HUBS ECF

135-145 mmol/L

2-2.5 mmol/L

• Fasting 3.5-6 mmol/L
• Non fasting 3.5-8 mmol/L

3.5-5 mmol/L

7.35-7.45

About 37C (36-38C)

• Main extracellular cation
• Determines ECF volume and therefore influences blood pressure
• Action potential generation - nerve/muscle

• Structural component - bone and teeth
• Neurotransmission and muscle contraction
• Coagulation
• Regulates enzyme function

Used by cells - produce adenosine triphosphate (ATP)

• Most abundant ICF cation
• Determinant resting membrane potential

• Chemical reactions slow down preventing cell function
• Complete loss of temperature regulation

• Denaturing of enzymes
• Temperature regulation impairment

• Simple diffusion
• Simple diffusion via membrane channels
• Carrier mediated passive transport

275-300 mosmol/L

Measure of total number solute particles per litre of solution in osmol/L

• Effect a specific solution has on cell volume.
• Influenced by type of solution - specifically whether solute particles can cross cell membrane 

No change in cell volume

Increase in cell volume - cells will swell

Loss of cell volume - cells will shrink

The maintenance of relatively constant conditions in the internal environment if the face of external or internal change. 

• An active cell membrane transport system that moves 3 sodium ions out of the cell in exchange of 2 potassium ions.
• Maintains ionic gradients and helps regulate cell volume.

Amount of solute particles per kg of water in osmol/kg.

Higher solute concentration than cell

Lower solute concentration than cell

Same solute concentration as cell

• Male - 60%
• Female - 55%

1/3

2/3

1/5

4/5