Exam 3 Grid
Fluid and Electrolyte
1) Describe the composition of the major body fluid compartments.
o There are two fluid compartments
Extracellular Fluid (ECF) – fluid outside the cell
1/3 of the total body water
Includes the following
o Interstitial space (fluid between cells, “third space”)
o Blood, lymph, bone, and connective tissue water
o Transcellular fluid which includes cerebrospinal fluid, synovial
fluid, peritoneal fluid, and plural fluid
Intracellular Fluid (ICF) – fluid inside the cell
2/3 of the total body water
2) Describe the processes involved in regulating fluid and electrolyte balance
o Filtration
The movement of fluid (water) though a cell or blood vessel membrane due to
hydrostatic pressure differences on both sides of the membrane
Hydrostatic pressure is the pressure exerted by water molecules against the
surfaces of a confining space
When a pressure gradient exist, water movement through membranes
(filtration) occurs until hydrostatic pressure is the same on both sides
Fluid will always move from a space with a higher hydrostatic pressure to a
space with a lower hydrostatic pressure
For example, the hydrostatic pressure gradient between the capillary blood and
the interstitial space will determine if water leaves the blood vessels and enters
the tissues spaces or vice versa
Right sided heart failure causes an increase in the volume of blood in the right
ventricle which causes blood to back up in the venous and capillary system. This
excess amount of blood in the capillary system causes an increase in the
capillary hydrostatic pressure which leads to fluid moving to the interstitial
tissue space (due to the hydrostatic gradient) which forms visible edema
o Diffusion
The movement of particles (solute) across a permeable membrane from an area
of higher particle concentration to an area of lower particle concentration
Concentration gradient occurs when two fluid spaces have different
concentrations of the same type of particles
The cell membrane has selective permeability; it permits diffusion of some
particles but not others
ECF has 10X more sodium that the ICF
Glucose level can be much higher in the ECF compared to ICF, but glucose needs
assistance (insulin) to enter the cell. This type of diffusion is called facilitated
diffusion
, o Osmosis
The movement of water only across a semipermeable membrane to achieve an
equivalent of osmolarity
For osmolarity to occur, there must be a membrane that separate two fluid
spaces and once space must have particles that cannot move through the
membrane
Movement of water from higher water concentration side (lower solute
concentration) to the side with lower water concentration (higher solute
concentration)
The concentration equilibrium occurs by the movement of water molecules
rather than the movement of solute particles
The normal osmolarity value for plasma and other body fluids ranges between
270 to 300 mOsm/L – This is called isotonic
Fluids with osmolarity greater than 300 is called hypertonic
If a hypertonic solution is infused into a patient with normal ECF
osmolarity, this will make patient’s blood hypertonic.
The body will try to balance things out by pulling interstitial fluid and
intracellular fluid (ICF) into the circulation.
This will cause the interstitial and ICF volume to shrink and the plasma
volume to expand
Example of hypertonic solutions include 3% and 5% saline
o Fluids with osmolarity less than 270 is called hypotonic
If a hypotonic solution is infused into a patient with normal ECF osmolarity,
this will make patient’s blood hypotonic.
The body will try to balance things out by pulling fluid from the circulation
into the interstitial fluid and intracellular fluid (ICF)
This will cause the interstitial and ICF volume to expand and the plasma
volume to shrink
Example of hypertonic solutions include 0.45% saline
3) Describe common fluid, electrolyte imbalances.
Hypovolemia low blood volume (ex. Dehydration)
Hypervolemia high blood volume (ex. Fluid volume overload)
Sodium 135 - 145
Potassium 3.5 - 5
Calcium 9 - 10.5
Magnesium 1.8 - 2.6
Chlorine 98 - 106
Phosphate 3 – 4.5
4) Identify risk factors and complications of fluid and electrolyte imbalances.
