Death

It is the permanent breakdown or stopping of the vital functions of the body like heart beat, breathing, etc.

As natural process it occurs in higher animals. It is “the price paid for achieving higher grade of organisation.

Characteristics of death

It is the end result of degenerative process of ageing ; widespread cell death occurs mainly due to anoxia of the tissues.

A cells do not die at the same time, e.g. Cells of respiratory tract continue to beat their cilia hairs grow out. Cornea remains viable, muscles remain alive for some time even after death. Sperm cells can be isolated alive from the testis of a dead person after some hours of death.

Causes of death

Unabated irreversible damage to body tissues and vital organs like heart, lungs, liver, kidney etc. Due to stoppage of blood supply (ischemia) to brain and heart. Massive infection due to loss of immunity. Morphological patterns of cell death

There are two morphological patterns of death :

• Necrosis
• Apoptosis.

Necrosis :

Accidental or pathological cell death if cell is exposed to extreme physiological variation, like hypoxia, hyperthermia which damage the cell membrane. It begins with impairment of the cells ability to maintain homeostasis. Intra-cellular organelles, mainly mitochondria, swell and rupture.

Apoptosis :

It is a kind of programmed cell death, under normal physiological conditions (homeostasis) cell itself is actively involved in its own death (cell suicide).

It occurs during embryogenesis related to nervous and endocrine dependent atrophy. There is no disintegration of organelles, which rather remain intact.