The Biology Project: Immunology

Immunology Problem Set

Problem 3: Initial immune response

Tutorial to answer the question:

Immediately following a break in the skin, phagocytes engulf bacteria within the wound. This is an example of an _________ immune response which is __________ against a pathogen.

A. adaptive, specific
B. innate, specific
C. innate, nonspecific

adaptive, nonspecific


Innate defenses begin to act very soon after the appearance of a pathogen in the body. Innate defenses are nonspecific – they target any pathogen. Innate defenses include:

  • Skin, which excludes most pathogens from entering the body
  • Cilia in mucous membranes, which sweep out airborne pathogens and dust
  • Tears, nasal secretions and saliva, which contain bacteria-destroying enzymes
  • Specialized phagocytic cells ("phago-"=eating, "cyte"=cell) which migrate to affected areas and engulf pathogens.
Phagocytic cells include granulocytes (or neutrophils), macrophages, and dendritic cells that are part of the white blood cell fraction. Pathogens and infected cells produce chemokines, peptides that increase the permeability of blood vessels. This permits a migration of white blood cells toward the wound, causing the redness and inflammation associated with infection.

Microscopic movie of macrophages
ingesting a yeast
(567 kb)

Adaptive immune responses are antigen-specific. Adaptive immune responses include production of antibody and destruction of infected cells.


Problem 3 | Answer | Problem 4

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