Category Zoology

Why should I breathe through my nose?

            Breathing through your nose filters and warms the air that passes into the lungs. The air breathed into the passages behind your nose flows over thin bones. These are covered with sticky mucus, in which dirt particles are deposited and later swallowed. This stops your lungs from getting filled with dirt that cannot be removed. Sometimes people such as coal miners breathe in so much dust that it cannot all be filtered out. This can sometimes cause lung disease, such as emphysema.

Why is it harder to breathe when you are up a mountain?

            At high altitudes that air is thinner so there is not so much oxygen in it. This means you will breathe heavily if you exert yourself by climbing. Some mountaineers carry oxygen cylinders to help them breathe. In aircraft, air is pumped in under pressure so that passengers can breathe at high altitude.

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Why do I sometimes cough?

            Coughing is the way in which the lungs dislodge anything that blocks the air passages. Usually these are only minor blockages caused by a build-up of mucus when you have a cold or chest infection. When you cough, your vocal cords press together to seal off the air passages. At the same time your chest muscles become tense, raising the pressure in your lungs. When you release the air it rushes out, carrying the obstruction with it.

How does smoking harm the lungs?

            Smoking damages the natural cleaning mechanism of the lungs, and also poisons the cells that line the lungs. Tobacco smoke paralyzes the tiny beating hairs inside the air passages of the lungs. These hairs normally clean out any material that is inhaled. Tar from the smoke accumulates inside the lungs, together with small grains of soot and chemicals that can sometimes cause cancer. These substances are absorbed into the blood and can cause damage to the heart and circulation.

            Regular smokers often suffer from lung diseases such as bronchitis, which are caused by irritation of the lungs by tobacco smoke.

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Can I breathe out all the air in my lungs?

Normally you only breathe out about 10 percent of the air in your lungs. If you are running and panting very hard you may use up to 60 percent of the air, but at least 20 percent will always be permanently trapped in the alveoli. You breathe faster and deeper when you exercise in order to get more oxygen into your body. This helps to break down sugar and provide energy for your muscles to work.

How is air passed in and out of the lungs?

Most of the airflow in the lungs is caused by the contraction of a sheet of muscle called the diaphragm. It is a curved muscle sheet that separates the contents of the chest from the abdomen. As the diaphragm contracts and flattens, the volume of the chest is increased. This causes the pressure inside the lungs to drop, so air rushes in. When the diaphragm relaxes it becomes curved again and forces air out of the lungs. The chest also helps in breathing when you take vigorous exercise, and the ribs are moved in and out by muscles that run between them.

How long can you hold your breath?

Most healthy people can hold their breath for about 90 seconds, but it soon becomes very uncomfortable. You normally breathe automatically, and never have to think about it. This is because there is an area in the brain that controls breathing. Normally the brain detects the build-up of waste carbon dioxide if you exercise. It speeds up breathing to get rid of it quickly by flushing it out of the lungs. If you try to hold your breath you can override this mechanism for a while. However, the brain will not let carbon dioxide builds up too much and will soon force you to breathe.

How can people breathe underwater?

            You can breathe through a snorkel if you are swimming on the surface. It would not be possible to suck air down a snorkel if you were 1 m under water. The pressure of the water would prevent your lungs from expanding enough to draw the air in. divers use compressed air to breathe. It is fed to them by a valve that automatically provides air at exactly the same pressure as the surrounding water, no matter how deep they dive, so they can breathe easily.

            Some divers who need to work at great depths have to breathe a special mixture of gases, because nitrogen and oxygen become poisonous at very high pressure. The mixture of gases is adjusted automatically to provide the correct amounts.

How do I breathe?

When you breathe, you draw air in through the nose and mouth and into the lungs. Air consists of 79 percent nitrogen and about 21 percent oxygen, with small amounts of carbon dioxide and other, rare gases. Air travels down a tube called the trachea that forks into other tubes called bronchi, which lead into the lungs. From here the air passes into a series of smaller air passages and eventually into tiny air sacs, or bladders, called alveoli. Oxygen is absorbed through the thin walls of the alveoli into the blood, and waste carbon dioxide is released to be breathed out as a waste product.

How big are the alveoli?

Each alveolus is about 0.2 mm across. The walls of the alveoli are very thin — only one cell thick — so oxygen and carbon dioxide can easily pass through. There are probably 300 million alveoli in the lungs.

Why do many of my muscles work in pairs?

                A muscle can only pull in one direction. It needs another muscle to pull in the opposite direction in order to return a bone to its original position.

                When you lift your forearm, the biceps muscle shortens to lift the bone. When you straighten your arm, the triceps muscle pulls it back again and the biceps relaxes. The same action takes place in your legs when you walk and run, and when you move your fingers and toes.

What causes muscle cramp?

                      Cramp is caused by the build-up of a waste substance called lactic acid. When a muscle works harder than usual, it starts to break down stored food without using oxygen. This process is called anaerobic respiration. It produces lactic acid as a waste product. As the lactic acid builds up it interferes with muscle action, making the muscle feel tired, until the acid is flushed away by the blood. If too much lactic acid builds up, it makes the muscle contract very sharply and painfully, causing a cramp.

How does regular exercise help the muscles?

                 Muscles are able to adapt gradually to the amount of work they have to do, so regular exercise can build them up and make them healthier. Exercise strengthens the muscles and improves muscle tone. It can also improve your body shape and posture, as well as strengthening your heart and improving your blood flow. It will generally make you feel much better and help you to sleep soundly.

How do muscle fibres shorten?

Muscle fibres contain tiny rod-like structures that overlap. When the fibre receives a nerve signal that tells it to contract, these rods slide over one another, making the fibre shorter. As the fibres shorten, the whole muscle contracts. All the fibres do not contract together. The harder the muscle needs to pull, the greater the number of fibres that will contract at the same time.

Can I make my muscles grow?

Muscles react to frequent exercise by growing more muscle cells, or fibres, making the muscle thicker and more bulky. The more fibres there are in a muscle, the stronger it will be. This explains why athletes who take constant exercise develop very large muscles.

How many muscles do I have?

You have about 650 muscles in your body. There are more than 50 muscles in your face alone.

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