Why should human nose? Because all animals, birds, there are only the nostrils are located on the mouth or mouth, and nose, as a separate body no.

I must say that the very posing of this question arouses bewilderment. Moreover, this unusual question deserves a more detailed consideration. Usually they say that this body is designed to smell, to pre-heat the inhaled air, although the same functions exist in other animals that have nostrils, a more developed sense of smell, but there's no separate body like the nose. Wasn't it in human ancestors, no nose and modern apes, including humanoid.

Humans are distinguished characteristic second signal system, the role of which in the activity of the brain is extremely high.

The animal irritation perceived only through the first signal system, through physical pain. A person has a strong negative effect on the brain can have a word that hurts sometimes stronger than any pain. The brain for damping, strong mitigation of negative impacts uses induction principle. When exposed to severe pain when frightened, strong nervous shock included protective system. Animals running, rushing about, shout, scream, jump. Similarly behaves and people. He, too, or goes from place to place, screaming, squeezes his teeth, biting of the lips or in any other way cause myself pain. These stresses reduce the impact on the affected area. That is why the day when a lot of distractions, the pain is better tolerated than at night.

If irritation or defeat above endurance threshold, then there "other" braking, with which the cell can do to stop taking the signals of external pressure. This can be faint, partial or total paralysis or pain or nervous shock. Hysterical paralysis can last for years or even a lifetime.

Very important here is the role of tears, mechanism of action which is that in the case of stressful situations, there is a new powerful compensating the main source of irritation. Activated strong irritation of the cerebral cortex increases a variety of bodily functions: breathing, motor, glands of internal and external secretion. Relaxes smooth muscles of urethra, rectum. That is why if a strong fear may happen involuntary urination or "bear's disease".

But above all, in any such case be included tears. Standing out from the tear glands, they tear-nose channels enter the nasal cavity and abundantly irrigated there mucous membrane. The last full of receptors trigeminal and olfactory nerves. Irritation of these receptors generates signals that travel to the brain, creating additional pockets of excitation. Whenever there is a strong shocks people cry, cry or scream, which also reduces the stimulation of the cortex of the brain.

In low endurance of the nervous system in cases of more or less strong excitations person faints. However, if you really irritate receptors of the internal cavity of the nose, for example, giving the man to smell ammonia, then the person comes to life.

People with weak activity of cortical neurons whining; the same can happen with age, when the endurance of neurons weakened, people become more emotionally sensitive.

Tired quickly many neurons of the cerebral cortex, and when a person sleeps, the neurons are disabled. If a long time not to disable, then people will sooner or later fall asleep, even in a very difficult position.

But such neurons, as those responsible for the activity of the respiratory centre, disabled and cannot work their whole life without stopping. Here it should be noted that these neurons periodically rest, so their work can substitute the work of other neurons. But if the load on neurons is too large, the backing of neurons may not be enough, and respiratory center can sharply reduce its operations or to stop it at all. That is why stops breathing when congestion, especially in untrained people. The fact that the voice folds of the larynx, which are in the normal state is pressed against the walls of the larynx, with fatigue weakened sharply than breathing difficult.

These phenomena can be observed and human nasal breathing. Stuffy nose can cause lag developing baby in both physical and mental development. You may receive in case of chronic nasal breathing disorders what is called "adenoid mask".

From the above one can see that nasal irritation should be permanent, and that dangerous as their excess and deficiency. Sometimes it is even recommended moderately advanced to annoy these nerve endings chemical or electrical stimuli. One cannot but remember nyange tobacco, the beneficent, the soothing effect of the smell of sea air, rich in ions in the air of coniferous forests, aroma of flowers, etc.

Moreover, as it became known at the present time, nose provides reflexive regulation of breathing and advanced regulates the blood circulation.

Because the nose is an indispensable accessory of the modern person as a consequence of the occurrence of the second signal system, it is possible that the size of the nasal bones suggest the height of steps in the development, on which stood the ancient ancestors of man, fossils of which fall into the hands of researchers.

