3. Isotonic
What is Isotonic?
• Isotonic (‘iso’ means ‘the same’ and ‘tonic’
means ‘pressure’). When isotonic is used to
describe solutions for human consumption, it
means having the same fluid pressure as body
fluids.
• Tears, blood plasma, lymph and other body
fluids are all isotonic. Everything we eat and
drink must be made isotonic before passing to
the small intestine so the body can absorb it.
4. Hypertonic.
• If the solute concentration outside the cell is greater
than that inside the cell, the solution is hypertonic.
• Water will flow out of the cell, and crenation results.
5. Hypotonic
• If the solute concentration outside the cell is less
than that inside the cell, the solution is hypotonic.
• Water will flow into the cell, and hemolysis results.
6. Electrolyte Balance
• Cations – positively charged ions
• Anions – negatively charged ions
• Body fluids also contain charged organic
molecules
• Only a small percentage of molecules in fluids
are non-electrolytes: glucose, urea, creatinine
7. Functions of electrolytes
• Certain ions control the osmosis of water
between body compartments
• Ions help maintain the acid-base balance
necessary for cellular activity
• Ions carry electric current, which allows for
action potentials and secretion of
neurotransmitters
• Several ions are cofactors needed for the
optimal activity of enzymes
