Anti aging guide

Body composition and Changes in function

 

 

What changes in our body function when people grow older?

As people grow older there is a gradual reduction of all active tissues, including brain, heart, lungs, liver, kidney, muscles, and bone. By middle age some decrease in muscle power and stamina must be accepted, and even athletes cannot compete on equal terms with those 15-20 years younger. In many sports the middle-aged are regarded as ‘veterans’, for example at 40 years for women and 45 for men in tennis. Persistent exercise slows down the rate of muscle and bone loss but seems unable to prevent it altogether. By age 80 most people have lost about half their muscle mass and replaced it by fat. Provided this does not increase weight overall, the gradual increase in fat is not harmful, and in truth its presence can prevent an otherwise scrawny appearance.

The general chemical activity (metabolism) of the body, which is highest in infancy, also declines throughout life. To avoid putting on too much fat it is necessary to reduce food intake from middle age onwards, even for the physically active. If you take very little exercise, your energy requirement at absolute rest actually accounts for most of your energy requirement. Since most of the energy in food is in fats and carbohydrates (and in alcohol for those who drink it liberally), these especially must be curtailed. The intake of fresh fruit and vegetables should be maintained.

An imperceptible decline in many functions affects us after the age of 25-30 years. By middle age there are measurable declines in vision, hearing, and the speed of response to mental and physical challenge. Physical stamina (but not sight or hearing) can be maintained to a considerable extent by keeping active.

Aging of the nervous system
The nervous system has an unique role in our ability to function at both a social and a biological level. In our 60s and 70s we all suffer some slowing of the thought processes and some impairment of memory (`benign senescent forgetfulness’) but nevertheless can cope well with all we need to do. Loss of active cells and of supporting tissue affects some areas of the brain much more markedly than others. Fortunately, reserve capacity is so great that cell loss solely from aging appears to cause little embarrassment.

Malfunction rather than just loss of cells accounts for much of the trouble with an aged brain. This may be due to inadequate production of neurotransmitters. These substances transmit signals from one nerve cell, or neuron, to another, and so from one part of the brain to another. Neurotransmitters also permit brain cells to communicate, via neurons in the spinal cord and peripheral nerves, with different parts of the body, including muscle, bone, and skin. The integrity of the nervous system is vital to the maintenance of homeostasis, or constancy of the internal bodily environment in the face of external change.

Vision
Loss of elasticity of the lens of the eye occurs progressively throughout life and by middle age most of us are aware that reading books, newspapers, etc. is increasingly difficult. Spectacles may be needed for the first time and either bifocal or multifocal lenses may be required. Color discrimination becomes less good and adaptation to darkness is also impaired, which affects night driving. In the home and in public places good levels of illumination and bold contrasts of light and dark are required to allow for safety in movement and especially to avoid hazards such as changes in floor level.

Hearing
Hearing also deteriorates, especially for high-pitched sounds but it is not clear how much of this can be attributed to trauma from the noisy environment. The loss is detectable by special tests years before we ourselves become aware of it, usually in middle age. It is not the loudness of the spoken word which is the problem so much as lack of definition of each separate word. The words sound `fluffy’ because consonants, which are high-pitched sounds, are not properly heard. Background noise compounds these hearing difficulties, so that conversation while traveling or in groups is particularly tiresome. Reduced direction-finding for sounds and poor comprehension of frequently interrupted speech make for extra difficulty in general conversation.
New names of people or places are demanding because the context offers no clues (`Was it Mrs McCave or Mrs McCabe who telephoned?’). Names such as these can be virtually indistinguishable, yet some people find it embarrassing to ask the caller to spell out the name slowly, distinctly, and preferably using the international phonetic voice procedure (i.e., Mike Charlie, Charlie, Alpha Bravo Echo) or a homely variant. Much of the problem of comprehension relates to slower data processing in the brain, therefore unhurried speech is better heard. Fast talkers tend to blur their consonants and run words into one another which frustrates elderly listeners.

Balance
The eye and ear both have to do with balance but neither is crucial in keeping us on our feet. Furthermore, the ability to maintain an upright posture may fail even with quite good eyes and ears. The vestibular (balance) part of the ear shows a less severe functional decline than the cochlear (hearing) part. However complaints of dizziness have been observed to be more common in older subjects, affecting about 40 per cent of men and 60 per cent of women over the age of 65 years.
Balance becomes less secure in later life. To stay on our feet we depend upon the integrity of many different parts of the brain and spinal cord, as well as on sensory inputs from mechanoreceptors which detect movement in the muscles and joints. Weakness or stiffness in the muscles or joints further impairs posture control and especially the ability to correct sudden displacements from the upright position. Adequate vision does aid balance but in the dark this compensation fails. Nevertheless, most falls occur during the day when we are up and about.

Heart and circulation
The capacity for pumping blood around the body is reduced at rest and during exercise. However those participating in regular strenuous activity preserve more of their exercise capacity. Blood pressure tends to be higher in older, westernized people but not in all cultures. After the age of about 70 the pressure tends to level off and it is not entirely clear why this is so. One possibility is that those with the higher pressures have already died from stroke, heart disease, or other cardiovascular disorder.

Lungs
As age increases, our lungs and chest wall become less elastic and our maximum breathing capacity is reduced. The mechanisms protecting the lungs from infection, such as ciliary action and normal mucus production, become less effective making us more liable to chest infection. There is less efficient gas (such as oxygen and carbon dioxide) exchange in the tiny air spaces (alveoli) of the lungs. For a given level of physical effort, we have to breathe much harder to maintain a satisfactory blood oxygen level. Not surprisingly, elderly people become breathless more quickly on exercise. They are readily upset by a lack of oxygen and show adverse effects to high altitude more quickly or, if not acclimatized, at a lower level, for example at 2100 meters (less than 7000 feet). Age changes in the lungs are all greatly overshadowed by the adverse effects of cigarette smoking and atmospheric pollution.

Kidneys
The kidneys shrink as we age. Each kidney consists of numerous subunits called nephrons which collectively cleanse the blood of impurities. This collective function of the nephrons declines, as does the blood supply to the kidneys; additionally, the nephrons die off. As a result of these changes, renal function in old age may be markedly impaired. This is not normally troublesome but when illness strikes, poor kidney function can cause major problems.

Posted by Carol Hudgens - April 25, 2012 at 4:55 pm