April 3, 2017Quiz
In humans, ageing represents the accumulation of changes in a human being over time, encompassing physical, psychological and social changes. Reaction time, for example, may slow with age, while knowledge of world events and wisdom may expand. Ageing is among the greatest known risk factors for most human 1) ___: of the roughly 150,000 people who die each day across the globe, about two thirds die from age-related causes.
The causes of ageing are uncertain; current theories are assigned to the damage concept, whereby the accumulation of damage (such as DNA oxidation) may cause biological systems to fail, or to the programmed ageing concept, whereby internal processes (such as DNA methylation) may cause ageing. Programmed ageing should not be confused with programmed cell death (apoptosis). The discovery, in 1934, that calorie restriction can extend lifespan by 50% in rats has motivated research into the delaying and prevention of ageing. On the other hand, very low-weight older people combating a disease, appear to have less resistance if they are too 2) ___.
In the 21st century, one of the most significant population trends is ageing. Currently, over 11% of the world's current population are people aged 60 and older and the United Nations Population Fund (UNFPA) estimates that by 2050 that number will rise to approximately 22%. Greater longevity has occurred, world-wide, due to better nutrition, sanitation, health care, education and economic well-being. Consequently, fertility rates have continued to decline and life expectancy have 3) ___. Life expectancy at birth is over 80 now in 33 countries. Ageing is a “global phenomenon,” that is occurring fastest in developing countries, including those with large youth populations, and poses social and economic challenges to the work which can be overcome with “the right set of policies to equip individuals, families and societies to address these challenges and to reap its benefits.” As life expectancy rises and birth rates decline in developed countries, the median age rises accordingly. According to the United Nations, this process is taking place in nearly every country in the world. A rising median age can have significant social and economic implications, as the workforce gets progressively older and the number of old workers and retirees grows relative to the number of young workers. Older people generally incur more health-related costs than do younger people in the workplace and can also cost more in worker's compensation and pension liabilities. In most developed countries an older workforce is somewhat inevitable. In the United States for instance, the Bureau of Labor Statistics estimates that one in four American workers will be 55 or older by 2020.
Changes With Ageing
The brain and nervous system are the body's central control center. They control your body's: movements, senses, thoughts and memories. They also help control the organs such as your heart and bowels. 4) ___ are the pathways that carry signals to and from your brain and the rest of your body. The spinal cord nerves run from your brain down the center of your back; extending out from the spinal cord to every part of the body. As humans age, the brain and nervous system go through natural changes, losing nerve cells and weight (atrophy). Nerve cells may begin to pass messages more slowly than in the past. Waste products can collect in the brain tissue as nerve cells break down. This can cause abnormal changes in the brain called plaques and tangles to form. A fatty brown pigment (lipofuscin) can also build up in nerve tissue. Breakdown of nerves can affect the senses; like reduced or lost reflexes or sensation, which can lead to problems with movement and balance. Slowing of thought, memory, and thinking is a normal part of aging. These changes are not the same in everyone. Some people have many changes in their nerves and brain tissue. Others have few changes. These changes are not always related to the effects on the ability to think.
Vital signs include body temperature, heart rate (pulse), breathing rate, and blood pressure. With ageing, vital signs may change, depending on the health of the individual. Normal body temperature does not change much with aging, however, it becomes harder for the body to control temperature. A decrease in the amount of fat below the skin makes it harder to stay 5) ___. Aging decreases the ability to sweat, hence, there may be difficulty sensing when the body becomes overheated. This puts older people at high risk of overheating (heat stroke) and also at risk for dangerous drops in body temperature. Fever is an important sign of illness in older people. It is often the only symptom for several days of an illness. A fever is also a sign of infection. When an older person has an infection, their body may not be able to produce a higher temperature. For this reason, it is important to check other vital signs, as well as any symptoms and signs of infection. With ageing, the pulse rate is about the same as before; however with exercise, it may take longer for the pulse to increase and longer for it to slow down afterward. One’s highest heart rate with exercise is also lower than it was when younger. Breathing rate usually does not change with 6) ___. But lung function decreases slightly. Healthy older people can usually breathe without effort.
Older people may become dizzy when standing up too quickly. This is due to a sudden drop in blood pressure. This kind of drop in blood pressure when standing is called orthostatic hypotension. Risk of having high blood pressure, or hypertension, increases with age. Other heart-related problems common in older adults include: very slow pulse or very fast pulse. heart rhythm problems such as atrial fibrillation. Medicines that are used to treat health problems in older people can affect the vital signs. For example, the medicine digitalis used for heart failure and blood pressure medicines called beta blockers may cause the pulse to slow. Diuretics (water pills) can cause low blood pressure, especially when changing body position too quickly.
Dementia and severe memory loss are not a normal part of aging. They can be caused by brain diseases such as Alzheimer disease, which doctors believe is associated with plaques and tangles forming in the brain and the buildup of lipofuscin. Delirium is sudden confusion that leads to changes in thinking and behavior. It is often due to illnesses that are not related to the brain. Infection can cause an older person to become severely confused. Certain medicines can also cause this. Thinking and behavior problems can also be caused by poorly controlled diabetes. Rising and falling blood sugar levels can interfere with thought. Mental and physical exercise can help your brain stay sharp. Physical exercise promotes blood flow to your brain. It also helps reduce loss of brain 7) ___. Some changes in the heart and blood vessels normally occur with age, but many other changes that are common with aging are due to modifiable factors that, if not treated, can lead to heart disease.