The issue of blood: How in this viscosity, what is peculiar to the blood, the heart is unable to get rid of it all, even the smallest capillaries? Because the resistance of the fluid motion is inversely proportional to the fourth power of the radius of the pipe through which it flows.

Indeed, the blood of humans and animals has viscosity comparable to the viscosity of glycerin.

In 1661 Marcello Malpighi, and after a while and Anthony Leeuwenhoek found in living tissue microscopic capillaries, and then red blood cells, and were called in Greek - erythrocytes - "red cells". They are the basic volume of the cells contained in blood, and give it the color red. The blood, thus, is the suspension, where its cells make up almost half of the volume, which is the hematocrit or hematocrit. For a man this volumetric rate equal to 45.5%.

For suspensions cannot be satisfactorily described by conventional hydrodynamics. Be referred to the cells of solid particles of the same size, the viscosity of the blood would increase by 500 times.

But awesome is that blood flows; and at the specified hematocrit its viscosity is only three times higher than the viscosity of water, and when the hematocrit 85% of it only in 50 times higher than the viscosity of water.

Red blood cells in the normal state overlook biconcave lenses, there are a disc with a diameter of 8 microns, concave on both sides in the middle. Maximum thickness of the disc - 4, the minimum is 2 microns. Within the membranes of erythrocytes is its liquid content - cytoplasm. The kernel of the erythrocyte not.

The structure of the cells allows it as needed to change its shape in the process. Especially when driving in narrow capillaries, whose diameter is less than the diameter of a red blood cell. Here she takes streamlined bullet and move in concert, one after another.

In normal blood vessels movement of erythrocytes ahead of blood flow in General. This is because the red blood cells in the blood flow concentrated in the Central, the fastest part of the channel.

Lives erythrocyte only 4 months, and then dies, and liver and spleen withdraw them from circulation. An aging erythrocyte not able plastically to change its volume, as do young or Mature, therefore, the age of getting old cells in narrow channels is becoming less likely. Dying cells in the blood are related to the spleen - "the cemetery of erythrocytes".

The membrane of erythrocytes very strong and plastic; as if it is able to flow, acquiring some form. Thus, the cell is pseudosida that, if the movement does not have a strong resistance movement.

As with normal blood flow speed maximum in the center and practically zero at the walls, the different parts of the disk of the erythrocyte be under the influence of the layers, moving at different speeds, the erythrocyte starts to move. But moves erythrocyte not like a wheel, like a caterpillar tractor.

Thus, fluid membrane practically does not create hydrodynamic resistance, and blood has a much lower viscosity than would be expected, whether erythrocyte rigid or flexible.

Studies have shown that red and white blood cells and other blood cells carry on its surface a negative electric charge. And on the inner surface of the blood vessel is formed charge of the same sign. Thus, particles of blood and its components do not come into contact with the walls of blood vessels.

In case the vessel is broken, as in this place the charge changed to the opposite, and negatively charged particles of blood immediately settle in this place and plug the hole. Moreover, created the potential difference leads to coagulation of colloidal particles, that process of healing will further accelerate.

In addition it should be noted that recently found another detail of blood flow. It turned out she moves not a live stream, as it was considered, and its particles in motion have a spiral trajectory, that is, its flow is twisted. This thread, as the authors of this discovery, etc M.N. Ushurov and RAMS academician Century Shumakov, prevents blood particles to stick together and prevents blood clots. It is also established that flows in the large and small circles of blood circulation rotate in different directions.

How many people lived on the Earth?

Since then, how on Earth there are people born more than 78 billion people. Currently on our planet lives of almost 6 billion. This represents approximately 4% of the total number of people who lived on Earth during the existence of mankind. The calculations of American scientists Rollier and Floriana developed from time 600 000 years BC and went through it to our time.

