immune response-
APC (anitgen presenting cells)
Term
Monocytes
Definition
phagocytic as mature microphages- APC
Term
Lymphocytes
Definition
NK (natural killer cells)- Lymphocite cells without T or B cell markers that are NOT antigen specific. They have receptors for the Fc region of IgG antibodies. When they detect a cell with numerous IgG antibodies attached they attack it in the manner of the CD_8 cytotoxic cell using perforin and proteases to induce apoptosis. This is called antibody-dependent cell mediated cytotoxicity (ADCC). This is usefull in controlling large parasites too large to be engulfed by phagocytic cells.

Involved in adaptive immunity.
Term
Chemicals Released by damaged cells
Definition
Histamine- vasodilation, increased permeability of blood vessels

Kinins- Vasodilation, increased permeability of blood vessels

Prostaglandins- Intensity histamine and kinin effect

Leukotrienes- Increased permeability of blood vessels, phagocytic attachment
Term
Opsonization
Definition
The enhancement of phagocytosis by coating microorganisms with certain serum proteins (opsonins); also called immune adherence
Term
IgM
Definition
1st responder; pentamer
Term
IgA
Definition
in secretions; dimer
Term
IgE
Definition
allergic reactions; worms
Term
IgG
Definition
80% of serum antibodies; able to cross placenta & found in breast milk
Term
T cells
Definition
Cell-mediated immunity
Term
B cells
Definition
Descendents of B cells (plasma cells)- produce antibodies
Term
T-lymphocytes
Definition
mature in thymus; can be divided into 2 major subsets- CD4+ (helpers) & CD8+(cytotoxic)
Term
CD-4 cells
Definition
also known as TH or T-helper cells; once activated by antigen exposure they differentiate into 2 populations- TH-1s & TH-2s.
Term
TH-1
Definition
produce cytokines that activate macrophages, stimulate production of antibodies that promote phagocytosis & enhance complement; activates eosinophils.
Term
TH-2
Definition
produce cytokines that are primarily associated with antibody production, especially IgM & IgE; activates eosinophils.
Term
CD-8 cells
Definition
activated by dendritic cells & TH-1 cells to become CTLs (cytotoxic T lymphocyte), which release cytotoxins such as perforin and proteases. Perforin facilitates penetration of proteases called granzymes which induce apoptosis in the target cell- an abnormal host cell causing its death by minimizing inflammation or spread of a virus to other cells.
Term
T-regulatory cells
Definition
appear to suppress other T-cells, secrete IL-10 and regulate the immune response. They combat autoimmunity and protect the intestinal bacteria from the immune system. They are a subset of the CD-4 cells and also carry the CD-25 marker.
Term
Superantigens
Definition
relatively nonspecific antigens that indiscriminately activate many T-cell receptors at once, producing a response harmful to the host. Examples of such antigens are the enterotoxins of Staphylococcus aureus and the toxin of toxic shock syndrome.
Term
Cytokines
Definition
a small protein released from human cells that regulates the immune response; directly or indirectly may induce fever, pain or T-cell proliferation.
Term
Lysosome
Definition
an organelle containing digestive enzymes
Term
Active Immunity
Definition
when a person is exposed to microorganisms or foreign substances and the immune system responds.
Term
Passive Immunity
Definition
when antibodies are transferred from one person to another. Only lasts as long as the antibodies are present- in most cases, a few weeks.
Term
Antiserum
Definition
A blood-derived fluid containing antibodies.
Term
M (microfold) cells
Definition
Intestinal cells that take up and transfer antigens to lymphocytes.
Term
Haptens
Definition
A substance of low molecular weight that does not cause the formation of antibodies by itself, but does so when combined with a carrier molecule.
Term
Clonal Selection
Definition
The development of clones B and T cells against a specific antigen.
Term
Apoptosis
Definition
The natural programmed death of a cell; the residual fragments are disposed of by phagocytosis.
Term
Hypersensitivity
Definition
An altered, enhanced immune reaction leading to pathological changes; also called allergy
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