The body is constantly undergoing changes right from the birth till death. These changes are termed as ageing or Senescence. It is a biological process of age related deterioration in function. All these changes lead to the death of human being. The studies of human ageing have come out with conflicting theories, evoked controversies and puzzling data. Ageing is the change that occurs in cells, tissues and organs.
Various chemical modifications like oxidation, glycation and cross-linking weaken the molecular functioning of multiple vital components. Those vital components include the extracellular matrix, enzymes, DNA membrane and structural proteins. Some of these components get accumulated faster than they are repaired or recycled and lead to deterioration.
Due to some these modifications the redox potential poise of certain cells changes which results in altered gene expression, altered enzyme activity and altered signaling pathways. Further, even the repair and recycling mechanism slows down. The neuro-endocrine and immune system show the signs of decline and sends chemical signals of differentiation and death to different tissues.
The individual starts losing the non-dividing cells of the heart, brain substantia nigra and skeletal muscles due to necrosis and apoptosis. When cells are lost faster than they are replaced this is the time when the individual undergoes Senescence which is the deterioration process in humans.