Body fluids

Question 1

What are the functions of body fluids?

Answer 1

Dissolve chemical substance
Transport insoluble fat after emulsification
Dissociation of substances to form ions
Act as medium for chemical reactions
Thermoregulation
Digestion and prevent constipation

Question 2

What is the average daily water intake and output? How are they related?

Answer 2

Fluids ingested - 2100 mL
From metabolism - 200 mL
Total - 2300 mL

Insensible: Skin - 350 mL
Insensible: Lungs - 350 mL
Sweat - 100 mL
Feces - 100 mL
Urine - 1400 mL
Total - 2300 mL

Input = output

Question 3

What is total body water and what causes it to vary?

Answer 3

60% of total body weight - average male has 42 L

Age, sex, percent body fat

Question 4

How are body fluids distributed?

Answer 4

20% body weight in ECF (about 14L) split into 10.5 L in interstitial fluid and 3.5 L in plasma

40% of body weight in ICF about 28 L

Question 5

What is the equation used in indicator dilution technique?

Answer 5

Vol B = (Vol A x Conc A) / Conc B

V = (Amount administered - excreted) / concentration in plasma
or V = i/c

Question 6

What does the indicator dilution technique assume?

Answer 6

Indicator disperses evenly, only in the compartment measured
Indicator is not metabolized or excreted - corrections can be made for loss

Question 7

What indicators can be used for total body water?

Answer 7

Tritium
Deuterium
Antipytine

Question 8

What indicators can be used for ECF?

Answer 8

22Na
125I-iothalamate
Thiosulfate
Inulin
Mannitol

Question 9

How do you calculate volume of ICF?

Answer 9

No indicators
Total body water - ECF

Question 10

What indicators can be used for plasma?

Answer 10

125I-albumin
Evans blue dye

Question 11

What indicator and equation can be used for blood volume?

Answer 11

51Cr-labeled RBCs
Blood volume=plasma volume/(1-hct)

Question 12

How do you calculate interstitial fluid?

Answer 12

ECF volume - plasma volume

Question 13

In what direction will osmosis take place?

Answer 13

From low solute concentration to high solute concentration

Question 14

What is an osmole?

Answer 14

Concentration of a solution in terms of number of particles

1 osmole = 1 gm molecular weight of non-dissociated solute

Question 15

What is osmotic pressure and its equation?

Answer 15

Pressure necessary to prevent solvent migration

Vant Hoff’s equation
P = nRT/V
P = osmotic pressure
n = number of particles
R = gas constant
T = absolute temp
V = volume of solution

Question 16

What is osmolarity and its equation?

Answer 16

Osmolarity = g x C
g = number of particles in solution (Osm/mol)
C = concentration in mol/L

Question 17

What is osmolality?

Answer 17

Concentration of osmotically active particles per Kg of solvent

Question 18

When is the body at osmotic equilibrium?

Answer 18

When plasma, ISF, and ICF all equal 300 mOsm

Question 19

What does isosmotic mean?

Answer 19

Two solutions with the same osmolarity

Question 20

What do we call two solutions with different osmolarities?

Answer 20

Hyperosmotic - for solution with higher osmolarity
Hyposmotic - for solution with lower osmolarity

Question 21

What is tonicity and how does it relate to osmolarity?

Answer 21

How a solution would affect cell volume if the cell was placed in that solution

compares osmolarity of a solution with plasma

Question 22

What is the definition of isotonic?

Answer 22

The same as plasma - no net water movement

Question 23

What is the definition of hypotonic and what occurs?

Answer 23

Less water in cell than plasma or higher conc of solutes in cell than in plasma
Cells swell leading to lysis

Question 24

What is the definition of hypertonic and what occurs?

Answer 24

Greater fluid in cell than plasma, or greater conc of solutes in plasma than in cell
Shrinkage/crenation of cell occurs

Question 25

What are factors that cause fluid movement between ICF and ECF?

Answer 25

Ingestion or renal retention of water
Dehydration
IV infusion of different types of solutions
Loss of large amounts of fluid from GI tract
Loss of abnormal amount of fluids from sweating or through the kidneys

Question 26

What are two basic principles of fluid movement?

Answer 26

Water moves rapidly across cell membranes
Cell membranes are almost completely impermeable to many solutes

Question 27

What is the method for analyzing fluid shift problems?

Answer 27

-Determine what is gained and/or lost
-Assume any loss or gain affects ECF first
-Predict change, if any, in ECF osmolarity
-Determine which way water must shift to each equal ICF and ECF osmolarities
-Predict directional changes for osmolarities, ICF volume, ECF volume, and total body water