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 Effects of changing gravity on our bodies Life on Earth has evolved in the presence of gravity (G), and it plays a role in all life processes. G-force describes the way that changes in acceleration feel. We normally live in an environment of 1G. Environments where we might be exposed to changing G-forces include airplanes, fast elevators, roller coasters, swings, space launches, or the microgravity environment in space. Increasing G-forces push blood down into the legs and feet, reducing the amount of blood reaching the brain, which can eventually lead to a loss of consciousness. Between 2.5 and 4 G, one experiences grayout, where vision begins to fade, a result of a lack of blood to the brain. Beyond 4 G, blackout occurs. One regains consciousness when G-forces return to normal, but this is accompanied by confusion and even temporary amnesia for minutes to hours. To prevent blackouts, astronauts (and fighter pilots) wear an anti-G suit during re-entry (basically a series of inflatable bladders sewn into the pant-legs, which inflate with increasing gravity, thus preventing blood from pooling in the legs). During launch, they are positioned on their backs (perpendicular to the direction of acceleration) so that the G-forces do not push blood toward their feet. Orthostatic tolerance is the ability of the cardiovascular system to supply the brain with enough blood to maintain consciousness while an individual stands upright. When astronauts spend a long time in space, they often have dizziness or fainting spells for a couple of weeks after returning to Earth. The reason for these symptoms is orthostatic intolerance. In space, an astronautÍs cardiovascular system does not have to work against gravity, and so the blood vessels lose their ability to push against the weight of blood. On return to gravity, the system has a tough time keeping the blood flowing to the brain. Orthostatic tolerance may decline with aging. We may all have experienced it when we jump out of bed quickly in the morning. The direction of the G-forces on our body changes rapidly. We may feel dizzy until our heart and legs have had a chance to adapt to the change in our posture. Sitting on the side of the bed for a minute or so will prevent this from happening. A peril of life without gravity is bone and muscle loss. In space, astronauts can lose up to 2% of their bone mass each month. Their muscles and bones deteriorate up to 10 times faster than the rate seen in patients suffering from muscular dystrophy and osteoporosis. No one knows the molecular mechanism for this loss, and effective countermeasures have not yet been determined. In 1998, OSTEO-1, the Osteoporosis Experiments in Orbit-1, marks the first of a series of studies on bone loss in microgravity. The OSTEO-1 experiments were performed by John Glenn aboard Space Shuttle Discovery. The University of Toronto, Mount Sinai Hospital, Allelix Biopharmaceuticals, and Millennium Biologix Inc. also participated in the project, which was fully funded by the Canadian Space Agency. This year, the OSTEO-2 research project will continue with further studies on bone loss during spaceflight. When relieved of the pull of gravity as we sleep at night, the cartilage disks of the spine can expand about 1/3 of an inch. They shrink again with G-force pull during the day. How much G can the human body tolerate? This depends upon oneÍs age, fitness, hydration, body size, how long the force acts, the direction of G through the body, and whether an anti-G suit is being worn. The Guiness Book of Records cites: ´ On 13 July 1977 British racing driver David Purley survived a deceleration from 173 km/h to zero in a distance of about 0.66 m, enduring 180 G. ´ The beak of the red-headed woodpecker hits the bark of a tree with an impact velocity of over 21 km/h, subjecting the birdÍs brain to a deceleration of approximately 10 G when its head snaps back. 
Burton RR. G-induced loss of consciousness: definition, history, current status. Aviat Space Environ Med 59:2-5, 1988 Are we living barometers? Many animals and plants can sense changes in weather. Birds feel a drop in barometric pressure before the arrival of ñbadî weather and increase their foraging. Cats become restless, and ants prepare their mounds for the expected rain and wind. Some people claim they can predict weather based on how their bodies feel, and scientists have detected some physiological evidence that this may be true. Rapid changes in temperature affect blood pH, blood pressure, urine volume, and tissue permeability. Epidemics may also be related to sudden, large changes in weather conditions. A longitudinal study of 59 years of data demonstrated that sudden increases in influenza outbreaks in Germany, Norway, and Switzerland most frequently occurred between January and March, when cold air masses moved over the areas. Medical conditions that are sensitive to weather changes include: rheumatoid arthritis, osteoarthritis, low back pain, gout, fibromyalgia, phantom limb pain, scar pain, headaches, trigeminal neuralgia, and pain influenced by mood disorders. Weather is also associated with changes in birth rates, sperm count, outbreaks of pneumonia, influenza and bronchitis. Changes in weather can also induce short-term swings in mood, emotional well-being, and behavioural aberrations. Some of the meteorological variables implicated include: temperature, barometric pressure, rainfall, humidity, thunder-storm activity, sunshine, and the level of ionization of the air. Weather and Arthritis In advance of a cold front, we often see showers and thunderstorms, and a decrease in barometric pressure. In these low pressure conditions some people feel edgy and their arthritis flares up. For many, the symptoms precede any obvious weather change. Researchers have examined the relationship between weather and pain in people with arthritis. Although a link between changes in weather and changes in arthritic symptoms heavily relied on subjective assessments, such as pain, it appears that some people are weather-sensitive. However, scientific evidence is still ambiguous. Weather and migraines More than 50% of migraine sufferers say their headaches have a weather trigger. Relationships have been found between the numbers of reported migraine attacks and rapid changes in barometric pressure. A study by R.E. Cull reported fewer occurrences of attacks when barometric pressure was low. However, a Canadian Climate Center study (1981) found that migraines were most likely to occur on days with falling pressure, rising humidity, high winds, and rapid temperature fluctuations. Dealing with weather-related symptoms
