The physiology of ageing

Britain's ageing population is growing at its fastest rate to date, making it increasingly important for clinicians to understand the physiological changes associated with ageing and recognize the difference between changes secondary to ageing and changes that occur as a result of disease. Ageing is characterized by a progressive and heterogeneous decline in physiological reserve of all organ systems, albeit at different rates, which vary in different individuals. Cellular senescence, although beneficial early in life, is likely to contribute. An age-related decline in reserve and compromise of homeostasis have important clinical implications for the interpretation of physiological findings and for understanding the atypical presentations of illnesses in older patients.