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بسم الله الرحمن الرحيم. SHENDI UNIVERSITY FACULTY OF MEDICNE. Body Fluids By: Mohammed Nour Lecturer in Human physiology. Tonicity & I.V solutions. Objectives : Define tonicity? Explain the difference between tonicity & osmolalty ?
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بسم الله الرحمن الرحيم SHENDI UNIVERSITY FACULTY OF MEDICNE Body Fluids By:Mohammed Nour Lecturerin Human physiology
Tonicity & I.V solutions • Objectives : • Define tonicity? • Explain the difference between tonicity & osmolalty? • Identify the types of I.V solution & their clinical indications. • Describe the effects of each type on ECF and ICF volumes & osmolarities. • Calculation of new volumes & new osmoles.
Tonicity • Is term used to describe the effect of solution on the volume of the cell.
Type of I.V solutions 1.Isotonic solution : (osmolality similar to plasma) e.g. Nacl 0.9% ( normal saline) or glucose 5% 2. Hypotonic solution : (osmolality lower than plasma) e.g.Nacl less than 0.9% or glucose less than 5%. 3. Hypertonic solution : (osmolality higher than plasma) e.g. glucose 5% with normal saline 0.9%.
Clinical indications of I.V solutions • Prevention and treatment of dehydration. • Water and salt depletion – diarrhoea. • Hypovolemic shock. • Plasma volume expansion.
Effects of different types of solution on red blood cells volume A. isotonic C.hypertonic B. hypotonic
Effects of different types of solution on red blood cells volume
Effects of I.V. infusion of type of solutions on volumes & osmolalities of ECF &ICF.
Example: • Assume the standard 70 kg male, in whom the original osmolality of the ECF is 290 mOsm/kg water. Consider addition of 2 liters of distilled water to the ECF. Calculate the effect of this addition on the volumes and osmolality of the ECF and ICF .
A 50-kg individual with a plasma [Na+] of 145 mEq/L is infused with 5 g/kg of mannitol (molecular weight of mannitol = 182 g/mol) to reduce brain swelling after a stroke. After equilibration, estimate the following:
New equilibrium conditions (after mannitol infusion): • Total body osmoles: ____________ mOsm • ICF osmoles: ____________ mOsm • ECF osmoles: ____________ mOsm • Plasma osmolality: ____________ mOsm/kg H2O • Plasma [Na+]: ____________ mEq/L