Body Fluid Compartments Flashcards
Total body water (TBW)
- Equation?
- Normal value?
.6 x body weight
normal is 42 L
Total body water is divided up into?
-Extracellular fluid (ECF)
-Intracellular fluid (ICF)
divided by the cell membrane
Extracellular fluid (ECF)
- Equation?
- Normal value?
.2 x body weight
normal is 14 L
Intracellular fluid (ICF)
- Equation?
- Normal value?
.4 x body weight
Normal is 28 L
Extracellular fluid can be divided into?
- Interstitial fluid
- Plasma
Interstitial fluid
- Equation?
- Normal value?
.75 x ECF
normal is 10.5 L
Plasma
- Equation?
- Normal value?
.25 x ECF
Normal is 3.5 L
What separates the interstitial fluid from the plasma?
Capillary wall
The plasma can be divided into?
- Venous (compliance)
- Arterial
Venous
- Equation?
- Normal value?
.8 x plasma
-normal is 2.8 L
If blood volume is low, what happens to the blood that you do have?
It is shunted toward the more important organs (brain and kidneys) to protect them
Arterial
- Equation?
- Normal value?
.2 x plasma
Normal is .7 L
Arterial is also known as?
-What does this mean?
Effective Circulating Volume (ECV)
-Volume of arterial blood EFFECTIVELY PERFUSING TISSUE
Transcellular fluid
- Also included in the ECF
- It normally contains only a small amount of water such as epithelial secretions, synovial fluid, CSF, etc
- It is said to occupy a “third space” (i.e. 3 ECF compartments)
- Overabundance of fluid in third space can be pathologic
Hypovolemia due to vomiting -ECV? -ECF? -Plasma volume? -Cardiac output? -
- ECV-decreased
- ECF-decreased
- Plasma volume-decreased
- Cardiac output-decreased
Heart failure
- ECV?
- ECF?
- Plasma volume?
- Cardiac output?
- ECV-decreased
- ECF-increased
- Plasma volume-increased
- Cardiac output-decreased
Arteriovenous fistula
- ECV?
- ECF?
- Plasma volume?
- Cardiac output?
- ECV-normal
- ECF-increased
- Plasma volume-increased
- Cardiac output-increased
Severe Hepatic Cirrhosis
- ECV?
- ECF?
- Plasma volume?
- Cardiac output?
- ECV-decreased
- ECF-increased
- Plasma volume-increased
- Cardiac output-normal/increased
Clinical relevance of body fluid compartments
-Pharmacology-Volume of distribution (Vd) of a drug
- Apparent volume of body fluid in which the total dose of the drug is distributed at the same concentration as in the plasma
- Useful in calculating loading doses
If the Vd is less than or equal to 3L what compartment is the drug distributed in?
Drug is only in the plasma
If the Vd is 14L what compartment is the drug distributed in?
The drug is in the ECF (plasma and interstitial fluid)
If the Vd is 40-45L what compartment is the drug distributed in?
The drug occupies the total body water
If the Vd is is greater than 45L what compartment is the drug distributed in?
The drug is widely distributed and bound in body tissues
Normal daily urine output?
1400 mL
Donnan effect
Albumin is very large and negative so it attracts positively charged Na and K ions
Non-electrolytes
- Protein levels in ICF and intravascular compartments?
- Protein levels in interstitial fluid
- Higher protein levels in ICF and intravascular compartments (primarily albumin)
- Lower in interstitial fluid
Non-electrolytes
-Oncotic (osmotic?) pressure
Proteins normally do not move (membranes are impermeable to proteins), therefore they do not normally impact osmolarity but do exert oncotic pressure
-Osmotic pressure generated by large molecules (proteins) in solution which are impermeable to membranes
Volumes- indicator/dilution methods-slide 13
-Not sure if we need to know this
?
Balance of ions
-Normally, osmolarity is balanced between?
- Interstitial and intravascular fluids (ECF compartments)
- ECF and ICF
Balance of ions
-Na and K concentration is slightly higher than expected due to?
Donnan effect