Ageing

Ageing :-

• Gerontology is the branch of science that deals with ageing
• Ageing is also called as senescence
• Ageing may be defined as deterioration in the structure and function of the body cells, tissues & organs of an animal
• Hydra is an immortal creature being not to subjected to ageing
• Ageing is characterized by decline in metabolic activity.
• With advance age the efficiency of heart pumps decline
• Pumping capacity of 70 aged man as compare to 30 aged person is about 65%
• The declining of hearing starts after the age of 10
• On the average, 20% of nerve cells die at age of 70
• On 70s age, The number of uniferous tubule decline to half
• The part of lung which are mainly effected by ageing is alveoli, pulmonary artery, pulmonary vein
• Bones become brittle due to accumulation of calcium
• Ageing effect collagen which present in intercellular spaces become less permeable, rigid & insoluble
• 

Theories About Ageing :-

1. Compromise theory :- Acc to these biological ageing is an outcome of interaction between the genes & environment

Domestication leads to incease in life span

2. Immunity theory :- acc. To these theoty resistance of body decrease with increase in age

3. Waste product theory :- Acc. To these theory there are certain accumulation of substance in our body which leads to ageing

Facts :-

a.  Animal with high metabolic rate can die earlier than those of which having slow metabolic rate

b.  Women having longer lifespan than men

c.  Ageing process is faster in mens as compare to womens

d.  Acc. to one theory , decline in thymus gland in late middle age is primary cause of ageing