There are scientific reasons for some of these symptoms Our body reacts to cold by constricting the blood vessels in the periphery, making the heart work harder. A significant drop in barometric pressure leads to an expansion of air in isolated body cavities and of fluids in membranes. This can injure tissues in joints or muscles, causing pain. Some people experience the same phenomenon during air travel when the cabin pressure drops during take-off. Another reason for weather sensitivity is the irritation of nerve ends from rapid changes in weather. In addition, bones and muscles have different densities. During temperature and humidity variations unequal expansion and contraction of these tissues may increase the pain in inflamed joints and injured muscles. Ill Winds In many cultures, seasonal winds are referred to as ñill windsî or ñwinds of depression.î Such winds are associated with feelings of anxiety, stress, depression and sleepless nights around the world. They have different names: foehns are dry southerly winds originating in the Sahara and blowing from the Alps across Switzerland and southern Germany. They are also called Mistral (southern France), the Sirocco (Italy), Sharav (Middle East), Hamsin (Arab), Chinooks (western Canada and USA), and Santa Ana (California Indian mythology). When these winds blow, temperatures can soar from freezing to 15°C in as little as two hours, and gusts clocked at 160 kilometres an hour can rip off roofs and topple trees. The winds are blamed for tension headaches, backaches, hot flashes, nausea and sleepless nights. Studies show that when foehns blow, traffic accidents and crimes increase, and suicide rates rise 20%. Sufferers say they know a foehn when they feel it. More than one-third of the 1,000 people surveyed by GermanyÍs Allensbach Institute said foehn-like weather noticeably affected their health. Why? Scientists aren’t sure why foehn makes people feel ill. It may be something about the air: its electrical charge, or ionization, and the balance of positive and negative ions. When exposed to negatively charged air, people report feeling positive and the opposite is true when the charges are positive. Warm winds bring positive ions, which shift the electromagnetic fields around us. When dry winds blow, dust attaches to negative ions and they lose their charge. Humidity, pollution, and high pollen counts also deplete negative ions. As long as the winds blow, the positive ions tend to accumulate. Check your ion balance There are a few cities where there are more negative than positive ions in the air: Niagara Falls, Canada; Sedona, Arizona; Mt Shasta, California; and Kauai, Hawaii. People living in these areas say they feel healthier. Apparently, a ratio of 5 negative to 4 positive ions produces a sense of well-being. Sick building syndrome is more common today than it was 20 years ago. Most homes and offices are built to be airtight and when the heating or air conditioner is running this causes friction, which depletes the negative ions. Consequently, only the positive ions are left to recirculate. Bacteria, mold, mildew and allergies thrive in positive ion air. Synthetic clothes and carpeting cause friction and deplete negative ions. Some natural fibers repel positive ions! Nature has its own way of creating negative ions; when it rains heavily negative ions are generated. ThatÍs why the air feels so fresh after a heavy downpour. References: Convertino VA. G-factor as a tool in basic research: mechanisms of orthostatic tolerance. J Gravit Physiol 6: 73-6.1999. Sonnenfeld G. Space flight, microgravity, stress, and immune responses. Adv Space Res 23:1945-53, 1999. Siegel SM. Gravity as a biochemical determinant.Life Sci Space Res 17:147-60, 1979. http://me.essortment.com/chinooks_rukk.htm Fletcher RJ. Fohn illnessî and human biometeorology in the chinook area of Canada. Int J Biometeorol 2:168-75, 1988. Hedge A, Collis MD. Do negative air ions affect human mood and performance? Ann Occup Hyg 31:285-90, 1987. Sher L. Effects of natural and man-made electric/electromagnetic fields on human health: a possible mechanism. Med Hypotheses. 49:31-4, 1997. Tromp SW. Medical biometeorology, New York: Elsevier. 1963. Berger F. Weathering MigrainesÜSevere headaches may mean you are literally under a cloud. www.healingwell.com Cooke LJ, Rose MS, Becker WJ. Chinook winds and migraine headache. Neurology 54: 302-7, 2000. Cull RE. Barometric pressure and other factors in migraine. Headache 21:102-3, 1981. Heat-related mortalityÜUS Public Health Service, Centres for Disease Control and Prevention. Dept of Health and Human Services, 1997. Kaiser M. How the weather affects your health. Pub. Michelle Anderson Publishing, Melbourne, 2002. Kalkstein LS. The impact of winter weather on human mortality. Climate Impact Assessment: United States, December, 21-23, 1984. Sanders JL, Brizzolara MS. Relationships between weather and mood. Journal of General Psychology 107: 155-156, 1982 |
 
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Increased irritability and aggressiveness, anxiety, depression,
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