ImmunologyLesson 1 of 2 in the course Innate Nonspecific Host Defenses

Physical Barriers, Mechanical Defenses, and the Microbiome

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

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Summary

Physical barriers are among the body's most basic defenses against infection. They keep microbes from reaching tissues where they could multiply and cause disease. This lesson introduces the role of tightly joined cells and explores how the skin protects the body.

Many tissues form barriers from cells that are closely connected to one another. These connections limit the spaces through which microbes might pass to reach deeper tissues. For example, endothelial cells lining blood vessels have very tight cell-to-cell junctions that help prevent microbes from entering the bloodstream.

All flashcards

Tight junctions
Cell-to-cell connections that limit spaces microbes could cross to reach deeper tissues.
Skin surface fatty acids
They help create a dry, salty, acidic environment that inhibits the growth of some microbes.
Mucociliary escalator
Coordinated ciliary movement that carries mucus and trapped material away from the lungs.
Resident microbiota
Microbes that can limit pathogens by occupying cellular binding sites and competing for nutrients.
Fecal transplantation
Transfer of screened donor fecal material into the intestines to help restore a healthy microbial community.

Quiz questions

  1. What do tight junctions in blood vessels traveling through the central nervous system help prevent?Answer: Microbes in the blood entering the brain and spinal cord.
  2. What is one protective role of mucus on mucous membranes?Answer: It traps microbes and debris while covering more fragile cells.
  3. How can resident microbiota make it harder for pathogens to establish infection?Answer: They occupy binding sites and compete for nutrients.
  4. Why can antibiotic treatment increase the risk of gut colonization by Clostridioides difficile?Answer: Reducing normal gut microbiota can lessen competition against the pathogen.
  5. How can a thorn puncture allow Sporothrix schenckii to cause infection?Answer: The puncture can breach the skin and let the fungus enter tissue.

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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