Biology 3.11 Oral Rehydration Therapy

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  • Created by: Anna
  • Created on: 20-04-13 21:59

What causes diarrhoea?

  • Damage to epithelial cells lining the intestine.
  • Loss of microvilli due to toxins.
  • Excessive secretion of water due to toxins e.g. cholera toxin.

Excessive fluid is lost and/or insufficient fluid taken in = dehydration, may be fatal.

What is oral rehydration therapy?

Drinking water is ineffective for rehydrating diarrhoea patient because:

  • Water not being absorbed in small intestine - sometimes e.g. cholera it is lost from the cells too.
  • Drinking water doesn't replace lost electrolytes (ions) being lost from epithelial cells.

More than one type of carrier protein in cell-surface membranes of epithelial cells that absorbs sodium ions.

As sodium ions are absorbed, water potential of cells falls and water enters by osmosis.

Rehydration solution therefore needs:

  • Water = rehydrates tissues.
  • Sodium = replaces lost sodium ions, makes optimum use of sodium-glucose carrier proteins.
  • Glucose = stimulates uptake of sodium ions, provides energy.
  • Potassium =…


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