Death, a topic shrouded in mystery and often met with fear. Is it a process, a gradual fading, or an event, a sudden extinguishing? Let's delve into this profound question, exploring perspectives from science, philosophy, and spirituality.
In nearly all circumstances human death is a process rather than an event.
Unless caught up in nuclear explosions people do not die suddenly, like the bursting of a bubble.
- Classical death provides perhaps the best illustration of death as a process. Several minutes after the heart has stopped beating, a mini-electrocardiogram may be recorded, if one probes for signals from within the cardiac cavity. Three hours later, the pupils still respond to pilocarpine drops by contracting, and muscles repeatedly tapped may still mechanically shorten.
Clinical death
At the opposite end of the spectrum from cell death lies the death of a human being.
- Although death is defined at least in outline, the decision that a person is “dead” cannot be verified by any amount of scientific investigation
- The anatomical basis for such a concept of human death resides in the loss of brain-stem function
- If one seeks to marry conceptions of death prevalent in the oldest cultures with the most up-to-date observations from intensive care units, one might think of death as the irreversible loss of the capacity for consciousness combined with the irreversible, and therefore, the inability to breathe.
Functions of the Brain stem
The brain stem is the area at the base of the brain that includes the mesencephalon (midbrain), the pons, and the medulla.
- It contains the respiratory and vasomotor centres, which are responsible for breathing and the maintenance of blood pressure, and it also contains the ascending reticular activating system, which plays a crucial role in maintaining alertness and consciousness.
- Small, strategically situated lesions in the medial tegmental portions of the midbrain and rostral pons cause permanent coma.
The “Point of No Return”
At the clinical level, the irreversible cessation of circulation has for centuries been considered a point of no return.
- Circulatory arrest is a mechanism of death and not in itself a philosophical concept of death; that cessation of the heartbeat is only lethal if it lasts long enough to cause critical centres in the brain stem to die;
- These are not so much new facts as new ways of looking at old ones.
- The thracians kept their dead for three days before burial. The Romans kept the corpse considerably longer. The 16th-century Flemish physician Andreas Vesalius, probably the greatest anatomist of all time, professor of surgery in Padua for three years and later physician to the Holy Roman emperor Charles V, had to leave Spain in a hurry when the subject, a nobleman he had been attending, showed signs of life.
Cell death
Coagulative necrosis is the classical form of cell change seen when tissues autolyze (digest themselves) in vitro.
- But cells may die by design as well as by accident. The changes, which affect aggregates of adjacent cells or functionally related cohorts of cells, are seen in a variety of contexts produced by accident, injury, or disease.
- Necrosis is characterized by early swelling of the cytoplasm and of the mitochondria (energy-releasing organelles) within it.