"Man cannot breathe, this is not consistent with the known laws of physics" - said in 1929 Swedish scientist Kneeled. What is the matter?

The scientist has held the appropriate calculations and came to the conclusion that the pressure in the lungs of a person should exceed the actual and measured experimentally almost 10 times, and existing respiratory muscles will not allow the person to make even one breath.

In order to understand the reasons for this paradox, it is necessary to refer to evolution. For small primitive organisms, who had also low body temperature was quite enough of oxygen, which was received in their body through external cover. But with the growth in size, and hence the mass of organisms oxygen demand grew rapidly. So, for every kilogram of body weight a warm-blooded animal needs not less than 1 m2 of surface gas exchange. To meet this need was formed a special body - lungs.

In normal view is a kind of air bellows, which, with breath filled the air, and when exhaling the air in their lungs out. It turned out to be completely fair, if to speak about Ptichka to man the area of gas exchange should be approximately 75 m2. The chest should be an immense size, almost reaching the railway carriage. Light people have dendritic structure, that is, resemble a tree with a branching crown. From the main trachea, vetas 24 times, depart smaller and smaller tubes. At the end of each tube is a bubble - socket. The radii of the alveoli are small and do not exceed 0.05 mm, and the number is up to 300 million.

This structure leads to light when their small volume have a huge surface of gaseous exchange, which, if it prosummirovat, would cover a tennis court.

But the reduction of the diameter of the alveoli comes at a certain stage with the forces of surface tension. Yet Pierre Simon Laplace investigated these forces, and why they received the name lapesova. So, to blow a bubble need to overcome the greater the resistance of these forces, the smaller the radius of the bubble.

Neergard suggested that if the actual size of the alveoli should kazatsya surface tension of the available water in the lungs. Putting the coefficient of surface tension of liquid alveoli (= 50 Dyne/cm, the radius of the alveoli r is equal to 5*10-3cm, the scientist has received the amount of pressure needed to maintain the alveoli in this expanded state - 20 000 Dyne/cm2.

This curious conclusion no one seriously was not accepted until this issue is not interested Englishman Pets. He drew attention to the fact that foam bubbles, acting on the lips of people, for example, epileptics during an epileptic fit, persist for a long time, much longer than usual soap bubbles. Exploring this liquid Patel came to the conclusion that in alveoles fluid contains surfactants. These substances - surfactants - reduce surface tension in several times. They greatly reduce the opposing breathing lapesova pressure, allow to co-exist in the structure of the lungs parkam of different diameter. All the alveoli, moreover, soobschaetsa among themselves, resulting in them is supported by one pressure. If not surfactants, due lepesovkha pressure small alveoli sought would further reduce its size, and the large consequently prohibitively would have been flared.

The experiments showed that the surfactants reduces the surface tension with smaller surface of the bubble. These studies have allowed us to take another look at the phenomenon of the difficulty first breath in the newborn infant. Guilty for this was the lack surfactant. Prudent introduction of these substances into the organism of the mother before the birth of a child can cope with this difficulty.

Why would fingers?

Habit in moments of excitement to pop your fingers quite common among people. But only recently became known, the reason of this phenomenon. It was assumed that this crack generate bones, according to another version - ties of the joints. To study the nature of this phenomenon English scientists have designed a special device which pulled the fingers at a certain speed, and strength. It was something like a medieval torture chamber, which have been tested for about twenty volunteers. But unlike the victims of the Inquisition, with subjects nothing terrible has happened. Tensile fingers were produced x-ray joints.

Studies have shown that stretching the joint increases the amount of the articular capsule; pressure it falls. This leads to the effect oil" fluid, resulting in it there are bubbles of gas. Pressure continues to fall as stretching of joints, bubbles burst. But out of gas because the joint is sealed. When returning the joint in the same position again dissolved gas in the liquid. Return to starting position takes about 15 minutes. The joint should "relax" before he will acquire the ability to "shooting".