Body Fluids Flashcards
% of lean body mass
% of adipose
LBM = 80%
Adipose = 20%
Lean body mass
Contains the body’s water
73% water
Divided into extracellular and intracellular compartments
Essential fat
Necessary to sustain life
5% of BW in males (12% in females)
Storage fat
Stored subcutaneously between skin and muscles
= 1/2 of the fat in young adults
Other 1/2 = is internalized = visceral fat = more associated with cardio disease
Obesity
Defined as an excess body fat expressed as a percent of BW
Males > 25%
Females > 32%
Hypertrophic = increase fat per cell
Hyperplastic = increased number of cells
Total body water / 0.73 =
Lean body mass
Fat =
Total weight - LBM
Water = % of BW
57%
% body water varies (?) to body fat content
Inversely
During protein folding, water…
Rearranges to accommodate changing exposure of hydrophilic and hydrophobic regions to the water molecules
Intracellular volume
25L
63% of body water
= collective volume of fluid in all cells…
Cells regulate by controlling transport processes and regulating effective solute content within cell
Extracellular volume
15L
37% of body water
Fluid throughout compartment in dynamic equilibrium ‘internal evironment’
Distributed mostly in interstitial space (11.5L)
Remained in vascular compartment (3.5L)
Must be precisely regulated both in terms of composition, totaly solute concentration (osmolality) and volume
Major solutes in EC fluid
Na+, Cl-, HCO3-
Major cation in IC fluid
K+
Anions in IC fluid
Very little Cl- and HCO3-
Most of anionic cahrges are contirbutes by IC proteins and organic anions
Plasma (mMol/L) vs Cell water (mMol/kg H20)
Na+ K+ Cl- HCO3- Osmolality
Na+ 135-145. 10-14
K+. 3.6-5.2. 120-145
Cl- 96-107. ~5-10
HCO3- 22-28. <10
Osmolality. 290. 290
(mOsmol/kg)
Osmolality
Collective concentration of all solutes in solution
Regardless of size and charge…all have same contribution to the osmolality
Anion gap
Difference between the sum of the 2 major cations (Na+ and K+) and the two major anions (Cl- and HCO3-)
Anion gap increases with….increase in organic anions (ketones, acetacetic acid, etc)
—> diabetes mellitus or anaerobic metabolism
Hyponatremia
Low plasma Na+
Mild = 130-134 mM/L
Chronic <129
—> can lead to gout and attention and greater incidence of falls
When occurs rapidly…cerebral edema and death if untreated
Because EC fluid osmolality decreases driving water into cells and increasing cell volume —> brain cell edema
Aquaporins
Water channels that allow water to diffuse across semi permeable membranes
Hypertonic solution
Cell shrinks
Water moves out of cell (where there is less water)
May be associated with dehydration
Obtundation, myoclonus seizures, coma
Hypernatremic encephalopathy
Intracranial hemorrhage
Neuro manifestation occur with sudden changes usually iatrogenic
Hypotonic solution
Cell swells
Water moves into cell (where there is less water)
Increase intracranial pressure
Confusion, seizures, coma, myoclonus
Hypo-osmolar encephalopathy
Important to know if condition is chronic or acute
Steps to calculate changes with infusions of solutions
- Add volume to body column
- Add total mOsmole to body and ECF column
- Calculate equilibrium concentration by dividing new total solute by new volume
- Equilibrium concentration applies to both compartments
- Calculate new volumes of compartments by dividing new total solute by new equilibrium concentration
Indicator substance for measuring total body volume
D20
HTO
