Body Fluids

Question 1

TBW

Answer 1

About 60% of body weight

Question 2

ICF

Answer 2

40% of body weight
2/3 TBW

Question 3

ECF

Answer 3

20% of body weight
1/3 of TBW
ISF + blood plasma
About 1 L in humans

Question 4

ISF

Answer 4

15% of body weight
75% of ECF

Question 5

Blood plasma

Answer 5

5% of body weight
Contains various proteins while other compartments don’t
25% of ECF

Question 6

Hematocrit

Answer 6

Proportion of blood volume made up by RBC
About 45% in men, 40% in women

Question 7

Total blood volume calculation

Answer 7

Plasma volume + (TBV * Htc)

OR

TBV = .75 x body weight

Question 8

Indicator dilution method

Answer 8

Putting dyes that isolate to one compartment to measure volume

Question 9

Volume calculation (w/ dye)

Answer 9

Amount of dye (- excreted amount) / diluted concentration of dye

Question 10

TBW indicators

Answer 10

Heavy water
Antipyrine

Question 11

ECF indicators

Answer 11

Na, mannitol, inulin, l-iothalamate

Question 12

Plasma

Answer 12

I-albumin
Evans blue dye

Question 13

Ions higher extracellularly

Answer 13

Na (!), Cl, Ca, HCO3

Question 14

Ions higher intracellularly

Answer 14

K (!), Mg

Question 15

Calcium

Answer 15

Very low intracellular, highest concentration gradient, would flow from ECF to ICF

Question 16

pH gradient

Answer 16

ICF is more acidic, 2x [H+]
ICF = 7.0
ECF = 7.4

Question 17

Protein distribution

Answer 17

Should be no proteins ISF, only ICF and plasma

Question 18

Electroneutrality

Answer 18

Each compartment is electroneutral - # of cations = anions but can be different across membrane

Question 19

Hyperosmotic to ICF

Answer 19

Cell shrinks because water flows out

Question 20

Idealized semi-permeable membrane

Answer 20

Membrane is permeable to water but not molecules so only osmosis

Question 21

Isoosmotic to ICF

Answer 21

No change

Question 22

Hypoosmotic to ICF

Answer 22

Cell swells because water flows in

Question 23

Osmolarity of ICF and ECF

Answer 23

EQUAL, around 280-300 mOsm/L

Question 24

Osmolarity equation

Answer 24

Molarity x number of molecules

Molarity = mass / MW

Question 25

Effective osmolarity

Answer 25

Only considers impermeant solutes

Question 26

Osmotic pressure

Answer 26

Water moves to more solute concentrated side - if you want it to stop, apply osmotic pressure to that side

Question 27

Tonicity vs osmolarity

Answer 27

Tonicity only considers impermeant solutes/effective osmolarity

Question 28

Plasma oncotic pressure (πc)

Answer 28

Pushes water into plasma/capillaries Caused by proteinsin plasma

Question 29

Plasma hydrostatic pressure (Pisf)

Answer 29

Pushes fluid into capillaries

Question 30

Hydrostatic pressure in capillaries (Pc)

Answer 30

Pushes fluid into ISF Strongest force

Question 31

Oncotic pressure in capillaries (πisf)

Answer 31

Pushes fluid into ISF Weakest, usually ignored

Question 32

Net driving force

Answer 32

Pc - πc - Pisf + πisf

Question 32

Na-K ATPases

Answer 32

Maintain ion gradient Na OUT, K in (against gradient)

Question 33

Isoosmotic volume contraction

Answer 33

Water loss and electrolytes loss in ECF are proportional Caused by diarrhea or vomiting

Question 34

Hyperosmotic/hypertonic volume contraction

Answer 34

Caused by dehydration - sweating, fever, diabetes insipidus (decreased ADH, dilute urine)

Question 35

Hypoosmotic volume contraction

Answer 35

Water loss in ECF < electrolytes loss in ECF Caused by adrenal insufficiency, low aldosterone, very low bp, salt craving

Question 36

Isoosmotic volume expansion

Answer 36

Proportional water and electrolytes gain in ECF Caused by isotonic NaCl infusion

Question 37

Hypoosmotic volume Expansion

Answer 37

Water gain > electrolytes gain Caused by syndrome of inappropriate ADH - water retention - hyponatremia transiently

Question 37

Hyperosmotic volume expansion

Answer 37

Water gain < electrolytes gain Caused by hyponatremia - high NaCl intake, water retention

Question 38

Hypovolemia

Answer 38

Loss of water - volume contraction Increases [plasma protein] and plasma oncotic pressure

Question 39

Hypervolemia

Answer 39

Gain of water - volume expansion Decreases [plasma protein] and plasma oncotic pressure

Question 40

SIADH

Answer 40

ADH causes water retention - diluted plasma, dilute ECF Significantly increased in SIADH Causes hypo-osmotic volume expansion

Question 41

Diabetes insipidus

Answer 41

Extremely low ADH - dilute urine, concentrated ECF Hyperosmotic volume contraction

Question 42

Adrenal insufficiency

Answer 42

Aldosterone increases sodium and water in ECF Low aldosterone - very low sodium (water follows) Hypoosmotic volume contraction