3. Body Fluid Compartments

Question 1

ECF is calculated by taking 0.2 times the body weight. What can the ECF be further divided into?

Answer 1

Interstial fluid (0.75 x ECF)
Plasma (0.25 x ECF)

Question 2

Plasma is the only fluid that can be acted on directly to control its volume and composition… so this means any control mechanism that operates on plasma in effect regulates what?

Answer 2

the entire ECF

Question 3

Water added to the body fluids enters ____ compartment first and fluid always leaves the body via _____

Answer 3

ECF , ECF!

Question 4

What are the main outputs for fluid? (5)

Answer 4

kidneys
lungs
feces
sweat
skin

Question 5

The normal intake of fluids is 2100 ingested and 200 from metabolism, equaling 2300. What is the typical output?

Answer 5

2300 via kidneys, lungs, feces, sweat, and skin

Question 6

During heavy excercis, what is the total output of fluids?

Answer 6

6600ml

Question 7

What is it called when too much fluid shifts from the blood vessels (intravascular) into the nonfunctional area of cells? (fluid is trapped between tissues and organs of the abdomen-ascites, interstitial area around lungs-pulmonary edema, often due to burns)

Answer 7

Third spacing- this is problematic d/t fluid being lost from intravascular space

Question 8

It is important to remember solutes do not travel from one side to another. Water moves through a semipermeable membrane from higher concentration of water (lower [solute], more diluted solution) to ?

Answer 8

lower concentration of water (with a higher [solute], more concentrated solution)

Question 9

Why are the concentrations of Na high in the ECF and K+ high in the ICF?

Answer 9

Due to the Na/K ATPase, which pumps 3Na out and 2K in

Question 10

What are the primary cations for the ECF and ICF?

Answer 10

ECF is Na and ICF is K+

Question 11

Nonelectrolytes have covalent bonds that prevent them from dissociating in solution and have no charge. What about electrolytes?

Answer 11

Dissociate into ions in water Ex: NaCl = Na + Cl, MgCl2 = Mg + Cl + Cl

• greater ability to cause fluid shift *

Question 12

What is the measure of the number of osmotically active particles per Kg of H20?

Answer 12

osmolality

Question 13

What is the number of osmotically active particles per liter of total solution?

Answer 13

Osmolarity (interchangable with osmolality)

Question 14

The ECF in blood consists of 60% of the total, including plasma, WBC and platelets. The ICF in the blood consists of?

Answer 14

40% and mainly the red blood cells

Question 15

An ECF volume loss will result in what regarding plasma?

Answer 15

increased total plasma protein (concentration)

Question 16

An ECF volume gain will result in what regarding plasma?

Answer 16

decreased total plasma protein (diluted)

Question 17

The normal hematocrit for men is 0.40 and for women is 0.36. (calculated by height of RBCs/ total height) What is the hematocrit for people with anemia?

Answer 17

0.10 which is barely sufficient to sustain life

Question 18

If ECF volume is lost or ICF volume is gained this would lead to what regarding hematocrit?

Answer 18

an increase in hematocrit (concentrated ECF/swelling RBC)

Question 19

If ECF volume is gained or ICF volume is lost, this would lead to what regarding hematocrit?

Answer 19

a decrease in hematocrit (diluted ECF/shrunk RBC)

Question 20

A more accurate way to measure fluid compartments is by using an indicator/marker that will occupy the compartment you want to measure and only that compartment. What are the most commonly used indicators to measure ECF (1), TBW (1), and Plasma V (1)?

Answer 20

Inulin for ECF
H202/3 for TBW
125I-albumin for plasma volume

Question 21

What will happen to ecf volume, osmolarity and icf volume and osmolarity if you sweat 3 liters and drink 3 liters of h20?

Answer 21

ic volume increases d/t increase in h20
ic osmolarity decreases d/t increase V- diluted
ec volume decreases because goes to ic
ec osmolarity decreases d/t lost of salt in sweat

Question 22

Negatively charged ions (anions) create two events.
1. protein particles create an oncotic gradient favoring movement into cell
2. negative charges on proteins create and electrical gradient, favoring movement into cell.
What is this effect?

Answer 22

Gibbs-Donnan effect: which states how negative charged proteins on one side of a semipermable membrane generates both osmotic and electrochemical gradients

Question 23

How is the gibbs-donnan effect countered? (if it was not countered there would be endless influx of water into the cell, resulting in swelling and cell death)

Answer 23

via the Na/K ATPase, 3Na out and 2K in, keeping sodium outside of the cell so it doesnt swell, preventing excessive influx of water

Question 24

What are the two factors that make the free movement of fluid possible?

