Studied by 0 people
Looks like no one added any tags here yet for you.
Body fluid compartments.
Intracellular fluid, extracellular fluid, interstitial fluid, plasma, and transcellular fluid.
Describe the distribution of water of the body fluid compartments.
ICF 28 litres in a 70 kg person, ECF 14 litres, interstitial fluid 10.2 litres, plasma 3 litres and transcellular fluid 0.8 litres.
Describe the distribution of ionic composition of the body fluid compartments.
In interstitial fluid there is high potassium and low sodium, whereas in extracellular fluid there is low potassium and high sodium.
Concept of osmosis.
The movement of water molecules from a low solute concentration to a high solute concentration.
Osmotic pressure
Is the pressure that must be applied to oppose osmosis.
Osmolarity.
The total number of dissolved particles per litre of a solution.
Molarity x number of particles per molecule (once the particle dissolves).
Osmolality.
The total number of dissolved particles per Kg of water.
Oncotic pressure/ colloid osmotic
An alteration of osmotic forces due to changes of a large molecule distribution.
Explain the cause of movement of water particles across cell membrane and the capillary bed during osmosis.
Influenced by membrane properties and osmotically active solutes e.g. Na+ and Cl- . Cell membrane is nearly impermeable to Na+. If ECF [Na+] increases cell shrinks. In capillary bed water movement depends on hydrostatic pressure and osmotic pressure. Na+/ K+ pump helps maintain osmotic balance by actively transporting Na+ out.
Principles of tonicity.
Isotonic solution: have the same osmolality as plasma = 290 mosmoles/kg H2O
Hypertonic solutions: have a greater osmolality than plasma = >290 mosmoles/kg H2O
Hypotonic solutions: have a lower osmolality than plasma = <290 mosmoles/kg H2O
Intracellular fluid ICF
Fluid within cells also known as cytoplasm.
Extracellular fluid ECF
All fluids outside the cells.
Interstitial fluid
Fluid between cells of tissues, including lymph.
Plasma
Fluid in the vascular space.
Transcellular fluid
Fluid in the cerebrospinal fluid, joints, G-I tract.
