The tissues most often damaged as a result of inorganic mercury entering the body include all of the following except:

Inorganic mercury is known to cause harm primarily to the kidneys and the brain due to its toxic effects on critical cellular structures and functions. The kidneys are particularly vulnerable because they are responsible for filtering blood and excreting waste. Mercury can accumulate in renal tissues and lead to nephrotoxicity, resulting in dysfunction or failure.

The brain is another critical target for inorganic mercury, with the metal's neurotoxic effects potentially leading to cognitive and neurological impairments. This can manifest in various ways, including mood changes, memory issues, and motor function problems.

While the liver does play a role in metabolizing various substances, it is generally less affected by inorganic mercury compared to the kidneys and brain. Kidney damage is a classic effect, and neurological impacts are well-documented, highlighting the brain's susceptibility to mercury exposure.

The heart, while it can be affected by various toxins, is not the primary organ of concern regarding inorganic mercury. Therefore, within the context of inorganic mercury toxicity, the heart is less likely to experience significant direct damage compared to the kidney and brain, making it the correct choice as the exception in the question.