Final answer:
When red blood cells are destroyed following an injection, it suggests the solution was hypotonic and not isotonic, as it caused water to enter and lyse the cells. Tonicity is crucial to maintain cell integrity; therefore, intravenous solutions must be isotonic to prevent damage to cells.
Step-by-step explanation:
The question at hand delves into the concept of tonicity and its relevance to the health of cells when solutions with varying osmolarities are introduced into the body. If red blood cells are destroyed as a result of a subcutaneous injection, as described in the given scenarios, it suggests that the solution administered was not indeed isotonic.
An isotonic solution would have the same osmolarity as the cells, thus not causing water to move across the cellular membrane, avoiding any change in the cell's volume. Since the cells burst, this points to the solution actually being hypotonic, as a hypotonic solution has a lower osmolarity compared to the cells, causing water to enter the cells and leading to their lysis.
It is important for solutions administered intravenously, like normal saline and lactated Ringer's solution, to be isotonic to prevent the cells from shrinking (in a hypertonic solution) or swelling and bursting (in a hypotonic solution). The tonicity of a solution is crucial in maintaining the integrity of the cells, directly impacting a patient's health. Thus, if red blood cells have been destroyed, it indicates that the solution was indeed hypotonic, not isotonic as the doctor presumed.