system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can a heart operate for such a long time without faltering.

It just amazes me how we can have a pumping muscle that barely fails in the space of 50-70 years. I am a missing something obvious to how it can operate for so long?
gpt
Frankly, because it's designed that way. Heart muscle contains more mitochondria than skeletal muscle (arms, legs, etc) which generate energy for the muscle. The heart also gets first go at the fresh supply of oxygen coming from your lungs, so it's literally swimming in oxygen and energy - essentially, the rest of your muscles get the heart's leftovers.

The heart can still falter, however. Long-distance, endurance-type cardio exercise can cause damage to the heart, since it will continue to pump blood, rather than succumbing to muscle failure as skeletal muscles would due to lack of oxygen/energy.

It's also not a good idea to think of the heart like an engine. Engine (and heart) parts wear out over time, but engine parts aren't replaced until they fail. Heart parts (cells) can slowly die and be replaced by new ones, so hearts don't seize up like an engine would.