Download nonspecific_and _specific_body_defenses

Nonspecific body defenses:
A. surface protection (1st line of defense)
1. Skin
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Prevents entry
Acidic pH prevents bacterial growth
2. Mucous membranes
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Ex: Mucous, gastric juice, cilia, nasal hair,
lining of vagina, tears, saliva
B. Internal defense
1. antimicrobial proteins:
a. interferons – released by
virus-infected cells and prevent viral
replication in neighboring cells
b. transferrins – iron-binding
proteins reduce growth of some
bacteria
2.
Phagocytes and natural killer cells
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Cellular defense
a. phagocytes
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Neutrophils & macrophages (enlarged monocytes)
Engulfs a foreign particle/microbe
Cytoplasm pulls it into vacuole. Binds with lysosome
b. Natural killer cells
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Lymphocytes
Releases chemicals onto target’s cell
membrane to destroy it.
Doesn’t destroy microbes
3. Fever
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temperature of hypothalamus reset by
pyrogens (chemicals secreted by WBCs
exposed to foreign substance)
+ increases speed of repair, inhibit microbe
growth, helps interferons
- denature enzymes of the body if too high
4. Inflammatory response
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kill microbe/prevent spread/tissue repair
Vasodilation
Increased permeability of capillaries
4 cardinal signs of inflammation:
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Redness, heat, swelling, pain
4. Inflammatory response
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kill microbe/prevent spread/tissue repair
Vasodilation  red, heat
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Brings nutrients in blood to injured site
Increased permeability of capillaries  swell
4 cardinal signs of inflammation:
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Redness, heat, swelling, pain
Steps of inflammatory response:

Chemical alarm causes:
 Involved blood vessels to dilate (vasodilation)and
capillaries to become leaky (increased permeability).
 Vasodilation
increases nutrients to area (causes redness and
heat. Heat increases metabolism of tissue cells)
 Permeability of capillaries allows plasma to leak (causing
clotting proteins to “wall off” damaged area and edema –
swelling – which activates pain receptors)
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Activation of pain receptors
 Possibly
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to cause immobilization and therefore rest
Attract phagocytes and WBCs to area
 For
clean-up: disposes of cell debris and pathogens