Body Fluid Flashcards
Why do women have lower % water composition?
due to more adipose (fat) tissue, which has very low water %
What happens to % water composition with age?
decreases, due to more adipose (fat) tissue
What is intracellular fluid?
fluid found in cells, including blood cells
What is extracellular fluid?
fluid found outside cells
What are the 3 types of extracellular fluid in the body?
- transcellular fluid
- interstitial fluid
- plasma
What is transcellular fluid?
fluid found on other side of epithelial tissue
does NOT include fluid continuous with outside of body
What is interstitial fluid?
fluid that surrounds tissues
What is plasma?
fluid component of blood
What is the total body water in an individual?
60% of body weight
42 L – based on 70 kg male
What is the breakdown of ECF and ICF in total body water?
ECF: 20% of body weight (1/3 of TBW)
ICF: 40% of body weight (2/3 of TBW)
14 L and 28 L – based on 70 kg male
What is the breakdown of fluid in the ECF?
1/20 transcellular fluid
3/4 interstitial fluid
1/5 plasma
< 1 L, 10.5 L, and 3 L Based on 70 kg male
What separates ECF and ICF?
cell membrane
What separates transcellular fluid and interstitial fluid?
epithelium
What separates interstitial fluid and plasma?
capillary wall
What is the permeability of the plasma membrane?
varies from area to area, depending on types of proteins expressed in different cells
Compare the composition of ions in plasma an interstitial fluid (ECF).
similar
Describe the composition of ions in transcellular fluid.
variable
What are the 3 locations of interstitial fluid?
- bulk interstitial fluid
- bone
- dense connective tissue
What is the Na+ and K+ composition in ICF?
- low Na+ (sodium is leaving cell)
- high K+ (potassium is entering cell)
due to Na+-K+ ATPase
Compare [Na+], [K+], [Cl-], [protein], and osmolality in ECF vs. ICF.
- ECF: 145 mM
- ICF: 15 mM
- ECF: 4.5 mM
- ICF: 120 mM
- ECF: 116 mM
- ICF: 20 mM
- ECF: 0 mM
- ICF: 4 mM
osmolality: ECF = ICF
- ECF: 290 mOsm
- ICF: 290 mOsm
What are the units for solute concentration?
- mmol/L (mM)
- mEq/L
- mOsm/kg H2O (osmolality)
- mOsm/L H2O (osmolarity)
What is an equivalent (Eq)?
number of moles of charge (1 Eq = 1 mole of charge)
How is mEq/L calculated?
mmol/L x z (valence)
What is osmolality?
mOsm/kg H2O
describe concentration of active solute per unit of H2O – by mass
What is osmolarity?
mOsm/L H2O
describe concentration of active solute per unit of H2O – by volume
What is an osmole (Osm)?
number of moles of osmotically active (capable of causing osmosis) particles
How does H2O move based on osmolality?
moves from lower to higher osmolality
What can move through semipermeable membrane?
H2O
solute (ie. ions) cannot
What is the movement of ions dependent on?
is highly regulated and dependent on what is expressed in tissues
Are many of our tissues are relatively permeable to water?
yes
What can osmolarity be altered by?
changes in temperature
Is it better to use osmolarity or osmolality? Why?
best to use osmolality (not altered by temperature)
When is osmolarity and osmolality equal?
at body temperature (37℃), 1 L H2O = 1 kg H2O
What does isosmotic mean?
osmolality of all fluid compartments are considered to be equal
Does solute occupy volume in plasma?
yes
Describe solute concentration in plasma volume vs. plasma water.
calculating concentrations using plasma water gives a different result than using plasma volume
plasma volume: uses volume of solute + H2O
plasma water: uses volume of H2O only
Is solute concentration greater in plasma water or plasma volume?
ALWAYS greater in plasma water
What fluid is Na+ the main cation in?
- plasma
- interstitial fluid
What fluid is K+ the main cation in?
intracellular fluid – due to Na+-K+ ATPase pump
What fluid is Cl- in?
extracellular fluid
What fluid are phosphates and organic anions in?
intracellular fluid
Does interstitial space have protein?
very little
In which fluid is there more protein?
ICF
some in plasma
In which fluid is there a greater amount of Ca2+?
greater outside cell (ECF) than inside cell (ICF)
What is the Gibbs-Donnan effect?
describes what happens when a membrane is permeable to some, but not all, molecules in a solution
fluid shifts
What is albumen?
very negatively-charged protein in plasma (found in blood)
Where does transport between plasma and interstitium (ISF) occur in?
- blood capillaries, across endothelial cells
- lymphatic capillaries, across endothelial cells, which subsequently drain into venous blood system
Where does transport between cells (ICF) and interstitium (ISF) occur?
across cell membranes
- highly regulated and dependent on what is expressed in tissue
- different types of proteins and transporters expressed in different permeabilities, depending on location of body
Where does transport between transcellular fluid (TCF) and interstitium (ISF) occur?
across epithelial cells
What is transport across barriers determined by?
their specific permeability
Describe fluid loss when you sweat.
ECF fluid (water) loss > ECF salt loss
Describe fluid loss when you have diarrhea.
ECF fluid loss similar to ECF salt loss
Describe fluid gain when you drink H2O excessively.
ECF fluid gain
What is intracellular osmotic shift?
swelling of cells when fluid moves into cells
Where is intracellular osmotic shift dangerous?
in areas of body that don’t have room for tissue expansion
What are symptoms of intracellular osmotic shift?
headache
seizures
coma leading to death
