بسم الله الرحمن الرحيم

1. بسم الله الرحمن الرحيم SHENDI UNIVERSITY FACULTY OF MEDICNE Body Fluids By:Mohammed Nour Lecturerin Human physiology

2. Composition &Measurement of Body Fluids Learning objectives: Identify the ionic composition of both ECF&ICF. Compare the ionic composition between plasma and ISF. Explain the mechanism that produced slight differences in ionic composition of plasma & ISF. Describe the principle of Dye dilution method. Mention the criteria for marker used to measured fluid volumes. Identify the markers are used to measure each compartment.

3. Ionic composition of ECF & ICF Electrolytes : are charged ions. Cations (positive): like (Na+ ,K+, Mg++ ,Ca++,……). Anions (negative): like ( CL-, HCO-3, PO4, protein,.......).

4. Importance of electrolytes

5. COMPOSITION OF BODY FLUIDS

6. Questions The compositions of ICF and ECF are not uniform why? The major difference between composition of plasma & ISF, plasma contain more protein than ISF why? What is the mechanism that produced slight differences in ionic compositions of plasma & ISF?

7. Gibs-Donnan effect Proteins have a net negative charge that tends to increase the cation concentrations and reduce the anion concentrations in the plasma compartment.

8. videoplayback_2.MP4

9. Measurement of body fluid Q (X) =500mg V=? Conce.(X)= 0.5mg/ml 500mg Q (X) = = V = 1000ml Conce.(X) o.5mg/ml Dilution Principle:

10. Criteria of measuring marker Not toxic Easy to measure Distributed only in the compartment being measured. Not easily secreted or metabolized. Not alter the volume of the compartment being measured.

11. Markers used for measurement TBV= Plasma volume X 100 100- HCt Plasma volume: Markers should stay in vascular system. Evan,s Blue Radioactive iodine serum albumin (RISA) These two markers are tightly bound to plasma protein. Calculation of blood volume:

12. Markers used for measurement ECF volume: Substance used for measure ECF distribute only in ECF. Substances are used to measure ECF volume: Saccharides: e.g. sucrose , inulin & mannitol. Diffusible ions: e.g. radio-sodium, radio-chloride, thiosulphate & radio-sulphate.

13. Markers used for measurement TOTAL BODY WATER (TBW) Markers used: Deuterium oxide (D2O). Tritiated water . Antipyrine Aminopyrine.

14. ISF & ICF volumes ISF = ECF – Plasma Volume ICF = TBW – ECF They are not measured directly. They are calculated.

15. Calculation Question An individual’s urinary bladder is catheterized and drained, then 2.4 g of inulin is injected intravenously; 6 hours later, a venous sample is withdrawn and found to have a plasma inulin concentration of 0.1 mg/mL. During this 6 hours, 200 mL of urine was produced having an inulin concentration of 5 mg/mL. what is the volume of ECF?

16. { وَقُل رَّبِّ زِدْنِي عِلْماً } طه 114

17. بسم الله الرحمن الرحيم SHENDI UNIVERSITY FACULTY OF MEDICNE Body Fluids By:Mohammed Nour Lecturerin Human physiology

18. Lecture 4

19. Units for Measuring Solute concentrations • amounts of solute are expressed in moles, equivalents, or osmoles. • Mole:is the gram-molecular weight of a substance. • Equivalent: is the number of moles of the solute multiplied by its valence • osmole: is the number of particles into which a solute dissociates in solution.

20. Units for Measuring Solute concentrations Electrolytes are express in small units. mmole/L = mEq/L for monovalentcations. mEg/L for divalent cations = mmole/L × valence. mOsmole/L = mmole/L for non dissociated particles. E.g. urea and glucose. mOsmole/L = N × mmole/L for dissociated particles. E.g. NaCl, CaCL2.

21. Fluids movement Water moves freely across cell membrane by osmosis.

22. Osmosis • Definition : Is the movement of water molecules across a semi-permeable membrane from a region of low concentration of solute to a region of high concentration of solute.

23. B A B A solute B A Osmosis

24. Osmolarity and Osmolality • Osmolarity:is the number of osmoles per liter of solution . • Osmolality:is the number of osmoles per kilogram of solvent. • Osmolality is importance in determining the distribution of water between ICF and ECF compartments. • Normal plasma osmolarity 280- 300mosm/l • The osmolarity of ECF= osmolarity of ICF.

25. Determination of osmolarity Plasma osmolarity is mainly determined by Na+. ICF osmolarity is mainly determined by K+. Estimation of plasma osmolarity: Plasma osmolarity = 2× plasma Na+. Glucose and urea contribute significantly when hyperglycemia or uremia is present. Osmolarity = 2× plasma Na+ + Glucose + BUN 18 2.8

26. Osmolality Osmolality of ECF =osmolality of ICF ICF and ECF are in osmotic equilibrium. If the osmolality changes in one compartment, water moves so as to restore a new osmotic equilibrium.

27. Relation between osmolality & osmotic pressure • Osmotic pressure is the pressure necessary to prevent osmosis. • The osmotic pressure of a solution at body temperature of 37co can be determined approximately from the following formula :- • osmotic pressure= 19.3 mmHg x osmolality. • Where 19.3mmHg is osmotic pressure create by one osmole. The osmotic pressure in the plasma(280mOsm/l) is about 5404mmHg.

28. Calculation of molarity & osmolarity Molarity = Amount of solute (in grams) per liter M = ---------------------------------------------- Mol. Wt. of solute Osmolarity = number of mmol x number of osmoles.

29. Calculation Calculate the molarity & osmolarity of: 0.9% NaCl? (MWt= 58.5) 5% glucose?(MWt= 180)

30. Self-study questions

31. { وَقُل رَّبِّ زِدْنِي عِلْماً } طه 114