The Scientific Explanation Of Death

Death is culturally and socially commonly deemed as an extremely unfortunate circumstance. It could leave persons with familial or cordial relationships with the deceased in chronic psychological stress, deep emotional trauma, extreme grief, sorrow, and depressing conditions. It is what we live to avoid every day. In this article, we shall see what death means clinically and how biological factors determine and set the boundaries between life and death.

The biomedical definition of death

Death could be portrayed as a state in which all physiological processes which sustain life are terminated irreversibly. The process of death is undoubtedly a complex one. Because not all cells die at the same time, there is difficulty in establishing a death case. This is furthermore complicated as it is somewhat possible to restore a person who has been affirmed clinically dead.

General clinical features which confirm that an animal is dead include:

1. Cardiac activity is non-existent and heart pulse completely vanishes.

3. Permanent unconsciousness: the person remains in a quiescent state and is persistently unresponsive to any kind of stimuli. There is no record of electrical activity in the brainstem which regulates reflexes such as blood pressure and breathing and in the cortex which coordinates higher-level cognitive functions.

3. Mechanical Ventilation and respiration cease. Pulmonary and systemic circulation stops.

ECG (Electrocardiogram) grids are very useful in detecting cardiac activity and complications. Courtesy: pexel

Brain Death or Cardiac Death?

Death could be ascertained when neuronal activity is permanently lost in the brain. The person must remain irrevocably unconscious.  This notion is considered valid because the brain is the central coordinator of other internal organs and psychological qualities which characterize a living person. Hence most clinical personnel proclaim a person to be dead after an EEG measurement determination. (The brain wave appears flat).

Cardiac Death due to a cardiac arrest could be argued as a primary indicator of death. This idea posits that death ensues immediately after the heart ceases to function and blood flow ends. This is usually accompanied by unconsciousness and respiratory failure. In this state, the person could be considered to be dead as he or she can no longer perform very critical biological processes such as blood circulation, oxygen delivery, respiration and metabolism. Today in medical practice, cardiac death is not a basis for confirmation because CPR (cardiopulmonary resuscitation) if properly performed can be used to revive a 'dead' heart.

Clinically important pointouts concerning the death

1. Lack of proper drainage of blood from the brain particularly in cases of severe brain injury causes haemorrhage. Any trauma leading to disruption of blood flow (lacerations of blood vessels, death of brain tissue, e.t.c) to the brain automatically results in brain death.

2. Cardiac muscle can be revived by employing CPR if an electrical current is passed to reactivate the SA node.

3. Brain damage becomes progressively inevitable if the blood supply to this brain is disrupted for about five minutes or longer. Even if cardiac arrest is successfully treated, the person may continue to suffer from the effects of neurological death already sustained. This appears to be irreversible.

4. All metabolic processes such as glucose assimilation and energy production is permanently halted. Life is no longer sustained and tissues begin to die and gradually deteriorate.

Phases of death

1. Paleness: the first feature of a dead person is pale looking skin. The person appears lighter than usual superficially. Blood vessels within the body and around the skin begin to deteriorate and disintegrate. Blood is not conducted to the skin making it look white. Also note that because blood is not delivered to tissues, hypoxia and necrosis results.

2. Hypothermia: the cessation of metabolism causes a decline in body temperature. This is useful forensically as calculations of the rate of temperature decrease can be used to estimate the time of death (or how long the person has been dead).

3. Stiffness: this can indicate that the person is dead. Also known as Rigor mortis, this condition is due to the leakage of calcium ions through the membranes and sarcoplasmic reticulum. Calcium binds to troponin and leads to contractions of skeletal muscle but does not relax without ATP. Adenosine triphosphate is required from myosin to come to be detached from actin. Since the metabolism is halted, the muscle remains contracted. Intracellular proteins such as cathepsins decompose the molecular complexes. These are further decomposed microbially.

4. Gravitational pull makes fluid such as blood accumulate at the distal areas

5. After a substantial period, putrefaction occurs. Bacteria commences decomposing the cadaver leading to bloating and release of noxious amines like putrescine and cadaverine. Various types of flies can be observed feeding on the carcass depending on the duration of death.

6. Skeletonization begins after extensive decomposition of the corpse. Decay products such as "liquid" are produced and all muscles, organs and even the marrow of bones are expected to have decomposed. The skeleton of the animals is now noticeable by this time.

Gradual decomposition and skeletonization of a jackal carcass. Geological processes over time can lead to the fossilization of dead animals. Courtesy: istock.

Biological Miracle: Lazarus sign and Lazarus phenomenon

These two events are called after the biblical Lazarus who was allegedly resurrected by Jesus Christ according to the Gospel of John

Lazarus sign is a condition in which a brain-dead patient (cortex and brainstem) exhibits some reflex movements such as flexing and elevation of the limb. This could appear as a miracle to those who witness it.

Analysis of the Lazarus sign

The brain is not responsible for simple reflex actions. This is performed by the spinal cord. The reflex arc does not involve the brain. So even if the brain tissues are destroyed, the spinal cord could still function which can consequently result in the observed limb movements.

Some people "come back to life" after several CPR procedures have failed. This is known as the Lazarus phenomenon. This rare event occurs spontaneously, restoring the person's normal heart functions after all resuscitation trials have been performed but to no avail.

Guinness world record holder

The person who holds the record for the longest time spent between clinical declaration of death and restoration of life is Velma Thomas (2008) who suffered from a cardiac arrest. According to online sources, after several CPR procedures failed, she was thereafter declared dead. She however woke up 10 minutes later after the declaration having spent 17 hours without cardiac activity. Miraculous isn't it?

Does it truly inevitable for all species. We can say it is truly the final fate of life.

Really?

Some animals are considered to be immortal. How true is this? How do they live forever? Find out in my upcoming episode, "immortality".