Colligative Properties and Osmolality - need to finish

Osmometry

Technique for measuring the concentration of solute particles that contribute to the osmotic pressure of a solution

Osmotic Pressure

Controls the movement of solutes and water across semi-permeable membranes in the body

-Large molecules (proteins) cannot cross membrane

-Small molecules (ions) regulate osmotic equilibrium

Osmoles

Moles of solute that contribute to the osmotic pressure of a solution

-used for osmotically active solutions (like plasma)

Osmolality

Concentration of a solution expressed as the total number of osmoles per kilogram

-NOT affected by solute nature (size, charge)

-Determines body's state of hydration

-high solute —> dehydrated; plasma is more concentrated

Colligative Properties

Physical properties of a solution

-dissolved solutes change the physical properties of a solution

-Colligative = bound together; depends on the number of solute particles and not the type of chemical species

Osmolarity

The number of particles of solute per liter of solutions

Specimen for Osmolality

-Usually need serum/plasma results

-Random urine

-timed urine- more reliable

Colligative Properties Definition

-Freezing Point Depression

-Boiling Point Elevation

-Vapor Pressure lowering

-Osmotic pressure