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13.2. Defense mechanisms against infections

Defense mechanisms against infections

There are two types of defense mechanisms against infections:

  • Nonspecific defense mechanisms.
    • Two types of barriers:
      • Primary barriers: external barriers (physical, mechanical, chemical and microbiological), which prevent pathogens from invading the body.
      • Secondary barriers: phagocytes. The innate immune system.
    • They are not specific to a particular pathogen.
    • No prior contact with the pathogen is necessary to trigger it.
    • Its action is immediate.
    • Lacks immune memory.
  • Specific defense mechanisms.
    • Third barrier: internal defenses. The adaptive immune system, whose immune response can be:
    • There is a specific response against pathogens and antigens.
    • Its action is triggered after a previous contact with the pathogen.
    • Has immune memory.
      • Primary immune response: takes 3-4 days to be effective.
      • Secondary immune response: if memory cells are present, the response is faster and longer lasting.

Questions that have come out in University entrance exams (Selectividad, EBAU, EvAU)

Canary Islands, July 2020, option A, question 10

The defensive barriers that protect man from pathogenic organisms can be specific or nonspecific:

a.- How are specific and nonspecific defensive barriers different?
b.- Cite an example for each type of barrier.

Murcia, June 2018, option A, question 7.

In relation to organic defense mechanisms, what are the differences between specific and non-specific defenses? (1 point)


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