NonSpecific Internal Defenses Against Infection

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Non-Specific Internal Defenses Against Infection
Division II MST Winter/Spring 2007
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Phagocytosis
White Blood Cells known as phagocytes can eat
microbes such as bacteria. The process is known
as phagocytosis. There are two types of
phagocytes Macrophages which are found in
various tissues in the body and
Neutrophils which are found in blood
vessels Click on the image of the
macrophageeating a parasite to view an
animationof how phagocytosis works. Image from
http//www.biologyreference.com/Mo-Nu/Nonspecific-
Defense.html
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Natural Killer Cells

• Natural Killer Cells are white blood cells that
  will destroy your bodys own cells, when a virus
  has infected the cells.

• Viruses infect a cell in your body, multiply and
  then move to infect other cells.
• Natural killer cells prevent the virus from
  spreading by killing the infected cell before the
  virus has moved on.

Image from http//www.muskingum.edu/brianb/CellP
hys/Lect18/img014.jpg
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Inflammatory Response(Inflammation)

• Breaches of the skin and mucous membranes (ex. a
  cut) can inflame the bodys defenses.
• Damaged cells release the chemical histamine.
• 2. Histamine causes capillary walls close to the
  injury to become leaky causing redness,
  swelling and heat near the injury.
• White blood cells leak through the capillary
  walls and move towards the wounded tissue to
  attack foreign invaders.
• 4. Histamine and other chemicals call other
  phagocytes to the site of the infection.

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Inflammatory Response
Image from http//www.uic.edu/classes/bios/bios1
00/lecturesf04am/lect23.htm
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Fever
Our bodies raise our internal temperature in
order to fight an infection that has spread to
larger areas of our body.

• Increased body temperature
• Reduces the rate of reproduction of some
  microbes.
• Increases the activity of phagocytes.
• Increases the production of interferon, which is
  a protein
• molecule that which helps cells prevent viruses
  from
• multiplying.