Overview of the Immune System & Comparative Immunology

Vocabulary flashcards reviewing core principles, historical developments, comparative taxons, and key terms in introductory immunology.

Immune System

A complex network that evolved to protect organisms against pathogens, including bacteria, fungi, viruses, and multicellular parasites.

Innate Immunity

A broad set of non-specific disease resistance mechanisms that act quickly to destroy pathogens or hold them at bay, serving as an essential precursor to activating adaptive immunity.

Adaptive Immunity

A highly specific defense system found only in vertebrates that retains immunological memory of encountered pathogens, allowing for faster and stronger responses upon re-exposure.

Host

An organism or species that harbors a pathogen.

Comparative Immunity in Organisms

The distinct mechanisms used by different taxa to defend against pathogens: plants, fungi, and unicellular organisms rely solely on innate or innate-like defenses, whereas jawed vertebrates possess both innate and adaptive immunity.

Dioctophyme renale

A giant parasitic kidney worm that can grow over $100\,\text{cm}$ in length and $10\,\text{mm}$ in width, illustrating the massive size range of pathogens the mammalian immune system can respond to.

The Red Queen Hypothesis

An evolutionary concept proposed by Leigh van Valen stating that organisms must continually adapt in an antagonistic arms race against pathogens and parasites simply to maintain their survival.

Antigenic Variation

An immune evasion strategy used by pathogens like the influenza virus, where surface antigens change so that existing memory B cell antibodies and T cell receptors can no longer recognize them.

Cytokines

Chemical messengers secreted by immune cells that mediate communication and signaling between the immune, nervous, and endocrine systems.

Variolation

An early immunization procedure practiced in 15th-century China and Turkey involving the inhalation or skin insertion of dried scabs from smallpox pustules.

Edward Jenner

The physician who, in 1798, established modern vaccination by inoculating humans with cowpox fluid to grant protective immunity against smallpox.

Pasteurella multocida

The bacterial pathogen causing chicken cholera that Louis Pasteur used to discover the principle of attenuation in vaccines.

Attenuation

The process of reducing a pathogen's virulence (for example, through aging or oxygen exposure) so that it stimulates protective immunity without causing severe disease.

Joseph Meister

The young boy who, in 1885, became the first human to successfully receive Louis Pasteur's rabies vaccine after suffering severe bites from a rabid dog.

Julian H. Lewis

A scientist ($1891$\text{--}$1989$) who challenged racial theories in blood typing, presenting the first formal scientific argument refuting the notion of a 'superior' race.

Winifred M. Ashby

The researcher ($1879$\text{--}$1975$) who created the Ashby method to measure red blood cell lifespan, revolutionizing blood transfusion techniques and blood storage during World War II.

Variola major

The viral pathogen responsible for smallpox, characterized by a $30\%$ mortality rate, which was declared globally eradicated in 1980 through widespread vaccination.

Herd Immunity

The indirect protection from infectious disease that occurs when a sufficiently high percentage of a population becomes immune, creating a buffer that shields unimmunized or immunocompromised individuals.