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  #1  
Old 12-24-2012
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Blood Understanding the Hematocrit Percentage

I feel embarassed to ask this, because this is basic info. i thought i knew this, until i opened up a physio book.

Plasma = 55% of blood volume

that means the other 45% is taken up by blood cells (rbc, wbc, platlets)


this confused me a little, because i know that hematocrit averages around 45%. so this is 45% of the 45% that does not include plasma volume, right? sorry if my question is confusing.

in other words, the hematocrit of 45%, what is this percentage based on? surely it can't be based on total blood volume.
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Old 12-24-2012
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Understanding the Hematocrit Percentage-hematocrit.png
click to enlarge

The figure above makes my question easier to understand:

I understand plasma = 55% blood volume

I understand that formed elements = 45% blood volume

but how does a hematocrit of 45% factor in?

hematocrit is volume of packed RBC's. according to the image above, it should average LESS THAN 45%, to factor out the 'formed elements' contributed by WBC's and platelets.

What am I missing here?
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Old 12-24-2012
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As u can see from picture formed elements other than rbcs make very tiny sediment which compared to rbcs are literally insignificant when measuring htc
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Old 12-24-2012
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hematocrit is everything besides plasma not just rbcs
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Quote:
Originally Posted by MedicalExaminer View Post
As u can see from picture formed elements other than rbcs make very tiny sediment which compared to rbcs are literally insignificant when measuring htc
sounds good, thanks
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Old 12-24-2012
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Quote:
Originally Posted by obinocle View Post
hematocrit is everything besides plasma not just rbcs
i'm pretty sure its the RBC volume
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Old 12-25-2012
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Quote:
Originally Posted by ReggieMiller View Post
i'm pretty sure its the RBC volume
ooops my bad!!
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