# Shared Flashcard Set

## Details

Body Water
Exam #2- Lecture #16
28
Physiology
10/01/2009

Term
 Formula for Total Body Water
Definition
 TBW = (0.7 Lean Body Mass) X (0.1 Adipose Tissue)
Term
 Math Practice: Person #1 weighs 100 kg and has 20% adipose tissue; What is this person's total body water?
Definition
 TBW = 0.7 (80kg) X 0.1 (20 kg)TBW = 56 Liters + 2 LitersTBW = 58 Liters
Term
 If proportion of lean body mass is not known, use what formula?
Definition
 TBW = 0.6(Weight of Person in kg)
Term
 What are the two major fluid compartments of total body water?
Definition
 Intracellular and Extracellular
Term
 What percentage of total body water is intracellular?
Definition
 66%
Term
 What percentage of total body water is extracellular?
Definition
 33%
Term
 What are the divisions of the extracellular fluid? What proportion do they make up in the ECF?
Definition
 Interstitial Fluid and Plasma; 75% and 25%, respectively
Term
 Another formula for Total Body Water
Definition
 TBW = ICF + ECF
Term
 Describe the composition of Interstitial Fluid
Definition
 No proteins; Na+ is the major cation; Cl- is the major anion
Term
 Describe the composition of Extracellular Fluid
Definition
 K+ is the major cation; organic phosphates and proteins are the major anions
Term
 True or False: At equilibrium, all compartments have the same osmolality
Definition
 TRUE
Term
 Formula for Estimating Plasma Osmolality
Definition
 Osmolality (mOsm/kg H20) = 2Na+ (mEq/L) + Glucose (mg/dL)/18 + BUN (mg/dL)/2.8
Term
 Math Practice: Patient has plasma Na+ = 140; plasma glucose = 85; BUN = 15; What is the osmolality?
Definition
 O = (2 X 140) + (85/15) + (15/2.8) = 290
Term
 True or False: The capillary endothelium and most cell membranes are impermeable to water
Definition
 FALSE; They are permeable to water
Term
 True or False: At equilibrium, the plasma, interstitial fluid, and intracellular fluid have the same osmolality at equilibrium
Definition
 TRUE
Term
 Why does water shift between compartments?
Definition
 To maintain equality
Term
 True or False: Electrolytes cross cell membranes
Definition
 FALSE; Na+ and other electrolytes do not cross cell membranes and are actually confined to the ECF
Term
 How is water distribution determined?
Definition
 By the number of osmotically active particles in each compartment
Term
 Where does any loss or gain of water first occur?
Definition
 In the ECF
Term
 Does equilibrium have an affect on ICF?
Definition
 Yes; if equilibrium is upset then ICF changes will also occur
Term
 Name 2 examples of fluid shifts
Definition
 Gain/Loss of an isotonic solution; Gain/Loss of pure water; Gain/Loss of NaCl; Gain of an isotonic glucose solution
Term
 What happens to the cell when there is a gain of an isotonic solution?
Definition
 The ECF volume increases, while the osmolality remains constant
Term
 What happens to the cell when there is a loss of an isotonic solution?
Definition
 The ECF volume decreases, while the osmolality remains constant
Term
 What happens to the cell when there is a gain of pure water?
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
Term
 What happens in the cell when there is a loss of pure water?
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
Term
 What happens in the cell when there is a gain of Sodium?
Definition
 Water moves from the ICF to the ECF, decreasing the volume of the ICF, while increasing the osmolality and volume of the ECF
Term
 What happens in the cell when there is a loss of Sodium?
Definition
 Water moves from the ECF to the ICF, decreasing ECF volume and osmolality, while increasing the volume of the ICF
Term
 What happens in the cell when there is an isotonic glucose infusion?
Definition
 Water moves between the ECF and ICF until equilibrium is reached, while glucose moves from the ECF to the ICF
Supporting users have an ad free experience!