Body fluid

Question 1

Divi up the total body water

Answer 1

60/40/20.
60% of wt is TBW = 42L
40% of wt is ICF
20% of wt is ECF
ECF = 3/4 interstitial + 1/4 plasma

Question 2

What’s the “dilution principle”?

Answer 2

We are able to determine fluid volume based on measuring the amount of solute and then its concentration after it has diffused.

Question 3

If your patient has an acute change in body weight over a brief period of time, what is most likely causing this change?

Answer 3

change in TBW

Question 4

the mEq of a fluid compartment is based on _______________

Answer 4

Valence charges

Na+ = 1mEq, where Ca++ = 2mEq

Question 5

Since all fluid compartments are electrically neutral, what does the body do to compensate when you have a higher humber of mEq’s in one compartment?

Answer 5

Balances with proteins (negative charge)

Intracellularly, you have more Ca++ and Mg++, so you also have more protein to balance

Question 6

__________________ is the concentration of discrete, osmotically active particles in solution.

Answer 6

Osmolality. (mOsm/kgg H2O)

Particle mass, charge, and size do NOT matter

Question 7

True or False: Body fluid compartments are in osmotic equilibrium.

Answer 7

True

Question 8

What is a normal osmolality?

Answer 8

275-300mOsm/kg H2O. (Typically use 290)

Question 9

The volume of fluid compartments depends on _____________

Answer 9

of osmotically active particles

Question 10

If you add pure water to the body, what happens to it, and what happens to your osmolality?

Answer 10

Both ICF and ECF expand, Osm falls

Question 11

If you add isotonic NaCl to your body, what happens to the fluid compartments? What happens to osmolality?

Answer 11

Only the ECF expands, no change in Osm

Question 12

If you add pure NaCl to your body, what happens to the fluid compartments? What happens to osmolality?

Answer 12

The ECF expands, the ICF shrinks and Osm increases.

Question 13

The plasma osmotic pressure is __________the osmotic pressure of the interstitium. Why?

(less than, equal to, greater than)

Answer 13

greater than! This is due to the hydrostatic pressure in the blood vessels which offsets this osmotic pressure difference

Question 14

Explain the Starling Hypothesis

Answer 14

Hydrostatic pressure in the capillaries is bigger on the arterial side and pushes fluids out of the capillaries. Eventually, there’s not so much fluid volume in the capillaries, but still lots of solute. So the osmotic pressure pulls water back into the capillaries on the venous side.

Question 15

________ is abnormal expansion of the interstitial fluid compartment

Answer 15

edema

Question 16

If you notice localized edema in your patient, what is the cause?

Answer 16

Starling’s forces are unbalanced. Fluids are moving into the interstitium, but not being pulled back in.

(ex: DM pts have low protein, so no proteins to create osmotic pressure)

Question 17

If you notice generalized edema in your patient, what is the cause?

Answer 17

Kidneys aren’t excreting NaCl. (water follows salt due to osmotic principles)