Infectious Disease and Immune System

Vocabulary flashcards covering infectious disease pathogens, transmission methods, disease control, adaptations, innate immunity, adaptive immunity, and types of active/passive immunity.

Infectious Disease

A disease that is transmitted from one organism to another, caused by pathogens that destroy cells or release toxins that disrupt normal cell function.

Non-infectious Disease

A disease that cannot be transmitted from one organism to another and is caused by a wide variety of non-pathogenic factors.

Pathogen

A disease-causing microbe that has developed characteristics enabling it to exploit the warm, nutrient-rich, and moist environment of its host.

Bacterium Structure

Unicellular, prokaryotic organism containing structures such as a nucleoid, mesosome, flagellum, cell wall, plasma membrane, and ribosomes, which reproduces via binary fission.

Fungi

Heterotrophic organisms fitting into two main groups (yeasts and moulds) that can grow on the surface, superficial layers, subcutaneous tissues, or inner tissues/organs of a host.

Protists

Heterotrophic pathogenic microorganisms that absorb nutrients from their host and are classified into intestinal, uro-genital, and blood and tissue groups.

Virus

An extremely small, non-living infective particle consisting of RNA or DNA surrounded by a protein coat that replicates by using host cells.

Prion

An unusual infective agent of the nervous system that converts normal protein into abnormal protein, causing lesions in the brain.

Droplet Infection

A mode of transmission where pathogens inside small mouth or respiratory droplets released by coughing or sneezing are inhaled by another person.

Vector

An intermediate host or organism (such as a house fly, mosquito, mite, flea, fox, or dog) involved in transmitting infective agents to another host.

Epidemic

An occurrence where a particular pathogen spreads its disease more than usual in a short space of time, leading to widespread infection.

Pandemic

An epidemic that has spread globally across multiple countries or continents.

Antibiotic Resistance

A phenomenon where resistant bacterial strains survive exposure to antibiotics and pass their resistance to offspring, creating 'superbugs'.

Herd Immunity

Protection provided to a whole community—including those who cannot be vaccinated—when a high percentage of the population is immune to a specific infection.

Antibiotics

Chemicals that work specifically by killing or reducing the growth of bacteria inside a host.

Antiseptics

Chemical substances (such as alcohol, hydrogen peroxide, and iodine) used to kill microbes on the outside of the body.

Disinfectants

Chemicals used to kill microbes on non-living surfaces, floors, and toilets in hospitals, homes, and the food industry.

Quarantine

The practice of keeping individuals infected with a disease separate from healthy members of the population to prevent spread.

Pathogenicity

The ability of a pathogen to cause disease in a host.

Virulence

The degree or intensity to which a pathogen causes disease in its host.

Biofilm

A bacterial colony encased in a slime-like substance that protects the bacteria from identification and renders them resistant to antibiotics.

Innate Immune System

A non-specific, rapid, non-learned line of defense present from birth in all animals that responds in a similar way to every infection.

Phagocytosis

A specific cellular process where phagocytes recognize, bind to, engulf, and degrade microbes using lysosomal enzymes in sequential phases.

Neutrophils

Short-lived, abundant white blood cells in the bloodstream that quickly migrate to infection sites to engulf and destroy pathogens.

Macrophages

Long-lived, tissue-bound 'big eater' phagocytes that develop from monocytes and ingest pathogens, cancer cells, and cellular debris.

Mast Cells

Immune cells located in mucous membranes and tissues that release histamine and cytokines to trigger inflammatory responses.

Cytokines

Small signaling proteins produced by immune cells that communicate between cells to activate, inhibit, or direct traffic of immune cells.

Natural Killer Cells (NK cells)

Immune cells that recognize 'non-self' or altered cells (virally infected or cancerous) and release perforin and granzymes to induce cell lysis.

Complement Pathways

A system of ~30 proteins activated via Classical, MB-Lectin, or Alternative pathways to recruit inflammatory cells, opsonize pathogens, or kill pathogens directly.

Interferons

Proteins secreted by virus-infected cells that aim to limit the spread and multiplication of viruses to surrounding cells.

Inflammatory Response

A second-line tissue reaction characterized by heat, swelling, redness, and pain, mediated by chemical signals, capillary widening, and phagocyte recruitment.

Adaptive Immune System

A highly specific immune defense line that recognizes specific antigens, retains immunological memory, and produces a larger response upon secondary exposure.

Major Histocompatibility Complex (MHC)

A set of protein markers on cell surfaces displaying 'self' unique individual proteins or 'non-self' foreign pathogen proteins.

B Lymphocytes

White blood cells originating in bone marrow that possess specific receptors and release antibodies to bind and neutralize foreign antigens.

Types of T Cells

Includes cytotoxic T cells (produce toxic agents to kill targets), helper T cells (stimulate B cells and T cells), and regulatory T cells (suppress immune responses).

Active Immunity

Long-lasting immunity resulting from the production of antibodies by a person's own immune system in response to direct contact with an antigen.

Passive Immunity

Short-term immunity resulting from the introduction of antibodies created outside the body, providing immediate protection without immunological memory.

Live, Attenuated Vaccines

Vaccines containing a weakened version of a living virus or bacterium that stimulates an immune response without causing serious disease.

mRNA Vaccines

Vaccines that introduce a piece of messenger RNA corresponding to a viral surface protein to teach body cells how to trigger an immune response.

Neonatal Fc Receptor (FcRn)

A helper molecule that binds to maternal IgG antibodies and pumps them across the placenta into fetal blood during the third trimester.

Antiserum

An antibody-containing preparation injected into a person to provide artificial passive immunity (e.g., snake antivenom or rabies treatment).