Question | Answer |
Active immunity | the immune system responds to antigen by producing antibodies and specific lymphocytes |
Acute period | The phase of disease in which specific symptoms occur and the disease is at its height |
Antibody | a highly specific protein produced by the body in response to a foreign substance |
Antibody-mediated immunity | the form of acquired immunity conferred to an individual through the activity of B cells and the production of antibodies |
Antigen | a substance that stimulates an immune response |
Antigen binding site | the region on antibody that binds to an antigen |
Antigenic determinant | a section of an antigen molecule that binds to the antibody binding site and stimulates an immune response |
Epitope | a section of an antigen molecule that binds to the antibody binding site and stimulates an immune response |
Antitoxin | an antibody produced by the body that circulates in the blood stream to provide protection against toxins by neutralizing them |
Avirulent | referring to an organism that is not likely to cause disease |
Biological vector | an infected arthropod that transmits disease-causing organisms between hosts |
B lymphocyte | a white blood cell that matures into memory cells and plasma cells that secrete antibody |
Carrier | an individual that has recovered from a disease but retains and continues to shed the infectious agent |
Cell mediated immunity | the body’s ability to resist infection through the activity of T-lymphocyte recognition of antigen peptides presented on macrophages and dendritic cells and on infected cells |
Commensalism | a close an permanent association between two species of organisms in which one species benefits and the other remains unharmed or unaffected |
Cytotoxic T cells | The type of T-lymphocyte that searches out and destroys infected cells |
Diagnosis | the process of identifying a disease, illness or problem by examining an individual |
Direct contact | the form of disease transmission involving close association between hosts |
Droplet | an airborne particle of mucus and sputum from the respiratory tract that contains disease-causing microorganisms |
Endemic | referring to a constant presence of disease or persistence of an infectious agent at low levels in a population |
Endotoxin | a metabolic poison, produced chiefly by gram-negative bacteria that are part of the bacterial cell wall, composed of lipid-polysaccharide-protein complexes |
Fecal-oral route | a route of disease transmission, where pathogens in fecal material pass from one person and are introduced into the oral cavity of another person |
Fever | an abnormally high body temperature that is usually caused by a bacterial or viral infection |
Fomite | an inanimate object that carries disease organisms |
Heavy chain | the larger polypeptide in an antibody molecule |
Helper T cell | A T-lymphocyte that enhances the activity of B-lymphocytes and stimulates destruction of macrophages infected with bacteria |
Host | an organism infected by a pathogen |
Hyaluronidase | an enzyme that digests hyaluronic acid and thereby permits the penetration of pathogens through connective tissue |
Incubation period | the time that elapses between the entry of a pathogen into the host and the appearance of signs and symptoms |
Indirect contact | the mode of disease transmission involving nonliving objects |
Infection | The invasion and multiplication of microorganisms such as bacteria, viruses, and parasites that are not normally present within the body |
Infectious dose | the number of microorganisms needed to bring about infection |
Inflammation | a nonspecific defense response to injury; usually characterized by redness, warmth, swelling and pain |
Interferon | an antiviral protein produced by body cells upon exposure to viruses |
Invasiveness | the ability of a pathogen to spread from one point to adjacent areas in the host and cause structural damage to those tissues |
Light chain | a smaller polypeptide in an antibody |
Lymphocyte | a type of white blood cell that functions in the immune system |
Lysozyme | an enzyme found in tears and saliva that digests the peptidoglycan of gram-positive bacterial cell walls |
Macrophage | a large cell derived from monocytes that is found within various tissues and actively engulfs foreign material |
Mechanical vector | a living organisms, or object, that transmits disease agents on its surface |
Memory B cell | a cell derived from B lymphocytes that reacts rapidly upon re-exposure to an antigen |
Memory T cell | a cell derived from T lymphocytes that reacts rapidly upon re-exposure to an antigen |
Mucus | a sticky secretion of viscous fluid |
Mucous membrane | a moist lining in the body passages of all mammals that contains mucus-secreting cells and is directly or indirectly to the external environment |
Mutualism | a close and permanent association between two populations if organisms in which both benefit from the association |
Opportunistic | referring to pathogens that only cause disease when the person’s immune system is weakened |
Outbreak | a small, localized epidemic |
Pandemic | refers to a disease occurring over a wide geographic area (worldwide) and affecting a substantial proportion of the global population |
Parasitism | a close association between two organisms in which one (the parasite) feeds on the other (the host) and may cause injury to the host |
Passive immunity | the temporary immunity that comes from receiving antibodies from another source |
Pathogenicity | the ability of a disease-causing agent to gain entry to a host and bring about a physiological or anatomical change interpreted as disease |
Period of convalescence | the phase of disease during which the body’s systems return to normal |
Period of decline | the phase of disease during which the symptoms subside |
Phagocyte | a white blood cell capable of engulfing and destroying foreign materials or cells |
Phagocytosis | a process by which foreign material or cells are taken into a white blood cell and destroyed |
Plasma cell | an antibody-producing cell derived from B lymphocytes |
Portal of entry | the site at which a pathogen enters the host |
Portal of exit | the site at which a pathogen exits the host |
Probiotic | living microbes that help reestablish or maintain the human microbiota of the gut |
Prodromal phase | the phase of disease during which general symptoms occur in the body |
Pyrogen | a fever producing substance |
Reservoir | the location or organism where disease-causing agents exist and maintain their ability for infection |
Serum | the fluid portion of the blood consisting of water, minerals, salts, proteins, and other organic substances including antibodies |
Sign | a indication of the presence of a disease |
Symbiosis | an interrelationship between two populations of organisms where there is a close permanent association |
Symptom | an indication of some disease or other disorder that is experienced by the patient |
Syndrome | a collection of signs or symptoms that together are characteristic of a disease |
T lymphocyte | a type of white blood cell that matures in the thymus gland and is associated with cell-mediated immunity |
Toxin | a poisonous chemical substance produced by an organism |
Toxoid | a preparation of microbial toxin that has been rendered harmless by chemical treatment but that is capable of stimulating antibodies |
Virulence | the degree to which a pathogen is capable of causing a disease |
zoonosis | a disease spread from another animal to humans |