Body Fluid Compartments

Question 1

What are the units of osmolarity?

Answer 1

osmol/l

Question 2

What is required to calculate osmolarity?

Answer 2

2 factors i.e. 150mM NaCl and 100mM MgCl2

Question 3

What is tonicity?

Answer 3

the effect on cell volume
isotonic - normal
hypotonic - too much water
hypertonic - too little water

Question 4

What does hypertonicity cause?

Answer 4

cell shrinkage

Question 5

What does hypotonicity cause?

Answer 5

cell lysis from swelling

Question 6

What are the units of osmolality?

Answer 6

osmol/kg

Question 7

What is different between osmolarity and tonicity?

Answer 7

tonicity takes into consideration the ability of a solute to cross the cell membrane

Question 8

What is the Total Body Water percentage of a male and female?

Answer 8

male 60% of body weight

female 50% of body weight

Question 9

What does total body water exist as?

Answer 9

2 major compartments of ICF and ECF

Question 10

What is the concentration of water in ICF and ECF?

Answer 10

ICF 67% TBW

ECF 33% of TBW

Question 11

What is included in EC fluid?

Answer 11

plasma
interstitial fluid
lymph - negligible
transcellular fluid - negligible

Question 12

How might you trace TBW?

Answer 12

3H2O

Question 13

How might you trace ECF?

Answer 13

Inulin

Question 14

How might you trace plasma?

Answer 14

labelled albumin

Question 15

What is TBW equivalent to?

Answer 15

ECF+ICF

Question 16

How do you measure the volume of distribution?

Answer 16

take the tracer and equilibrate it with water
take a small sample and measure the concentration
c=m/v
work out volume of distribution

Question 17

What is the equation for calculating the volume of distribution?

Answer 17

V (L)=Dose/Sample concentration

Question 18

What is insensible loss of water?

Answer 18

loss through skin and lungs

Question 19

What is sensible loss of water?

Answer 19

faeces
urine
sweat

Question 20

What is the general input and output of water/day?

Answer 20

2500ml

Question 21

What may increase water loss through sweat?

Answer 21

hot weather and exercise

Question 22

What may increase water loss through the lungs?

Answer 22

exercise

Question 23

What decreases the water loss from urine?

Answer 23

hot weather and exercise

Question 24

What is the general ICF and ECF concentrations of Na?

Answer 24

ICF - 10

ECF -140

Question 25

What is the general ICF and ECF concentrations of K?

Answer 25

ICF - 140 | ECF - 4.5

Question 26

What is the general ICF and ECF concentrations of Cl?

Answer 26

ICF - 7 | ECF - 115

Question 27

What is the general ICF and ECF concentrations of HCO3?

Answer 27

ICF -10 | ECF -28

Question 28

What is particularly potent in the plasma?

Answer 28

Na, Cl, HCO3, protein anions

Question 29

What is particularly potent in the interstitial fluid?

Answer 29

Na, HCO3, Cl

Question 30

What is particularly potent in the IC fluid?

Answer 30

K, PO4, Mg, protein anions, small Na

Question 31

What is the difference in osmotic concentration of ECF and ICF?

Answer 31

none - they are identical

Question 32

Why is there no difference in ICF and ECF?

Answer 32

because any change in solute concentration leads to immediate change in water distribution

Question 33

What is fluid shift?

Answer 33

the movement of water between the ICF and ECF in response to an osmotic gradient

Question 34

What are some challenges to fluid homeostasis?

Answer 34

gain or loss of water gain or loss of NaCl gain or loss of isotonic fluid

Question 35

What happens when NaCl is gained in the ECF?

Answer 35

ECF increases water volume | ICF decreases water volume

Question 36

What happens when NaCl is lost in the ECF?

Answer 36

ECF loses water volume | ICF gains water volume

Question 37

what does a gain or loss of isotonic fluid cause?

Answer 37

change in ECF volume but not fluid osmolarity

Question 38

What alters the composition and volume of the ECF?

Answer 38

kidney

Question 39

What is regulation of ECF vital for?

Answer 39

regulation of blood pressure

Question 40

What is electrolyte balance important for?

Answer 40

can directly affect water balance | the concentrations of electrolytes can affect cell function

Question 41

What is particularly important about Na and K?

Answer 41

they are major contributors to the osmotic concentrations of ECF and ICF they directly affect the functioning of all cells

Question 42

What can result from increasing plasma K?

Answer 42

muscle weakness - paralysis | cardiac irregularities - cardiac arrest