Chem path fluid balance

Question 1

Where is body fluid?

Answer 1

60 percent of total body weight is water
40 percent of this is intracellular
20 percent of this is extracellular

60 to 40 to 20 rule

Question 2

How many litres of water is intracellular?

Answer 2

28 L

Question 3

Name three extracellular spaces and their volume contents

Answer 3

In total = 14 L

Interstitial (between cells) = 10 L
Intravascular = 3 L
Transcellular (within epithelial enclosures e.g. CSF, bladder) = 1 L

Question 4

Difference between osmolarity and osmolality

Answer 4

Osmolarity = concentration of particles in 1 L, mmol/L
Osmolality = concentration of all particles in 1Kg, measured in mmol/kg

Question 5

What do you call the difference between osmolality and osmolarity?

Answer 5

Osmolar gap

Question 6

What is the equation for determining osmolarity?

Answer 6

2 x (Na and K) + urea and glucose

Question 7

What is the normal range for serum osmolality?

Answer 7

275-295mmol/Kg