Exam3Lec1FluidCompartments Flashcards
What is Total Body Water (TBW)?
The total amount of water in an individiuals body
TBW makes up what percentage of body weight for an average person and how many Liters in the body?
60% and 42 kg/42 L
how much water we have in our body
Which tissue(s) have most of our bodies H20?
Skin and Muscle
Muscle: 76% H2O, 41.7% body weight, 22.1 L of H2O
Skin: 76% H20, 19% body weight 9.1 L H20
How is the 42 L TBW (60% of body weight) separated in the body?
Separated into the:
1. Intracellular fluid
2. Extracellular fluid (plasma and intersitial fluid)
TBW=ECF + ICF
State the % body weight and amount of Liters of water in each compartment
A. ICF
B. ECF
C. Plasma
D. Interstial
A. ICF: 40% of Body Weight
28L of water
B. ECF: 20% of body weight
14 L of H2O
C. Plasma: 4-5 % body weight, 25% of ECF
D. Interstitial: 75% of ECF
ECF=intersitial + plasma
What seperates the ECF from ICF?
Cell membrane
What seperates the interstitial fluid and plasma in the ECF?
Capillary wall
more permeable than cell membrane
In the ICF, where is the water distributed and include the amount?
ICF (28 L of H2O)
Intracellular fluid=24 L
Bone=3 L
Transcellular fluid=1 L
In the ECF, where is the water distributed and include the amount?
ECF (14 L of H2O)
ISF and Lymph= 8 L
Plasma=3 L
Connective Tissue ISF=3 L
What is the only way to access and measure major fluid compartments in the body?
Through the plasma
What is used as a marker to measure TBW?
Water specifically H+ isotopes (ex. deuterium, tritium)
inject deutorium labeled H20 and wait until it equilibriates w/ other compartment to determine compoartment volumes
How are MOST fluid compartments measured?
The Standard Equation:
Compartment Volume= Amount injected/Final concentration
inject marker then measure volume in that compartment
For the compartments listed, what substance and equation is used to measure size?
- TBW
- ECF
- Plasma
- Blood
- TBW: HTO & D2O, Standard Equation
- ECF: Inulin & Radio-sodium; Standard Equation
- Plasma: 131 I-albumin & Evans Blue; Standard Equation
- Blood: 51 Cr-RBCs; Standard Equation
For the compartments listed, how are they measured (include equation)?
1. Interstitial
2. ICF
- Interstitial: Indirect; ECF-Plasma
- ICF: Indirect; TBW-ECF
What is the difference betweem mEq/L (mOsm/L) and mmol/L of plasma electrolytes
mEq/L or mOsm/L takes charge into account. SO its measuring osmoles of particles.
mmol/l is measuring molarity of solute (mole of a solute)
What is the normal plasma osmolarity
300 mOsmoles/L of H20
What is Osmolarity?
Distinct from molarity. It measures osmoles of solute particles rather than mole of solute. The distinction is made when the compound can dissociate in solution (H2O)
What is the Osmolarity (molar concentration) Equation?
Osmolarity (molar conc.)= # atoms or charge of ions x mmol/L
What is Osmole?
A unit of osmotic pressure equivalent to the amount of solute that dissociate in solution to form one mole of particles
1 mole NaCl=2 osmole because when NaCl is dissociated in solution (H2O) it becomes 1 osmole of Na and 1 osmole of Cl (2 osmole)
What is the difference between Osmolality and Osmolarity?
OsmoLALity: milimoles of solute/Kg of H2O
OsmoLARity: millmoles of solue/L of H2O
As Osmolality increases, what occurs to the H20 activity?
H20 activity decr
What does the Colligative Properties of Solution depend on and list the 4 properties
The number of molecules and not on their nature
1. Boiling Point
2. Freezing Point
3. Vapor Pressure
4. Osmotic Pressure
Using this image answer the following questions
1. Which compartment have higher osmotic pressure?
2. Which compartment does the H2O have the highest activity?
3. What is the direction of the water flow?
- A. the more particles the higher the osmotic pressure
- B. Activity of H2O increases as Osmolality decreases
- B to A. Move from high H2O activity to low H2O activity
Which cation has the highest concentraton in the ECF (Plasma & Interstitial fluid)?
Na+
Plasma: 142.0 mmoles/L
Interstitial fluid: 145.1 mmoles/L
major ECF cation
Which cation has the highest concentration in the ICF (Skeletal muscle cell)?
K+
Skeletal muscle cell: 140.0 mmoles/L
major ICF cation
Which anion has the highest concentration in the ECF (Plasma & Interstitial fluid)?
Cl-
Plasma: 114.0 mmoles/L
Interstitial fluid: 117.4 mmoles/L
major ECF anion
Which anion has the highest concentration in the ICF (Skeletal muscle cell)?
HPO42-, H2PO4
Skeletal muscle cell: 40.0 mmoles/L
What is the role of HCO3- in the ECF?
Major buffer system in the ECF to mediate blood pH
What is the role of H2PO42- (H2PO4) in the ICF?
Buffer system; Used for force in the skeletal muscle cells
What is the Na+ and K+ concentrations intracellularly and in the capillaries?
Intracellular:** LOW Na+** (10 mM), HIGH K+ (140 mM)
Capillary: HIGH Na+ (140 mM), LOW K+ (4.5 mM)
Is the capillary permeable or impermeable?
Permeable to most solutes, BUT impermeable to large proteins
Is the Intracellular compartment impermeable or permeable ?
Intracellular compartments are imperable to most solutes
What is the Darrow-Yannet Diagram?
A graph that shows the osmolality and volume changes of body fluids in the different compartments
high yield
What is the principal determinant of extracellular and intravascular fluid volume?
