Body Fluids 7

 is the concentration of osmotically active particles per liter of solution

 is the flow of water between two solutions separated by an
semipermeable membrane

  is the driving force for osmosis is caused by the presence of a
solute

  a measure of the number of osmotically active particles per
kilogram of H 2 O

*** The extent to which a particular solute crosses a
particular membrane is expressed by a dimensionless factor

 : The number of particles that a solute dissociates to

  the effect of a solution on a cell

Steady state must be maintained for 

Steady State is a set point “Set point   mOsm/kg H 2 O” body osmolarity ( osmolarity =
  osmolarity)"

Water input= water  

Water input :  / 
Water Output:  ,  ,  ,  

While   and  are present in the extracellular fluid,  and   are not found in high quantities the extracellular fluid. Glucose is most found extracellularly in  

  of body is made up of water and   is made up of intracellular fluid and   is made up intracellular fluid (percentages).

Of the total body Water (TBW),   is intracellular fluid and   is extracellular fluis

Extracellular fluid is divided into   and  . These spaces are divided by the   The part with the plasma is also referred to as intravascular volume.

Movement of Fluid in the Extracellular Fluid
Depends on
1. capillary type
(sinusoidal, fenestrated or
continuous)
2. Movement between  and   (  forces)
3.   pressure and
  pressure difference
between ISF and Plasma is
what regulates
absorption/filtration

The two important factors that impact movement across a capillary are  and  .

Osmotic pressure is created by the presence of   in solution

 law tells us that osmotic pressure is determined by the number of solute molecules

Osmolarity =   x  

While   is the concentration of osmoles per kg H2O,  is the concentration of osmoles per L H20

Osmolarity vs Osmolality
Roughly equivalent because 1 L of pure H2O weighs 1 Kg
In practice   <  

Tonicity refers to the effect of a solution on a cell, therefore it depends on “  osmoles”

 solutions: have a higher effective osmotic pressure

  solutions: have same effective osmotic pressure

  solutions: lower effective osmotic pressure

Effective osmoles produce osmotic pressure due
to their inability to  

Isotonic =  , Hypertonic =  , Hypotonic =  

****Effectuve versus ineffective osmole is measure by the  

If something is able to distrubute easily, it is an   osmole. If something is imperable to the substance, then it will raise osmotic pressure and is called the   osmole.

Most molecules have a sigma of  (1= impermeable and 0=permeable). If sigma is zero =   osmole (effective or ineffective)

Tonicity is   by
EFFECTIVE osmotic pressure

Dashed line indicates the following changes: a
decreased ECF   &   and
increased ICF   & decreased ICF  

Fluid Shifts: Isotonic NaCl addition to ECF
-Adding   to   equivalent to amount administered

When fluid lost, add   in form of  solution

Fluid Shifts: Hypotonic NaCl addition to ECF
New lowered
 of
both
compartments. Add   NaCl
solution.

Fluid Shifts: Hypotonic NaCl addition to ECF

New lowered   of both
compartments, this reduced osmolarity of
ECF causing fluids to move
into  = reduced 
initially that will equilibrate
with   and
 in both.

Fluid Shifts: Hypertonic NaCl addition to ECF
-New  
osmolarity of
both
compartments
-This increased  
of ECF will pull fluids out
from ICF = increased
  and decreased  
at osmotic equilibrium

Isomitic volume contraction occurs when body fluids like   are lost

A decrease in ECF volume is due to  

What happens to a person with diarrhea for 24 hours?
Step 1: What changes are occurring in the ECF?  solution loss
Step 2: What changes are happening to ECF osmolarity? 
Step 3: If there is a change is ECF osmolarity, what direction is the shift?  

A hyperosmotic volume contaction occurs if there is  

Dehydration
Step 1: What changes are occurring in the ECF?   solution loss
Step 2: What changes are happening to ECF osmolarity?  
Step 3: If there is a change is ECF osmolarity, what direction is the shift?  will
decrease because   osmolarity increased

In hypersomotic volume contraction, the ECF and ICF volume decrease and the   and  

Hyposomotic conditions are created if a person has a condition that decreases   in the ECF ( ) and decreases   ( )

Volume Contraction Hypoosmotic
Step 1: What changes are occurring in the ECF? Loss of a  
Step 2: What changes are happening to ECF osmolarity?  
Step 3: If there is a change is ECF osmolarity, what direction is the shift?   will
increase because  osmolarity decreased

Volume Expansion: Isomotic
-Done by adding   to normal person
Step 1: What changes are occurring in the ECF? Adding an   solution
Step 2: What changes are happening to ECF osmolarity?  
Step 3: If there is a change is ECF osmolarity, what direction is the shift? N/A

Volume Expanision:  
-Occurs when a person has a hyndrome with inappropriate  
Step 1: What changes are occurring in the ECF? 
Step 2: What changes are happening to ECF osmolarity?  
Step 3: If there is a change is ECF osmolarity, what direction is the shift?   will
increase because of the decrease in   osmolarity

A hyperosmotic patient will need a   fluid replacement to
restore   volume (0.45% NaCl or 5% dextrose in water)- )-
following appropriate algorithms.

A person who lost   fluid, will only need equal isotonic fluid
replacement

A hypoosmotic patient will need a   solution to replace
contracted volume. (3% or 5% NaCl)- following appropriate
algorithms.

If you attempt to correct body fluid with just water, what happens?

Colloids correct intravascular volume by increasing osmotic pressure by pulling water from intersittial space (  forces)