Fluid can be lost when you have picked up an infection and you could have developed symptoms of vomiting or diarrhoea the water will then be lost from the digestive tract in the form of vomit or faeces. When the fluid turns into an isotonic fluid such as sodium chloride the depletion will have entirely occurred from the extracellular fluid. If the hypertonic fluid is deposited in an extracellular fluid compartment the gap of missing water in the intracellular fluid will be found in the extracellular fluid compartment and the compartment will increase in size due to the extra water.
When water is lost from the intra/extracellular fluid compartment certain responses will occur such as vasopressin secretion, stimulation of the renin-angiotensin-aldosterone