Body Fluid Compartments Flashcards
What is needed to calculate the osmolarity
Molar conc and num of osmotic active particle
What is osmolality
Has units of osmoles/kg of water
What is tonicity
Related to its effect on cell volume
What is isotonic
Same cell would have no change in cell vol
Hypotonic
More
Solution causes an increase in cell vol as water enters the cell could lead to burst or lysis of cell
Hypertonic
Less
Solution causes a decrease in cell volume as water leaves the cell
Why does the total body water differ in make and females
Woman have more fatty tissue threef ore less lean tissue and less water
What are the two water compartments of the total body water
Intracellular - 67%
Extra cellular -33%
What does extracellular fluid includes
Plasma - 20%
Interstitial fluid -80%,
What is used to determine the volume of specific fluid compartments
Tracers Used in: Tbw --> titrated water Ecf --> inulin Plasma --> labelelled albumin
How is the volume of water calc in container
V(litres) = dose/sample concentration
What is insensible loss.
Uncontrollable occurs without realisation
Skin
Lungs
What is sensible loss
Can realise is loss
Sweat
Urine
Faeces
What is the ionic composition of sodium in the ICF -
And ECF
ICF - 10mM
ECF - 140mM
What is the ionic composition of pottasium in the ICF -
And ECF
ICF - 140mM
ECF - 4.5mM
What is the ionic composition of chooride in the ICF -
And ECF
ICF - 7mM
ECF - 115mM
What is the ionic composition of bicarbonate in the ICF -
And ECF
ICF - 10mM
ECF - 28mM
What are the separating membranes between the plasma, interstitial fluid, intracellular fluid
Between plasma and interstitial fluid –> capillary wall
Between interstitial fluid and intracellular fluid –> plasma mem
What is a fluid shift
Movement of water between ICF and ECF in repsonse to an osmotic gradient
What does the gain or loss of water do to fluid homeostasis
Change in fluid osmolarity similar changes in ICF and ECF volumes
What dos gain or loss of Nacl do to the fluid homeostasis
Change in osmolarity
(a) sodium excluded from ICF
(b) osmotic water movements
These two factors combine to produce opposite changes in ICF and ECF
What does gain or loss of isotonic fluid do to the fluid homeostasis
No change in fluid osmolarity change in ECF volume only
What does the kidneys do to the ECF
Alter composition and volume which affects blood pressure
What do electrolytes do in solution
Dissociate into free ions in solution.
Why is it port any to maintain electrolyte balance
Total electrolyte concs can directly affect water balance
The concs of individual electrolytes can affect cell functions
Why are sodium and pottasium particularly important
Major contributors to osmotic concentrations of ECF and ICF
Directly affect functioning of all cells
What is the balance of sodium in the ECF represent a balance between what two factors
Input of sodium form diet and output excreted in urine
Sodium is present where which means what
Mainly present in ECF meaning it is a major determinant of ECF volume
Why is minor fluctuations of pottasium bad for the cell
Pottasium is imp to establish resting membrane potential in cells and resting membrane potential
If there are leakages of pottasium or increased cellular uptake what does this lead to
Weakness of muscles - paralysis
Cardiac irregularities - cardiac arrest
What is osmolarity
Concentration of osmotically active particles present in solution
