Flashcards in Cellular Aspects of Ageing Deck (26):
What is 'normal ageing'?
The gradual and spontaneous changes that occur in maturation from infant to young adult, these changes create a normal physiological decline seen in middle and late adulthood
What are the consequences of ageing?
Reduced tissue/physiological function, decreased resistance to stress (physical and psychological) and increased susceptibility to disease (age-related diseases)
What different levels does ageing occur on?
Molecular, cellular, tissues and organ systems
What happens to the cells in cellular ageing?
Response to damage or stress can lead to apoptosis or arrested cell growth (senescence)
Why is there a balance between cancer prevention and ageing?
Apoptosis and senescence are mechanisms which prevent the development of cancer, but also work to facilitate ageing
What factors affect life expectancy?
Disease processes, medical treatment, lifestyle choices, nutrition, heredity
What are the two main groups of ageing theories?
Programmed theories (ageing has an internal biological clock) and error theories (ageing is a result of assaults that damage cells or organs so they no longer function properly)
What are telomeres?
Specialise DNA sequences at the end of chromosomes
What is the base sequence of telomeres?
What is the role of telomerase?
The enzyme which fills the gap in word down telomeres by attaching bases to the end of chromosomes
Describe the programmed senescence theory (telomeric theory of sensence) of ageing
Telomeres shorten with each cell division and when they become too short, this causes the cell to enter senescence; with ageing, telomerase levels decrease and the telomeres become shorter and shorter so more and more cells enter senescence
Describe the endocrine theory of ageing
Biological clocks act through hormones to control the pace of ageing, the hormones affect growth, metabolism, inflammation, stress and temperature
Describe the immunologic theory of ageing
A programmed decline in the immune system which leads to an increased vulnerability to disease, ageing and death
What is a free radical?
A molecule with an unpaired, highly reactive electron which works to grab electrons from any molecule in its vicinity and whilst doing this causes damage to the other molecule
What does the body have to defend against free radicals?
Natural antioxidants in the body e.g. Bilirubin, enzymes such as superoxide dismutase (SOD), catalase, and glutathione peroxidase and dietary antioxidants e.g. Vitamin E and C
Where are reactive oxygen species predominantly produced?
Mitochondria in oxidative phosphorylation
Describe the wear and tear theory of ageing
Years of damage to cells, tissues and organs eventually wears them out
Describe the rate of living theory of ageing
The greater an organisms basal metabolic rate, the shorter the life span
Describe the cross-linking theory of ageing
The accumulation of cross-linked proteins damages cells and tissue, and slows down bodily processes. There is loss of flexibility of connective tissue and there are micro vascular changes in arteries
Describe the catastrophe theory of ageing
Any damage to the enzyme systems that synthesise proteins in the body cause improper protein synthesis and these faulty proteins continue to accumulate until they reach a level which damages the cell/tissue. When enough damage accumulates, this may result in cell malfunctioning, which eventually leads to death
What is epigenetics?
Inherited and reversible modification to nucleotides or chromosomes that do not change the sequence but can alter gene expression
What heart changes occur with ageing?
Valves thicken and stiffen, number of pacemaker cells decrease, fatty and fibrous tissue increases around the SAN (can slow HR slightly), hypertrophy of left ventricle, heart may fill more slowly (therefore an increased role of atrial contraction is often required)
What changes in stem cells occur with ageing?
There is a decline in stem cell function with age, leading to stem cell exhaustion
How does the body's response to nutrients change with ageing?
•Nutrient sensing is a cell’s ability to recognise and respond to fuel substrates such as glucose but in old age, the homeostatic mechanisms involved in nutrient sensing decline which results in development of fat mass etc which have consequences for the development of other diseases e.g. Diabetes type II
How may calorie restriction improve life length?
Calorie restriction postpones senescence, and may also play a role in prevention of disease. There is some evidence that caloric restriction induces levels of some antioxidant enzymes and downregulates IGF-1