Fluid imbalance risk factors
o Age
Older adult has less total body water than a young adult
o Gender
o Amount of fat
Fluid and Electrolyte
1) Describe the composition of the major body fluid compartments.
o There are two fluid compartments
Extracellular Fluid (ECF) – fluid outside the cell
1/3 of the total body water
Includes the following
o Interstitial space (fluid between cells, “third space”)
o Blood, lymph, bone, and connective tissue water
o Transcellular fluid which includes cerebrospinal fluid, synovial
fluid, peritoneal fluid, and plural fluid
Intracellular Fluid (ICF) – fluid inside the cell
2/3 of the total body water
2) Describe the processes involved in regulating fluid and electrolyte balance
o Filtration
The movement of fluid (water) though a cell or blood vessel membrane due to
hydrostatic pressure differences on both sides of the membrane
Hydrostatic pressure is the pressure exerted by water molecules against the
surfaces of a confining space
When a pressure gradient exist, water movement through membranes
(filtration) occurs until hydrostatic pressure is the same on both sides
Fluid will always move from a space with a higher hydrostatic pressure to a
space with a lower hydrostatic pressure
For example, the hydrostatic pressure gradient between the capillary blood and
the interstitial space will determine if water leaves the blood vessels and enters
the tissues spaces or vice versa
Right sided heart failure causes an increase in the volume of blood in the right
ventricle which causes blood to back up in the venous and capillary system. This
excess amount of blood in the capillary system causes an increase in the
capillary hydrostatic pressure which leads to fluid moving to the interstitial
tissue space (due to the hydrostatic gradient) which forms visible edema
o Diffusion
The movement of particles (solute) across a permeable membrane from an area
of higher particle concentration to an area of lower particle concentration
Concentration gradient occurs when two fluid spaces have different
concentrations of the same type of particles
The cell membrane has selective permeability; it permits diffusion of some
particles but not others
ECF has 10X more sodium that the ICF
Glucose level can be much higher in the ECF compared to ICF, but glucose needs
assistance (insulin) to enter the cell. This type of diffusion is called facilitated
diffusion
, o Osmosis
The movement of water only across a semipermeable membrane to achieve an
equivalent of osmolarity
For osmolarity to occur, there must be a membrane that separate two fluid
spaces and once space must have particles that cannot move through the
membrane
Movement of water from higher water concentration side (lower solute
concentration) to the side with lower water concentration (higher solute
concentration)
The concentration equilibrium occurs by the movement of water molecules
rather than the movement of solute particles
The normal osmolarity value for plasma and other body fluids ranges between
270 to 300 mOsm/L – This is called isotonic
Fluids with osmolarity greater than 300 is called hypertonic
If a hypertonic solution is infused into a patient with normal ECF
osmolarity, this will make patient’s blood hypertonic.
The body will try to balance things out by pulling interstitial fluid and
intracellular fluid (ICF) into the circulation.
This will cause the interstitial and ICF volume to shrink and the plasma
volume to expand
Example of hypertonic solutions include 3% and 5% saline
o Fluids with osmolarity less than 270 is called hypotonic
If a hypotonic solution is infused into a patient with normal ECF osmolarity,
this will make patient’s blood hypotonic.
The body will try to balance things out by pulling fluid from the circulation
into the interstitial fluid and intracellular fluid (ICF)
This will cause the interstitial and ICF volume to expand and the plasma
volume to shrink
Example of hypertonic solutions include 0.45% saline
3) Describe common fluid, electrolyte imbalances.
Hypovolemia low blood volume (ex. Dehydration)
Hypervolemia high blood volume (ex. Fluid volume overload)
Sodium 135 - 145
Potassium 3.5 - 5
Calcium 9 - 10.5
Magnesium 1.8 - 2.6
Chlorine 98 - 106
Phosphate 3 – 4.5
4) Identify risk factors and complications of fluid and electrolyte imbalances.
Fluid imbalance risk factors
o Age
Older adult has less total body water than a young adult
o Gender
o Amount of fat
