Term
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Definition
| consists of intracellular and extracellular fluid combined |
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Term
| intracellular fluid (ICF) |
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Definition
2/3 TBW
intracellular fluid compartment consists of tthe combined totality of fluid contained within each cell.
~75 trillion small compartments of fluid similar in composition, thus considered to be (for practical purposes) one compartment
barrier separating the ICF from the ECF is a selectively permeable membrane |
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Term
| extracellular fluid (ECF) |
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Definition
consists of all the fluid outside the confines of the cell membrane
1/3 TBW
divided into 3 subcategories:
--interstitial fluid
--plasma
--transcellular fluid |
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Term
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Definition
~80% of ECF
consists of ECF which is present in the interstices (i.e. spaces) between the cells.
"go between" of plasma and ICF
plasma membrane separating ISF from ICF is permeable to water, but not to solute |
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Term
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Definition
~20% of ECF
consists of the extracellular fluid which is the fluid portion of the blood.
confined within blood vessels
capillary walls separate the plasma from the ISF. This barrier is freely permeable to water and ions. Proteins are too large to pass through this barrier, therefore plasma has more protein than ISF |
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Term
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Definition
| denotes the ECF that is neither interstitial nor plasma (fluid "trapped" in localized compartments such as cerebrospinal fluid, synovial fluid joints, intraocular fluid, as well as fluid in the pericardial and pleural spaces.) |
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