The system of respiration in human, We think of respiration as being the job of the lungs – with help from the nose and the mouth. The lungs do collect and exchange gases (using blood cells as their couriers), but actually, every living cell in the body is involved in respiration.

What is Breathing?

Every day we breathe in and out 5,000 gallons (18,925 liters) of air. This respiration accomplishes two things. First, it supplies the body with oxygen, needed to burn food and release energy. Second, it expels carbon dioxide, a waste product of life processes. Oxygen, a gas that makes up approximately 20 percent of fresh air, is drawn into the lungs when you inhale. The exhaled air carries out excess carbon dioxide.

Though breathing is normally involuntary, you can consciously modify it – within limits. For instance, you can deliberately take big gulps of air before diving under water, you can also stop breathing voluntarily, but not for long; the involuntary reflexes forcing you to breathe are so strong that it is impossible to commit suicide by holding your breath.

What Happens When You are “Out of Breath”?

During violent exercise, your muscles may use up oxygen faster than your fast-pumping heart and lungs can replace it. Nature provides for this emergency by permitting the muscles to incur a short-term oxygen debt. Until the debt is repaid, you are in a sense “out of breath,” and you may continue to gasp for some minutes after extreme exertion.

What Causes Snoring, and Can It Be Cured?

The buzzing, rattling, wheezing noise called snoring is not a serious physical problem in itself, but it has often been a cause of marital discord. It is also to blame for countless bad jokes – and for the invention of some 200 gadgets designed to cure it. Snoring accompanies the sleep of one in seven adults, typically people who breathe through the mouth. The villain is the uvula, a pendant of flesh at the back of the mouth that vibrates as your breathing goes across it.

Most individuals who snore sleep with their mouths open because their throat or nasal passages are partly obstructed. Specific causes include nasal congestion, enlarged tonsils or adenoids, a nasal polyp, a deviated septum, loose dentures, or sleeping on the back, which lets the tongue fall back and partially close the windpipe.

Sewing a button onto the back of your nightclothes, one cure for snoring that dates back at least to the American Revolution, may discourage sleeping on the back, but it doesn’t necessarily solve the problem because people who sleep on their sides can also snore. Losing weight is sometimes helpful, since obesity can cause nasal congestion. Heavily salted foods can have the same result, so you should try to avoid eating them just before bedtime. The best remedy, however, may be earplugs – worn by the snorer’s spouse.

Why Do You Yawn?

If you see people yawning as they come out of the movies, don’t assume it was a terrible picture. Contrary to popular opinion, yawning is not necessarily a sign of boredom. If you yawn, it simply indicates that you need more oxygen, and it is nothing but a reflex that forces oxygen into your lungs.

The body’s oxygen supply is depleted after a long period of shallow breathing, which commonly occurs when you are tired, under stress, or have been sitting still for a long time. Yawning is not a sign of illness or abnormality. Oddly enough, yawning rarely occurs during serious mental or physical illness.

What is Passive Smoking?

In recent years, smokers and their opponents have exchanged numerous sharp words over smoking in public places. There is now plenty of evidence that smoking can harm not only smokers themselves but also the abstainers around them. As yet, doctors do not know how often so-called passive smoking causes lung cancer in nonsmokers. However, in a study of 2,000 nonsmokers, researchers turned up some interesting differences when they compared people who had little contact with smokers with those who regular breathed the “secondhand” smoke of others. In almost every case, the exposed nonsmokers showed some lung impairment, and after chronic exposure to heavy smokers, nonsmokers exhibited reduced breathing capacity.

Can Vitamin C Reduce Susceptibility to Colds?

The idea that vitamin C can ward off colds and reduce their severity has been popular since the early 1970s. The theory’s chief advocate, Dr. Linus Pauling, a Nobel chemist, claims that if you take 1,000 to 2,000 milligrams of vitamin C daily – and additional doses of 4,000 to 10,000 milligrams when a cold strikes – you will have fewer, milder, and shorter colds. His evidence includes the results of some experimental testing.

However, many specialists in upper respiratory infections have not found any definite indication that vitamin C substantially reduces the frequency or the severity of colds. Also taking large doses of vitamin C may have undesirable side effects.