Category Human Body

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.

The delicate alveoli inside the lungs can be damaged by many different things, thus causing us to cough. One is tobacco smoke, which clogs the alveoli and airways with thick tar. Others are the polluting gases that hover in the air of many big cities, coming from vehicle exhausts as well as factory and power-plant chimneys. Some types of industrial dust and particles floating in the air, such as asbestos or coal-mine dust can cause considerable damage to the lungs.

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Respiration, or breathing, is when you draw air in through the nose and mouth and into the lungs. Like all movements in the body, those of respiration rely on muscle power. There are two main sets of breathing muscles: the intercostal muscle and the diaphragm. Breathe in deeply and watch your ribs rise and your chest expand. Together these muscles make the chest bigger and stretch the spongy lungs inside. As the lungs enlarge, they suck in air down the windpipe. This is how we breathe in. Then the muscles relax. The ribs fall back down and the diaphragm resumes its domed shape as the spongy, elastic lungs spring back to their smaller size. The lungs blow some of their air up the windpipe. This is how we breathe out.

The movements of breathing are controlled by the brain. It sends out signals to make the muscles contract. The signals pas along nerves to the intercostal and diaphragm muscles, making them contract. This happens every few seconds throughout our life, even when you are asleep.

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A baby begins as a fertilized egg – a pinhead-sized egg cell from the mother, which has joined an even smaller tadpole-shaped sperm cell from the father. Although thousands of these sperm cells may cluster around the egg cell, only one of these will actually fertilize the egg.

Non-identical twins are produced when two eggs are released at the same time, and both are fertilized. They can be the same sex, or brother and sister.

Identical twins are produced when the embryo splits into two in the early stages of its development. This produces two identical children of the same sex. Some identical twins look so alike that they can only be told apart by their fingerprints.

Only one in 83 pregnancies results in twins.

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At about 280 days after the baby’s inception, the mother starts to feel strong tightening pains, called contractions, in her womb when the birth is near. These contractions become stronger and the neck of the cervix starts to open. As the contractions continue, the baby’s head moves down and eventually emerges through the cervix and vagina.

A breech birth is different to a regular birth because the buttocks engage in the pelvis instead of the head. This makes delivery more complicated as the largest part, namely the head, is delivered last. A breech birth is encountered about once in every thirty deliveries. Because the head in such cases is the last part of the child to be delivered and because this part of the delivery is the most difficult, the umbilical cord may be compressed while the after-coming head is being born, with the result that the child may be deprived of oxygen.

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The part of the brain that analyzes messages coming from the receiver cells in the nose is closely connected with the limbic system, that part of the brain that deals with emotions, moods and memory. It is called the primitive brain, sometimes even the ‘smelling brain’. The connection explains why smells are richly supplied with emotional significance. The smell of fresh-baked bread may bring on instant pangs of hunger, while the scent of perfume may remind you of a loved one. On the other hand, unpleasant smells such as rotten eggs, produce revulsion and sometimes even nausea.

Certain smells will bring memories of long forgotten special occasions flooding back. This is because the areas of the brain which process memories are also closely linked to the limbic system, which in turn is linked to the areas in the brain that control the sense of smell.

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Close your eyes and touch something, such as your clothes, a table, a car or even your own skin. Stroke it gently. What does it feel like? Is it hard or soft, hot or cold? The surface may be smooth, bumpy, gritty, furry or hairy. It could be dry, moist, or slimy. Your skin continuously passes huge amounts of information to the brain. It monitors touch, pain, temperature and other factors that tell the brain exactly how the body is being affected by the environment. Without this constant flow of information, you would keep injuring yourself accidentally, which is what happens in some rare diseases where the skin senses are lost. Senses in the skin are measured by tiny receptors at the ends of nerves. There are several different types of receptor. Each type can detect only one kind of sensation, such as pain, temperature, pressure, touch and so on.

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