Physiology and pathophysiology of senescence

Average life-span and maximum life-span are the two basic parameters by which the processes of ageing and senescence of individuals of a species are characterized. Although each individual of a species if affected by both parameters can only be studied in populations of individuals. The survival curve of a cohort of individuals reflects the different influences of constitutional and environmental factors on life expectancy. The intrinsic molecular and cellular mechanisms by which the physiological process of ageing and senescence is controlled and regulated are far from being understood although a large number of hypotheses have emerged over the decades. Stochastic and deterministic models of the ageing process have been developed but a theory unifying the large body of experimental, epidemiological and clinical findings is still lacking. In this contribution a brief review is presented on the different hypotheses aiming at explaining the physiology and pathophysiology of ageing and senescence.