Which condition involves capillaries becoming overly permeable, leading to a loss of blood volume?

The condition involving capillaries becoming overly permeable, leading to a loss of blood volume, aligns closely with the concept of excessive permeability. When capillaries increase their permeability, they allow larger molecules and even cells to pass through their walls more easily. This can result in fluids leaking into surrounding tissues, which can significantly decrease the effective blood volume within the vascular system, potentially leading to issues such as shock or fluid imbalances in the body.

In contrast, hypertension refers to high blood pressure, which does not inherently involve changes in capillary permeability. Heart attack and myocardial infarction refer to the same cardiac event where blood flow to a part of the heart is blocked, but these conditions fundamentally relate to issues in the coronary vessels and heart function rather than the permeability of capillaries.