Total body content of sodium
water follows solute
If you inject D5W, Na+ & anions (Cl-) goes to which fluid compartment?
Extracellular fluid
If you inject D5W, K+ & anions (HPO42-) goes to which fluid compartment?
Intracellular fluid
If you inject D5W, D5W (5% of glucose in water) goes to which fluid compartment?
None, adds no effective osmole
just giving extra water so only volume incr
At equilibrium, osmolality is the ________ in all compartments
Same
What is the equation used to calculated volume of fluid compartments?
Volume=Total osmoles/osmolality=Tosm/Osm
Problem 1:
We infuse 1 liter of D5W (5% Dextrose in water).
- How many total osmoles have been infused?
- What is the new osmolality after infusion?
- What is the new volume for TBW, ECF, and ICF?
- What is the new total osmoles for the TBW, ECF, and ICF?
- 0 osmoles infused because glucose (D5) is metabolized
- 293 b/c solution was diluted b/c we added 1 L of H2O
- TBW=43, ECF=14.33 (1/3 of TBW), ICF=28.67 (2/3 of TBW)
- TBW, ECF, ICF=293 osmoles (osmalaroty stays the same throughout compartments)
What does this darrow yannet diagram represent?
Addition of 1 L of H20
Osmlality decreases b/c dilution b/c addition of water
ECF volume increases
ICF volume increases
Problem 2:
We infuse 1 liter of normal saline (0.9%) of 0.150 M
- How many total osmoles have been infused?
- What is the new osmolality after infusion?
- What is the new volume for TBW, ECF, and ICF?
- What is the new total osmoles for the TBW, ECF, and ICF?
- 300 total osmoles (150mM Na+ + 150mM Cl-)
- 300 b/c 300 osmoles being infused
- TBW=43 L, ECF=15 L, ICF=28 L
- TBW=129600, ECF=4500, ICF=3400
this is an ISOTONIC solution, normal amt of saline (9g of sodium chloride in 1L of water)
NOTE: Na+ and Cl- goeas to ECF so all the 300 infused osmoles goes to ECF b/c ISOTONIC
What does this darrow yannet diagram represent?
added 1L of normal saline (0.9 %) or 0.150M
Osmolality stays the same @ 300 osmoles
ECF increases by 1L since all the saline solution goes to the ECF
ICF stays the same
Problem 3:
We infuse 2 liters of 0.45% solution of NaCl
- How many total osmoles have been infused?
- What is the new osmolality after infusion?
- What is the new volume for TBW, ECF, and ICF?
- What is the new total osmoles for the TBW, ECF, and ICF?
- 300 total osmoles have been infused
- 293 from dividing the Tosm/vol of the TBW (12900/44)
- TBW= 44, ECF=15.3, ICF=28.7
- TBW=12900, ECF= 4500, ICF= 8400 (TBW & ECF increase by 300, while ICF stays the same)
NOTE: This is a HYPOTONIC solution
Which fluid compartments will increase the most if you infuse KCl?
a. Plasma
b. Interstitial
c. ECF
d. ICF
D. ICF bc K+ has high concentration outside so it moves inside
Which body systems are fluids commonly lost?
- GI
- Skin
- Blood
If you lose a lot of fluid, you generally lose a lot of Na+ and Cl- (ECF) and K+ and HCO3- (ICF), which structure is the exception where it doesnt lose any HCO3-
Gastric juice
most ions in ECF w/ gastric juice
Vomiting causes the loss of ________
Protons (b/c of HCl)
loose a lot of gastric
Diarrhea causes the loss of ________
bicarbonate (HCO3-)
loose ECF mostly
Why are infants more sensitive to dehydration?
They have higher H20 turnover and they have less TBW
Average weight: 3 kg
TBW: 2.3 L (77% body weight)
Turnover: 0.375
% TBW: 16 (1/6)
Which diease is associated with the Darrow-Yannet Diagram below?
Volume Contraction
- Diarrhea
- lose H2O and solutes, decrease volume w/ same osmolality
Which disease is associated with the Darrow-Yannet Diagram below?
Volume Contraction
- Water deprivation
- decreases H2O, more solute and not diluted= increases osmoles (more osmoles than H2O)
Which diease is associated with the Darrow-Yannet Diagram below?
Volume Contraction
- Adrenal insufficiency
- lose Na+ here, H2O move to ICF to keep osmolality the same
80 year old male with AD-over medicated because of irritability and has had nothing to drink for 3 days. What IV solution would you give to the 80 year old who has had nothing to drink for 3 days?
a. D5W
b. Normal Saline
c. 1/3 Normal Saline
d. Blood
e. Plasma
a. D5W
b/c dehydration (did not loose or gain sodium)
replenish H20 to lower osmolarity and incr volume
3 week old infant with vomiting and diarrhea for 2 days. What IV solution would you give to the infant with vomiting and diarrhea for 2 days?
a. D5W
b. Normal Saline
c. 1/3 Normal Saline
d. Blood
e. Plasma
b. Normal saline
lost mostly ECF
Gunshot wound-loss of 2 liters of blood. What IV solution would you give to the gunshot wound victim?
a. D5W
b. Normal Saline
c. 1/3 Normal Saline
d. Blood
e. Plasma
d.Blood & e. Plasma
True or False: ECF is 2/3 of total body water (TBW)
False, it’s ICF
True or False: The major ECF cation is Na+
True
True or False: A normal saline infusion incr ECF volume but decreases ICF volume
False, expands both ecf, icf stays the same
True or False: Hypertonic NaCl infusion incr ECF volume but decr ICF volume
True
True or False: Plasma volume=the distribution of water minus the distribution of Na+
False
