Misunderstanding may arise by confusing the Buddhist and scientific definitions of death. Within the scientific system you spoke quite validly of the death of the brain and the death of heart. Different parts of the body can die separately. However, in the Buddhist system, the word death is not used in that way. You'd never speak of the death of a particular part of the body, but rather of the death of an entire person. When people say that a certain person died, we don't ask, "Well, which part died?"
How does one stay mindful? Where feelings are known as they arise, known as they persist, known as they pass away. Thoughts are known as they arise, known as they persist, known as they pass away. Perceptions are known they arise, known as they persist, known as they pass away. This is how a monk stays awake.
Human beings by nature want happiness and do not want suffering. With that
feeling everyone tries to achieve happiness and tries to get rid of suffering, and everyone has the basic right to do this. In this way, all here are the same, whether rich or poor, educated or uneducated, Easterner or Westerner, believer or non-believer, and within believers whether Buddhist, Christian, Jewish, Muslim, and so on. Basically, from the viewpoint of real human value we are all the same.
I, ever knowing the living beings Who tread the Path and those who do not In response to those who may be saved Preach to them a variety of dharmas, Each time having this thought: 'How may I cause the beings To contrive to enter the Unexcelled Path and quickly to perfect the Buddha-body?'