What is the primary effect of alkali exposure on body tissues?

The primary effect of alkali exposure on body tissues is liquefactive necrosis. This occurs because alkalis, which are strong bases, have the ability to dissolve cell membranes and proteins, leading to the breakdown of cellular structures. The high pH of alkalis causes saponification of fats, which results in fluid accumulation and the transformation of solid tissue into a viscous, liquid state. This process is particularly pronounced in tissues with high lipid content, such as the brain.

In contrast, other processes such as coagulation of proteins are more typically associated with the effects of acids rather than alkalis. The die-off of nerve fibers, while it might occur in certain conditions, is not the primary effect of alkali exposure. The formation of thrombi does not directly relate to the mechanism of alkali action on tissues, as this is more associated with vascular injury and clotting processes, rather than the cellular necrosis caused by alkali exposure. Thus, liquefactive necrosis stands out as the correct primary effect of alkali on tissues.