Answer 24

1. water molecules diffuse through capillary walls faster than blood
2. there is a pressure difference between the inside and outside of the vessels (cap filtration pressure)

Question 25

What would cause more filtration and the hydrostatic capillary pressure to increase?

Answer 25

increase blood flow/BP would increase the amount of filtration and increase the hydrostatic capillary pressure

Question 26

usually in the arterioles there is filtration and what mainly occurs in the venules?

Answer 26

absorption

Question 27

What pressure is referred to as the osmotic pulling force of albumin or any larger negative protein in the intravascular space which attracts water and holds it inside the blood vessel?

Answer 27

plasma colloid osmotic pressure

Question 28

The first main cause of edema is by alteration in capillary hemodynamics- fluid moves from vascular space into the interstitium. the second main cause is?

Answer 28

Renal retention of dietary Na+ and water expansion of ECF volume, usually results in hypertension.

Question 29

What type of cell has a NaCl solution concentration equal to 0.9% and if cells are placed in this solution, there will be equal movement of water in and out?

Answer 29

Isotonic solution

Question 30

What type of cell has a nacl soltion concentration greater than 0.9% and if cells are place in this solution there will be a net movement of water out of the cell causing it to shrink?

Answer 30

Hypertonic solution

Question 31

What type of cell has a nacl solution concentration lesser than 0.9% and if cells are placed in this solution there will be a net movement of water into the cell cause it to swell?

Answer 31

Hypotonic solution

Question 32

There are two types of replacement therapies for when someone is dehydrated. One is crystalloids and one is colloids. What are crystalloids?

Answer 32

contain organic salts in sterile water, more commonly glucose and NaCl. Crystalloids do not cross plasma membranes and stay in the ECF

Question 33

What are colloids?

Answer 33

contain large molecules that do no pass through membranes. They remain in intravascular compartment and expand the plasma volume by drawing fluid from extravascular space

Question 34

Plasma osmolality is equal to ?

Answer 34

2(plasma [Na+] )

Question 35

When there are changes in Na balance it leads to a change in the volume status. When there is a change in the H20 balance, this leads to a change in?

Answer 35

Na concentration and osmolarity

Question 36

Dehydration can be divided according to serum sodium concentration into what two categories?

Answer 36

hypernatremic and hyponatremic dehydration

Question 37

Hyponatremic or hypotonic dehydration occurs when the loss of sodium is greater than the loss of water in the ECF. serum sodium concentration in the ICF is greater than ECF so what occurs?

Answer 37

ECF water goes to icf to establish equilibrium, leaving the serum sodium and osmolality in ecf less than normal range (130-150)

Question 38

Hypertonic/Hypernatremic dehydration occurs when loss of h20 is greater than the loss of sodium in the ecf. so what occurs?

Answer 38

water shifts from the icf to the ecf, serum osmolality is greater than 300 and serum sodium is more than 150

Question 39

What type of fluid shift disturbance causes a decrease in ecf volume which causes decreased blood volume and decreased blood pressure?

Answer 39

volume contraction

Question 40

What type of fluid shift disturbance causes a increase in ecf volume which causes volume expansion, edema and increased bp?

Answer 40

volume expansion

Question 41

Isosmotic means there is no change in body fluid osmolarity. Hyperosmotic means body fluid osmolarity is increased while hyposmotic means ?

Answer 41

body fluid osmolarity is decreased

Question 42

What occurs during iso-osmotic volume contraction during acute fluid loss condition like hemorrhage, diarrhea and vomiting?

Answer 42

decrease in ECF volume and no change in body osmolality or ICF volume

Question 43

What occurs during hyper-osmotic volume contraction during hypotonic fluid loss conditions like dehydration, diabetes, and alcoholism?

Answer 43

there is a decrease in ecf and icf volume, however the solute stays in the body so the osmolarity/concentration will increase in both

Question 44

What occurs during iso-osmotic volume expansion like during a gain of isotonic saline solution?

Answer 44

increase in ecf volume and no change in osmolality or icf volume

Question 45

What occurs during hypo-osmotic volume expansion like during excess water drinking and syndrome of ADH? (gain of hypotonic fluid)

Answer 45

the icf and ecf volume will increase but the icf and ecf osmolality will decrease

Question 46

How would you calculate the concentration and volume of each compartment given weight and plasma osmolarity?

Answer 46

ecf = 0.2 x body weight = volume icf= 0.4 x body weight = volume icf v + ecf v = TBW icf v x plasma molarity = concentration icf ecf v x plasma molarity = concentration ecf