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