Consequences of ageing Let's discus some very important consequences of ageing . As we age , concentration of water in the tissues decreases . To be more precise , the extra-cellular water in the tissues decreases , but the intra-cellular water in the tissues remain practically the same . A higher content of total water in the newborns is observed primarily due to the extracellular water ; with maturation , the total water decreases , i.e. as if the organism has become somewhat drier . the water loss is effected at the expense of extracellular fluids . Contents and distribution of water in human organism depending on the age ( % of total mass ) Age
Newborns Under 1 year From 1 to 10 years From 10 to 50 years Over 50 years
Total water 75 70 6065 5560 5055
Intracellular water 35
Outside cell Extra-cellular water 35
Plasm a 5
35 35-40
30 20-25
5 5
40-45
15
5
35-40
10
5
As we age , the thymus gland undergoes involution . Unlike the liver , kidney and heart , for instance , the thymus is at its largest in children . The thymus reaches maximum weight ( 20 to 37 grams ) by the time of puberty. It remains active only until puberty. Then with growing age , it starts to shrink . In old people , the thymus gland is scarcely distinguishable from surrounding fatty tissue . As man ages the thymus slowly shrinks , eventually degenerating into tiny islands of fatty tissue . By the age of 75 years , the thymus gland weighs only 6 grams . In children the thymus is grayish-pink in colour and in adults it is yellow . Any infectious disease and various stresses speed up its wear . Involution of thymus also occurs under the effect of external influences ( infections , starvation , burns etc. ) The thymus's function also changes as a person gets older . Initially it acts as a " teacher " Most of the immune cells , which occur within the marrow , cannot at first combat the body's enemies , but when they get into the thymus , influenced by specific substances , they become a regular army trained to fight viruses and tumors . Scientists call them " TLymphocytes " As the person ages , the thymus too gets older ; it can" train " fewer and fewer " T- lymphocytes " Hence , the body's own protective powers become increasingly diminished . In some people the thymus " wears out " sooner than in others ( The thymus gland is an important organ in antitumor immunity . It ensures the elimination of cancer cells due to its ability to suppress the synthesis of nucleic acids and proteins .The thymus participates in lymphopoiesis ( the formation of lymphocytes ) and immunological
defense reactions of the organism . The early loss of thymus function leads to the impairment of the immunological system . In thymus special lymphocytes called T-lymphocytes acquire certain properties which enable them to react defensively against cells that , for various reasons , have become foreign to the organism . In addition , the thymus intensively synthesizes DNA . ) During the ageing process , normal values of blood pressure changes .
systolic and diastolic
Normal values of systolic and diastolic blood pressure and relative age group Age group Newborns Children with age - 9 to12 Adults with age - 20 to 40 years Elderly people with age 50 to 60 or more
Diastolic blood pressure ( In mm Hg ) 34 70 65-80 65- 80 or slightly less
the
Systolic blood pressure ( In mm Hg ) 70 105 100-110 to 125 120
to 140
Note – The above measurements are taken during complete physical and mental rest . The heart-beat is faster in children than in adults , but the arterial pressure is low . The volume of blood in children is relatively larger than that in adults .According to different authors , it varies from 80 to 150 ml/kg ( 60 ml/kg in adults ). The blood flow rate in young children is about twice that in adults . The bone system undergoes great changes at old age . The number of bone lamellae ( parallel membranes of bony tissue ) reduces , and rarefaction of bone ( osteoporosis ) occurs . In addition , their is excessive formation of bone in the form of bone outgrowths ( osteophytes ) and calcification of the articular cartilage, ligaments ,and tendons at the site of attachment to the bone (excessive deposition of calcium in connective tissue and cartilagious structures adjoining the bone ). A one-third of the weight of the bone consists of organic matter ( mainly ossein and osseomucoid ) and remaining two-third is inorganic , chiefly , various calcium salts , calcium phosphate in particular ( 51.04%). The bones of young children , which , which contain comparatively greater amount of ossein , are marked by greater pliability , and their fractures are consequently rare . The resilience of bone depends on the presence of organic substances , while the hardness of bone depends on the presence of inorganic compounds . In contrast to young children , in old age, when the proportion of the organic and inorganic materials changes in favour of the latter ( the organic substances ( in %) decrease with age and the mineral salts increase ), bones become less elastic and more fragile .