Electrolyte and fluid balance- fluid compartments in the body

Question 1

what percentage of the body is solid matter, intracellular fluid, extracellular fluid?

Answer 1

solid matter ~40% (tissue/bone)
intracellular fluid ~40%
extracellular fluid ~ 20% (plasma, lymph, synovial fluid, GI tract fluid, cerebrospinal fluid)

Question 2

intracellular fluid description

what vol?

Answer 2

• fluid within cells
• 67% of total body water
• 28l in a 70kg person

Question 3

extracellular fluid description
what vol?
what does it consist of?

Answer 3

• fluids outside cells
• 14l in a 70kg person

consists of PLASMA (3L), INTERSTITIAL FLUID (10.2L), TRANSCELLULAR FLUID (0.8L)

Question 4

what keeps the balance between intracellular fluid and extracellular fluid?

Answer 4

kidneys- keep balance for tissue function

Question 5

what % and volume of the body weight is water?

what fraction of this is ICF and ECF? what vol?

Answer 5

• 60% O 42L in 70kg adult man
• 2/3 is ICF (28L)
• 1/3 is ECF (14L)

Question 6

of ECF what vol is transcellular fluid, plasma and interstitial fluid?

Answer 6

transcellular fluid - 0.8L
plasma - 3L
interstitial- 10.2L

Question 7

comparing ICF and ECF what is the difference in Na+ conc?

Answer 7

Na+ sig higher in ECF compared to ICF

Question 8

comparing ICF and ECF what is the difference in K+conc?

Answer 8

K+ sig higher in ICF compared to ECF

Question 9

comparing ICF and ECF what is the difference in Ca2+ conc?

Answer 9

Ca2+ higher in ECF compared to ICF

Question 10

comparing ICF and ECF what is the difference in pH?

Answer 10

pH = 7.0 in ICF 
pH = 7.4 in ECF

Question 11

comparing ICF and ECF what is the difference in osmolality?

Answer 11

290 mOsmoles/kg H2O in ICF
290mOsmoles/kg H2O in ECF

O no NET movement of water between these compartments- EQUIVALENT OSMOLALITY

Question 12

define osmolalilty

Answer 12

concentration of osmotically active molecules in a given compartment

Question 13

what are crystalloids?

Answer 13

when solutions contain small molecules- mainly salts that dissociate

Question 14

what are colloids?

Answer 14

solutions that contain larger molecules like proteins and polysaccharides

Question 15

what is osmotic pressure?

Answer 15

difference in conc of the impermeable solute exerts OSMOTIC PRESSURE

Question 16

give an example of where Na+ is freely permeable and what is its consequence
where is the net movement?

Answer 16

in the capillary wall O Na+ is not osmotically active here

BUT the cap.wall is IMPERMEABLE to PLASMA PROTEINS O extravascular proteins accumulate and exert osmotic effect and O water leaves

Question 17

water leaving the capillary and into interstitial fluid causes what?

Answer 17

causes SWELLING caused by protein accumulation in INFLAMMATION —- local oedema forms

Question 18

what is the name for alteration of osmotic forces caused by changes in conc of a large molecule (eg protein)

Answer 18

COLLOID osmotic pressures
or
ONCOTIC pressures

Question 19

what does HYPOTONIC solution cause?

Answer 19

causes cellular swelling

Question 20

what does HYPERTONIC solution cause?

Answer 20

causes cellular shrinkage

Question 21

give an example of an isotonic sol?

Answer 21

0.9% NaCl (saline sol)