microbiology test 4
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60 terms
Terms | Definitions |
|---|---|
 Pathology | study of disease |
| Etiology | cause of a disease |
| infection | colonization of the body by pathogens |
| disease | an abnormal state in which the body is not functioning normally |
| Normal Flora | permanently colonize the host |
| Transient Flora | may be present for days, weeks, or months |
| Microbial Antagonism | competition between microbes: |
| Herd immunity | immunity in most of a population |
| Predisposing Factors | make the body more susceptible to disease ex: gender - short urethra in females inherited traits - sickle cell gene climate, fatigue, age, lifestyle, immunosuppression |
| Reservoirs of Infection | **Human — AIDS, gonorrhea - Carriers may have inapparent infections or latent diseases **Animal — Rabies, Lyme disease - Some zoonoses (animal diseases) may be transmitted to humans **Nonliving — Botulism, Tetanus - Soil |
| Stages of a Disease |  |
| Systemic Infection | Infection throughout the whole body |
| Toxemia | Toxins in the blood |
| types of contact transmission | direct: requires close association between infected person and susceptible host indirect: spread by fomites (nonliving objects involved in spread of an infection) example: sheets, towels, doorknobs, toys droplet: transmission via airborne dorplets (<1 meter) |
| types of vehicle transmission | transmission by an inadequate reservoir -food, water, air and blood |
| types of vector transmission | mechanical feet - Arthropod carries pathogen on biological - Pathogen reproduces in arthropod vector |
| Sign | A change in a body that can be measured or observed as a result of disease (e.g. fever, swelling) |
| Symptom | A change in body function that is felt by a patient as a result of disease (e.g. tiredness, pain) |
| Syndrome | A specific group of signs and symptoms that accompany a disease. |
| Acute Disease | symptoms develop rapidly, usually short-lived |
| Chronic disease | disease develops slowly, longer-lasting |
| Nosocomial Disease | Are acquired as a result of a hospital stay *hand-washing is the most important means of preventing the spread of infection |
| portals of entry for a pathogen | -mucous membranes (respiratory tract, GI tract) -skin (hair follicles, sweat glands) -Parenteral route (deposited directly under skin - cuts, bites, injections, surgery) -preferred -multiple |
| ID 50: | Infectious dose for 50% of the test population; measures virulence |
| LD 50: | Lethal dose (of a toxin) for 50% of the test population |
| Coagulase | Coagulates blood (fibrinogen -> fibrin clots) |
| Kinases | Digest fibrin clots |
| Antigenic Variation | Alteration of cell-surface molecules to avoid host's immune system |
| Siderophores | Remove iron from host's iron-binding proteins |
| portals of exit for a pathogen | *Respiratory tract-Coughing, sneezing *Gastrointestinal tract-Feces, saliva *Genitourinary tract-Urine, vaginal secretions *Skin *Blood-Biting arthropods, syringe needles |
| host defenses |  |
| Complement System | a group of serum proteins that act in a cascade to destroy invading microbes; these function to keep blood sterile. |
| Differential White Cell Count | Percentage of each type of white cell in a sample of 100 white blood cells |
| phagocytosis | Ingestion of microbes or particles by a cell, performed by phagocytes. |
| Inflammation | 1. vasodilation 2. Margination and emigration of WBCs 3.Tissue repair |
| Innate immunity | Non-specific defenses against any pathogen |
| Acquired (Adaptive) Immunity | **Naturally acquired active immunity: Resulting from infection **Naturally acquired passive immunity: Transplacental or via colostrum **Artificially acquired active immunity: Injection of Ag (vaccination) **Artificially acquired passive immunity: Injection of Ab |
| Humoral immunity | Involves Ab production by B cells; mostly against bacteria, toxins, and viruses |
| Cell-mediated immunity | Involves T cells; response is against intracellular pathogens and transplanted tissue |
| Haptens | Too small to act as antigen alone |
| Apoptosis | (programmed cell death)- very clean; phagocytes destroy unused B and T cells |
| Necrosis | violent and messy cell death; leads to an inflammatory response |
| B Cells | produce antibodies |
| Antigen-Antibody Binding | -antibodies protect the host by binding to foreign molecules and tagging them for destruction by phagocytosis or by the complement system |
| Affinity | strength of bond between Ag and Ab |
| Specificity | Ab recognizes a specific epitope |
| Cytotoxic T Cells CD8 | destroy target cells with perforin |
| Helper T Cell CD4 | TH1: activate cells related to cell-mediated immunity TH2: activate B cells to produce antibodies |
| vaccine | a suspension of organisms or fractions of organisms used to induce immunity |
| Inactivated (dead) vaccine | injection of dead virulent form of pathogen examples: IPV, rabies, flu shot |
| Conjugated Vaccines | capsular polysaccharide combined with a protien to make it effective for infants. examples: Hib vaccine to prevent meningitis |
| Toxoid vaccines | injection of inactivated toxins examples: tetanus toxoid, diphtheria toxoid |
| indicator of ELISA | peroxidase enzyme |
| direct ELISA | detects antigens |
| indirect ELISA | detects antibodies |
| Type I (Anaphylactic) Reactions | -Involve IgE antibodies (IgE was made instead of IgG in a previous exposure). -Localized: Hives or asthma from contact or inhaled antigens. -Systemic: Shock from ingested or injected antigens. |
| Type II (Cytotoxic) Reactions | -AB reacts to AG on a person's cells -Involve IgG or IgM antibodies and complement activation -Complement activation causes cell lysis (by MAC's) or damage by macrophages that get attracted to the area |
| Type III (Immune Complex) Reactions | IgG antibodies and antigens form complexes that lodge in basement membranes. |
| Type IV (Cell-Mediated) Reactions | -Delayed-type hypersensitivities due to T-cells. -Cytokines attract macrophages and initiate tissue damage. -Contact dermatitis, transplant rejection |
| Autoimmune Diseases | Type I — Cross-reactions with antibodies made against pathogens (Rheumatic fever - anti-Strep-AB's attack heart muscle) Type II — Antibodies react with cell-surface antigens (Myasthenia Gravis - AB's bind at nerve- muscle junction & muscles become progressively weaker) Type III - AB-AG-Complement immune complexes deposit in tissues (Rheumatoid Arthritis -- complexes settle out in joints) Type IV — Mediated by T cells (Multiple Sclerosis -- T-cells attack the myelin sheath) |
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