Final answer:
It is false that extracellular fluid depletion is the last line of defense against dehydration. Dehydration impacts both extracellular and intracellular fluid compartments, showing symptoms after about 2% of total body water is lost, and has serious health implications if not addressed.
Step-by-step explanation:
The statement that extracellular fluid depletion is the last line of defense against dehydration is false. In fact, extracellular fluid is one of the first areas affected by dehydration. When excessive water loss occurs due to factors such as vomiting, prolonged diarrhoea, or sweating, the concentration of the extracellular fluid increases, causing water to be drawn out from the cells, leading to a decrease in both intracellular and extracellular fluid volumes. This process results in symptoms like extreme thirst, a hot and dry body, and a dry tongue.
Dehydration occurs when there is a negative water balance in the body, meaning that more water is lost than is taken in. Symptoms of dehydration include lightheadedness, dizziness, and fainting, which are noticeable after about 2% of total body water is lost. It's important to understand that dehydration affects not just the extracellular compartment but the intracellular compartment as well. Maintaining proper hydration is essential for our body's function. Thirst is a mechanism triggered by various factors, including dry mouth, low blood volume, or high blood electrolyte concentrations, to stimulate the feeling of needing to drink. Proper balance between water intake and loss is crucial for optimal functioning of the body's systems.