Body Fluid Compartments

Question 1

What percent of total body weight is solids?

Answer 1

40%

Question 2

What percent of body weight (BW) equals total body water (TBW)?

Answer 2

60%

Question 3

What percent of BW = intracellular fluid (ICF)?

Answer 3

40%

Question 4

What percent of BW = extracellular fluid (ECF)?

Answer 4

20%

Question 5

What percent of ECF = interstitial fluid (ISF)

Answer 5

75%

Question 6

What percent of ECF = plasma?
What percent of plasma = venous?
What percent of plasma = effective circulating volume?

Answer 6

25%

80%

20%

Question 7

Probably just a good idea to draw the picture on the test.

Answer 7

DRAW THE DANG PICTURE

Question 8

What is volume of distribution of a drug?

What is it used for?

Answer 8

Reflection of how a drug will distribute in the body.
The volume of plasma that would be necessary to account for the total amount of drug in the patient’s body, if found in the same concentration as the plasma.
Used in calculating loading doses and TBW.

Question 9

What are the 4 levels of Vd (volume of distribution)?

Answer 9

<3 L = Drug only in plasma
14 L = Drug in plasma and ECF (interstitial fluid)
40-45 L = Drug in TBW
> 45 L = Drug widely distributed in TBW and tissues (i.e. bone)

Question 10

Name two systems that bring water/nutrients into the body?

Answer 10

GI and carbohydrate metabolism.

Question 11

Name 5 systems do output of water?

Answer 11

Kidneys, lungs, feces, sweat, skin

Question 12

Major XC cations and anions.

Answer 12

Na+ and Cl-

Question 13

Major IC cations and anions.

Answer 13

K+ and PO4- (and organic anions)

Question 14

What is the pressure generated by large molecules (like proteins) in solution that are impermeable to membranes?

Answer 14

Oncotic (colloid osmotic) pressure

Question 15

What do you use to find these values experimentally? 
TBW? 
ECF?
ICF?
Plasma Volume? 
Interstitial fluid?

Answer 15

Utilize the indicator that remains within the compartment you want to evaluate.
TBW: radioactive H2O, antipyrine
ECF: radioactive Na, inulin
ICF: TBW - ECF = ICF
Plasma volume: albumin, evans blue dye (binds albumin)
Interstitial fluid: ECF - Plasma = ISF

Question 16

What is the gibbs-donnan effect?

What is the normal Na+ and K+ osmolality?

Answer 16

The negative charge of proteins within the vasculature brings the Na+ and K+ slightly higher than expected.
290 mOsm

Question 17

Finish the sentence. Where Na+ goes …

Answer 17

Water follows

Question 18

How do you quickly estimate plasma osmolality?

Answer 18

2[Na+]

Question 19

What’s the full plasma osmolality equation?

When is this unreliable?

Answer 19

2]Na+] + (glucose/18) + (urea/2.8)

In diabetes or kidney failure (too much glucose or urea)

Question 20

What is highly permeable between ECF and ICF?

Answer 20

Water

Question 21

Fluid distribution of the ECF compartments is due to what?

Answer 21

Starling forces

Question 22

What is the force that favors filtration?

Opposes filtration?

Answer 22

Capillary hydrostatic pressure

Colloid osmotic (oncotic) pressure

Question 23

What is the equation for capillary filtration? (Starling forces)

Answer 23

Capillary filtration = K(f) * (Pc-Pif) - (pi(c) - pi(if))

Question 24

All solutes and water that enter or leave the body do so via?

Answer 24

The ECF

Question 25

What happens to the following variables when water loss (dehydration) occurs?
ECF?
ICF?
ECF mOsm?
ICF mOsm?

Answer 25

ECF = Decrease

ICF = Decrease

ECF mOsm = Increase

ICF mOsm = Increase

Question 26

What is the difference between crystalloid and colloid fluids? What are they used for?

Answer 26

Water therapy.

Crystalloid = electrolytes and stay in the ECF (saline)
Colloid = proteins and large molecules that stay in vascular space (dextran, albumin)