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The heart has a natural pacemaker system that controls the heartbeat. Some of the pathways of this system may develop fibrous tissue and fat deposits. The natural pacemaker (the SA node) loses some of its cells. These changes may result in a slightly slower heart rate. A slight increase in the size of the heart, especially the left ventricle, is not uncommon. The heart wall thickens, so the amount of blood that the chamber can hold may actually decrease despite the increased overall heart size. The heart may fill more slowly. Heart changes cause the ECG of a normal, healthy older person to be slightly different than the ECG of a healthy younger adult. Abnormal rhythms (arrhythmias), such as atrial fibrillation, are more common in older people. They may be caused by heart disease. Normal changes in the heart include deposits of the “aging pigment,” lipofuscin. The heart muscle cells degenerate slightly. The valves inside the heart, which control the direction of blood flow, thicken and become stiffer. A heart murmur caused by valve stiffness is fairly common in the elderly. Receptors, in blood vessels, called baroreceptors monitor the blood pressure and make changes to help maintain a fairly constant blood pressure when a person changes positions or is doing other activities. The baroreceptors become less sensitive with aging. This may explain why many older people have orthostatic hypotension, a condition in which the blood pressure falls when a person goes from lying or sitting to standing. This causes dizziness because there is less blood flow to the brain. The capillary walls thicken slightly. This may cause a slightly slower rate of exchange of nutrients and wastes. The main artery from the heart (aorta) becomes thicker, stiffer, and less flexible. This is probably related to changes in the connective tissue of the blood vessel wall. This makes the blood pressure higher and makes the heart work harder, which may lead to thickening of the heart muscle (hypertrophy). The other arteries also thicken and stiffen. In general, most elderly people have a moderate increase in blood pressure. Normally, the heart continues to pump enough 8) ___ to supply all parts of the body. However, an older heart may not be able to pump blood as well when you make it work harder.
All vital organs begin to lose some function, with aging, during adulthood. Aging changes occur in all of the body's cells, tissues, and organs, and these changes affect the functioning of all body systems. Living tissue is made up of cells. There are many different types of cells, but all have the same basic structure. Tissues are layers of similar cells that perform a specific function. The different kinds of tissues group together to form organs. Nerve tissue is made up of nerve cells (neurons) and is used to carry messages to and from various parts of the body. The brain, spinal cord, and peripheral nerves are made of nerve tissue.
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Cells are the basic building blocks of tissues. All cells experience changes with aging. They become larger and are less able to divide and multiply. Among other changes, there is an increase in pigments and fatty substances inside the cell (lipids). Many cells lose their ability to function, or they begin to function abnormally.
As aging continues, waste products build up in tissue. A fatty brown pigment called lipofuscin, collects in many tissues, as do other fatty substances. Connective tissue changes, becoming more stiff. This makes the organs, blood vessels, and airways more rigid. Cell membranes change, so many tissues have more trouble getting oxygen and nutrients, and removing carbon dioxide and wastes. Many tissues lose mass. This process is called atrophy. Some tissues become lumpy (nodular) or more rigid. Because of cell and tissue changes, organs also change with aging. Aging organs slowly lose function. Most people do not notice this loss immediately, because you it’s rare to use organs to their fullest ability. Organs have a reserve ability to function beyond the usual needs. For example, the heart of a 20-year-old is capable of pumping about 10 times the amount of blood that is actually needed to keep the body alive. After age 30, an average of 1% of this reserve is lost each year. The biggest changes in organ reserve occur in the heart, lungs, and kidneys. The amount of reserve lost varies between people and between different organs in a single person. These changes appear slowly and over a long period. When an organ is worked harder than usual, it may not be able to increase function. Sudden heart failure or other problems can develop when the body is worked harder than usual. Things that produce an extra workload (body stressors) include the following:
Loss of reserve also makes it harder to restore balance (equilibrium) in the body. Drugs are removed from the body at a slower rate. Lower doses of medications may be needed, and side effects become more common. Medication side effects can mimic the symptoms of many diseases, so it is easy to mistake a 9) ___ reaction for an illness. Some medications have entirely different side effects in the elderly than in younger people. No one knows how and why people change as they get older. Some theories claim that aging is caused by injuries from ultraviolet light over time, wear and tear on the body, or byproducts of metabolism. Other theories view aging as a predetermined process controlled by genes. No single process can explain all the changes of aging. Aging is a complex process that varies as to how it affects different people and even different organs.
A gerontologist does scientific studies of the biological, psychological, and sociological phenomena associated with old age and aging. Most 10) ___ feel that aging is due to the interaction of many lifelong influences. These influences include heredity, environment, culture, diet, exercise and leisure, past illnesses, and many other factors. Unlike the changes of adolescence, which are predictable to within a few years, each person ages at a unique rate. Some systems begin aging as early as age 30. Other aging processes are not common until much later in life. Although some changes always occur with aging, they occur at different rates and to different extents. There is no way to predict exactly how you will age.
ANSWERS: 1) diseases; 2) thin; 3) risen; 4) Nerves; 5) warm; 6) age; 7) cells; 8) blood; 9) drug; 10) gerontologists