ImmunologyLesson 2 of 2 in the course Innate Nonspecific Host Defenses

Innate Chemical Defenses: Peptides, Complement, and Inflammatory Signals

5 flashcards · 5 quiz questions · 5 match pairs · 5 fill-in sentences · English

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Summary

Chemical defenses are substances in body fluids and tissues that help prevent microbes from colonizing or causing infection. They may act alone or work together with physical and cellular defenses.

A chemical mediator is a substance that helps inhibit microbial growth, attachment, or survival. An endogenous mediator is produced by human cells; an exogenous mediator is made by another organism, including a member of the normal microbiota. Some mediators are continually present, while others are produced or activated in response to a stimulus such as infection.

All flashcards

What is a chemical mediator in innate defense?
A substance that helps inhibit microbial growth, attachment, or survival.
How do defensins commonly affect microbes?
They commonly damage microbial plasma membranes and can act against bacteria, fungi, and many viruses.
What does mannose-binding lectin do in innate immunity?
It binds carbohydrates on microbial surfaces and can initiate the lectin complement pathway.
What is the membrane attack complex (MAC)?
A complement protein complex that forms pores and can lyse susceptible cells.
What is an acute-phase protein?
A blood protein, usually made by the liver, whose level or activity changes in response to inflammatory signals.

Quiz questions

  1. Which event initiates the alternative complement pathway?Answer: Spontaneous C3 activation produces C3a and C3b.
  2. How do type I interferons help limit viral infection?Answer: They induce antiviral changes in nearby cells that slow viral replication.
  3. What distinguishes autocrine cytokine signaling?Answer: The cell that releases the signal responds to it.
  4. Which acute-phase protein can coat bacteria and promote their uptake by phagocytes?Answer: C-reactive protein
  5. Which effect is associated with histamine release during inflammation?Answer: Vasodilation and increased vascular permeability

Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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