Physics

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Chapter 17 THE IMMUNE SYSTEM AND DISEASE
17.1 Viruses 17.2 Innate Immunity 17.3
Adaptive Immunity 17.4 Disruptions in the Immune
System
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Viruses are acellular, parasitic entities that
are not considered alive because Viruses
infect all forms of organisms
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discovered after the development of a porcelain
filter used to extract bacteria from liquid
tobacco mosaic disease
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Virions, single virus particles, are very small,
about 20250 nanometers (1 nanometer
1/1,000,000 mm).
Virions 20-250/1,000,000 mm
How Big is a...?
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electron microscope in the 1940s
virion
Classification based on morphology gt nucleic
acid gt molecular analysis
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FIGURE 17.6

• In influenza virus infection, glycoproteins
  attach to a host epithelial cell. As a result,
  the virus is engulfed. RNA and proteins are made
  and assembled into new virions.

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Influenza virus is packaged in a viral envelope,
which fuses with the plasma membrane. This way,
the virus can exit the host cell without killing
it. What advantage does the virus gain by keeping
the host cell alive?
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Which of the following statements about virus
structure is true? a. All viruses are encased in
a viral membrane. b. The capsomere is made up of
small protein subunits called capsids. c. DNA is
the genetic material in all viruses. d.
Glycoproteins help the virus attach to the host
cell.
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Figure 17.7

• Viruses are the cause of dozens of ailments in
  humans, ranging from mild illnesses to serious
  diseases. (credit modification of work by Mikael
  Häggström)

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Vaccines for Prevention
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Figure 17.8

• There are two main parts to the vertebrate immune
  system. The innate immune system, which is made
  up of physical barriers and internal defenses,
  responds to all pathogens. The adaptive immune
  system is highly specific.

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Figure 17.11

• Cells involved in the innate immune response
  include mast cells, natural killer cells, and
  white blood cells, such as monocytes, macrophages
  and neutrophils.