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Flashcards in Body Fluids Deck (109)
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1

Ions make up ...% of solutes

95%

2

Formula to calculate osmotic pressure

P = r × C × R × T

P: Osmotic pressure

r: reflection coefficient

C: Conc. of dissolved substance

R: General gas constant

T: Temperature

3

Describe the Reflection coefficient

  • If a substance cannot diffuse accross the membrane
    • Coefficient value = 1
  • If a substance can pass freely
    • Coefficient value = 0

4

Describe Molarity

​​mol/liter

  • Anelectrolites:
    • 1 mol dissolved substance in 1 litre
    • Has an osmotic pressure of 2.27 MPa

 

  • Molarity of body fluids:
    • Unit: mmol/l
    • Osmotic pressure measured in kPa

 

5

Osmolarity

1 osmol/l = 6×1023 dissolved substance / liter

6

Molality

mol/kg

  • No. mol of substance in 1kg solvent
  • Correlated with freezing point depression

7

Calculate molality

  • Electrolites:
    • Conc. x dissociation constant
    • (1 mol NaCl - 3.72°C)
  • Anelectrolites:
    • Conc. related to freezing point

8

Define Osmolality

Measures of the body's electrolyte-water balance

9

Freezing point depression for water

1.86 °C

10

Freezing point depression for blood plasma

0.56°C

11

Calculate osmolality: 

  • For dilute anelectrolite solutions

mosmol/kg = mmol/kg

12

Calculate osmolality:

  • For complete dissociation

moslmol/kg = mmol/kg x no. dissociated ions

(E.g NaCl has 2 dissociated ions, Na+ + Cl-)

13

Calculate osmolality:

  • For concentrated solutions
  • (Biological fluids)

mosmol/kg = mmol/kg x g

g: osmotic coefficient

Plasma NaCl - g=0.926

14

Oncotic/colloidosmotic pressure

Pressure maintained by proteins and colloid particles

15

Give the anelectrolite concentrations of the blood plasma

  • Glucose:
    • 5 mmol/l (Monogastric)
    • 3 mmol/l (Ruminants)
    • 10 mmol/l (Birds)
  • Urea: 3-10 mmol/l
  • NPN 15-25mmol/l

NPN = 'Non-protein nitrogen'

16

Give the concentrations of the cations in blood plasma

  • Na= 140 mmol/l
  • K= 4 mmol/l
  • Mg2+ = 1.5 mmol/l
  • Ca2+ = 1.25 mmol/l

17

Give the concentrations of the anions in blood plasma

  • Cl- = 110 mmol/l
  • HCO3- = 27 mmol/l
  • Protein = 17 mmol/l
  • Phosphate = 2 mmol/l
  • Sulphate = 1 mmol/l
  • Organic acids = 4 mmol/l

18

Value of osmolality of blood plasma calculated based on total electrolyte concentration

280 mmol/kg

19

Value of osmolality of blood plasma calculated by freezing point depression

300 mmol/kg

20

Calculate non-ionic osmolality

300 mmol/kg - 280 mmol/kg

(Freezing point osmolality - total electrolyte osmolality)

= 20 mmol/kg

21

Give the concentration of plasma proteins

60-80 g/l

22

Give the oncotic pressure (Osmotic pressure of plasma proteins)

2.7-3.4 kPa

23

Give the molarity of plasma proteins

1.2-1.5 mmol/l

24

How are plasma proteins quanitfied?

Kjeldahl method

25

  • Formula to calculate protein concentration
  • Approximate value

Oncotic pressure / Osmotic pressure of 1 mol/l

Approximately 2.5 mmol/l

26

100 µmol/l

27

50 (50-200) µmol/l

28

< 60-200 µmol/l

29

25%

30

50%