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|
|
1
|
removes worn-out red blood cells from blood
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4
|
white blood cells travel through this system
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|
6
|
produces hormones that aid in maturation of white blood cells
|
|
7
|
large cells that eat pathogens and damaged cells
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|
8
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these cells kill bacteria by engulfing them
|
|
9
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immune system keeps these out
|
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11
|
proteins that recognize and bind to antigens
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|
12
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act as filters to trap bacteria
|
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15
|
triggers immune response
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|
17
|
tough protein that forms waterproof cover for skin
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|
18
|
thickest layer of skin
|
|
19
|
provide immunity against pathogens in body fluids
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