While understanding mind we can say that consciousness is immortal. Each of the 50 to 70 trillion cells of the human body has 3 billion genetic codes. Each set has a complete genetic bridge. Carbon copies of each DNA is a copy of another. Brain neurons and skin cell are genetically similar. Despite being made from DNA, their work and life expectancy are different. Their functions are different and life span too.
The same DNA has created all kinds of cells, such as bone, liver, kidney, and every cell in a sophisticated way. However, every cell has a fixed life span. You can’t determine the lifetime of an organ looking only at the cell. For example, the neurons and cells of the nose are similar by seeing. But neuron cells exist for a number of years and general cells have changed in 4 weeks.
98% atom of the cell are changeable every year