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eight - Towards understanding the biological drivers of cell ageing
- Edited by Alan Walker, The University of Sheffield
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- Book:
- The New Dynamics of Ageing Volume 2
- Published by:
- Bristol University Press
- Published online:
- 13 April 2022
- Print publication:
- 25 July 2018, pp 131-154
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Summary
Introduction
Ageing of the human body results in gradual loss of tissue and organ function, with consequent frailty and illness leading to poor quality of later life for many older people. Such ageing is thought to result from an accumulation of senescent cells that are unable to divide, leading to failure to replenish or repair the body – such non-dividing cells are said to be ‘senescent’. In this New Dynamics of Ageing (NDA)-funded project, we aimed to investigate what causes cell senescence at the very fundamental level of the genes involved and the proteins they encode.
The human body is composed of trillions of cells, some of which are as old as the individual and some of which are renewed on an almost daily basis (Spalding et al, 2005). Cells of the same type are organised into tissues, and then organs are made up of different types of tissues comprising a range of cells with highly specialised functions. Organs such as the heart cooperate with other tissue and organs within the body to form organ systems such as the cardiovascular system.
The health of the individual is intimately linked to the health of each organ system, organ and tissue, which depends ultimately on the correct functioning of the cells comprising each component. While the experience of ageing varies hugely between individuals, according to an inextricable combination of genetics, environment and lifestyle, it is an incontrovertible fact that people's physical and often mental functionality diminishes with increasing chronological age; whether one likes it or not, ageing is the single biggest risk factor for morbidity and death, and many older people are living with a range of co-morbidities (multiple different diseases) that seriously affect their quality of life and risk of death (Pilotto et al, 2012). For example, the primary causes of admissions to care homes are stroke, dementia and incontinence (van Rensbergen and Nawrot, 2010; Maxwell et al, 2013). Major killers in later life are cardiovascular disease (ischaemic heart disease and stroke) and cancer (WHO, 2014), usually involving a long period of ill health prior to death.
two - Understanding ageing: biological and social perspectives
- Edited by Alan Walker, The University of Sheffield
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- Book:
- The New Science of Ageing
- Published by:
- Bristol University Press
- Published online:
- 04 March 2022
- Print publication:
- 29 August 2014, pp 25-76
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Summary
Introduction
In this chapter, we discuss how social and biological studies of ageing can converge to provide a meaningful framework for progress in both understanding ageing and dealing with it in a positive manner. We start by discussing the meaning of the term ‘ageing’ and how it is in part defined by social context, and then, how psychosocial factors have an impact on both perception and the biological reality of ageing. From a theoretical perspective, we assess how ageing might have evolved, and how it is measured. The biological impacts of ageing are then described, moving from individual cells through tissues to major organ systems (immune, cardiovascular and nervous systems) (see Figure 2.1). What causes individual cells of the body to age is dealt with at both a cellular and molecular level, and we further discuss how studies of both extremely long-lived and short-lived humans have contributed significantly not only to our understanding of the biological processes of ageing, but also to the possibility of developing therapies to deal with the problems that cause greatest loss of quality of life in older age. We end by assessing the ethical case for intervening in those biological processes underpinning the development of those illnesses that so undermine health in later life.
Given the enormous scope and breadth of material that is covered, and the wide differences in perspectives and language used by the diverse disciplines that contribute to this chapter, we have tried to avoid jargon terms wherever possible, and provide simple definitions of unavoidable terminology as notes at the end of the chapter to assist the reader not specialist in that particular field.
Not ‘what’ is ageing, but ‘how’?
In order to study ageing in any meaningful way, we need to understand how the term ‘ageing’ is being used. To biologists, it can mean damage to molecules of the cell, and to cells of the tissue; to the physiologist, alterations in organ function; to the clinician, increased frailty and accumulation of diverse diseases. For the older person, ageing is felt and experienced, with changes in physical abilities and social activities and status having both positive and negative effects on the quality of their later life. Ageing is thus not so much a thing, but rather multi-dimensional, underpinned by complex social and biological processes, made up of many different mechanisms.