Term
| Formula for Total Body Water |
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Definition
| TBW = (0.7 Lean Body Mass) X (0.1 Adipose Tissue) |
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Term
| Math Practice: Person #1 weighs 100 kg and has 20% adipose tissue; What is this person's total body water? |
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Definition
TBW = 0.7 (80kg) X 0.1 (20 kg)
TBW = 56 Liters + 2 Liters
TBW = 58 Liters |
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Term
| If proportion of lean body mass is not known, use what formula? |
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Definition
| TBW = 0.6(Weight of Person in kg) |
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Term
| What are the two major fluid compartments of total body water? |
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Definition
| Intracellular and Extracellular |
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Term
| What percentage of total body water is intracellular? |
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Definition
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Term
| What percentage of total body water is extracellular? |
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Definition
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Term
| What are the divisions of the extracellular fluid? What proportion do they make up in the ECF? |
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Definition
| Interstitial Fluid and Plasma; 75% and 25%, respectively |
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Term
| Another formula for Total Body Water |
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Definition
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Term
| Describe the composition of Interstitial Fluid |
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Definition
| No proteins; Na+ is the major cation; Cl- is the major anion |
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Term
| Describe the composition of Extracellular Fluid |
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Definition
| K+ is the major cation; organic phosphates and proteins are the major anions |
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Term
| True or False: At equilibrium, all compartments have the same osmolality |
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Definition
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Term
| Formula for Estimating Plasma Osmolality |
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Definition
| Osmolality (mOsm/kg H20) = 2Na+ (mEq/L) + Glucose (mg/dL)/18 + BUN (mg/dL)/2.8 |
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Term
| Math Practice: Patient has plasma Na+ = 140; plasma glucose = 85; BUN = 15; What is the osmolality? |
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Definition
| O = (2 X 140) + (85/15) + (15/2.8) = 290 |
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Term
| True or False: The capillary endothelium and most cell membranes are impermeable to water |
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Definition
| FALSE; They are permeable to water |
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Term
| True or False: At equilibrium, the plasma, interstitial fluid, and intracellular fluid have the same osmolality at equilibrium |
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Definition
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Term
| Why does water shift between compartments? |
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Definition
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Term
| True or False: Electrolytes cross cell membranes |
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Definition
| FALSE; Na+ and other electrolytes do not cross cell membranes and are actually confined to the ECF |
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Term
| How is water distribution determined? |
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Definition
| By the number of osmotically active particles in each compartment |
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Term
| Where does any loss or gain of water first occur? |
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Definition
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Term
| Does equilibrium have an affect on ICF? |
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Definition
| Yes; if equilibrium is upset then ICF changes will also occur |
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Term
| Name 2 examples of fluid shifts |
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Definition
| Gain/Loss of an isotonic solution; Gain/Loss of pure water; Gain/Loss of NaCl; Gain of an isotonic glucose solution |
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Term
| What happens to the cell when there is a gain of an isotonic solution? |
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Definition
| The ECF volume increases, while the osmolality remains constant |
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Term
| What happens to the cell when there is a loss of an isotonic solution? |
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Definition
| The ECF volume decreases, while the osmolality remains constant |
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Term
| What happens to the cell when there is a gain of pure water? |
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Definition
| Water moves from the ECF to the ICF, increasing the volume by 1/3 in the ECF and 2/3 in the ICF, while dilution decreases the osmolality of the ECF |
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Term
| What happens in the cell when there is a loss of pure water? |
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Definition
| Water moves from the ICF to the ECF, decreasing the volume of the ICF by 2/3 and the ECF by 1/3, while concentration of the fluid increases the osmolality of the ECF |
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Term
| What happens in the cell when there is a gain of Sodium? |
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Definition
| Water moves from the ICF to the ECF, decreasing the volume of the ICF, while increasing the osmolality and volume of the ECF |
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Term
| What happens in the cell when there is a loss of Sodium? |
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Definition
| Water moves from the ECF to the ICF, decreasing ECF volume and osmolality, while increasing the volume of the ICF |
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Term
| What happens in the cell when there is an isotonic glucose infusion? |
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Definition
| Water moves between the ECF and ICF until equilibrium is reached, while glucose moves from the ECF to the ICF |
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