It is a combination of a special type of muscle (cardiac muscle) nervous tissue which acts as the pace maker, valves that mean blood flows in the right direction, a tough membrane to contain the blood and help keep the heart in shape and blood vessels to supply it with oxygen and nutrients
Its made of very strong muscle which means that it can keep beating/pumping for our entire lifetime. Supporting this, the heart is covered in blood vessels that provide it with blood and then allow blood to flow to and from. The valves inside the heart are really cool as they allow blood to pass one way but then slam shut to keep the blood moving one direction.
Not much for me to add….but a little fact about obesity…..the amount of fat around the heart in obese individuals is a great predictor for the risk of having atrial fibrillation…..the most common heart aryrtmia!!!!