Don't Miss: Ten Scientific Tips Around You

There is a lot of scientific knowledge around us that we cannot think about. At present, we need to understand some scientific knowledge. There are many little secrets about people, such as:

Wait.

So why?

The following is an up-to-date information about ten little scientific knowledge around you that Xiaobian has compiled for you, hoping to help you.

Ten scientific knowledge around you:

1. Why do people yawn?

When we feel tired, body produces a lot of carbon dioxide. When there is too much carbon dioxide, oxygen must be added to balance body's needs. Since this residual carbon dioxide will affect functional activities of our body, at this time body sends a defensive reaction, so we yawn. Yawning is a deep breathing action that allows us to take in more oxygen and exhale carbon dioxide than usual, and also eliminates fatigue.

2. Why does hair turn gray with age?

There is a substance in our hair called melanin. The more melanin it contains, darker hair will be. And if there is little melanin, hair will turn yellow or white. When people reach old age, various functions of body gradually decrease, and production of pigment becomes less and less, so hair gradually becomes white!

3. Why do you growl when you're hungry?

When you're hungry, you'll grumble. This is because food you ate before is almost overcooked. Although stomach is empty, gastric juices in stomach will continue to flow. At this time, contractions of stomach will gradually expand, and liquid and gas inside will agitate, causing a gurgling sound. Don't be embarrassed that your stomach will growl next time, because this is a normal physiological action.

4. Why do babies cry after birth?

Babies wheeze when they are born, not because they are unhappy, but because they take their first breath! Air from mouth rushes into larynx, which hits vocal cords hard, causing vocal cords to vibrate. and make a crying sound.

5. Why don't you feel itchy when you scratch?

When others itch, we feel itchy and constantly laugh; however, when we scratch ourselves, not only do we not laugh, but we do not feel itchy either. Based on our mental preparation, brain sends message "no danger" and the nerves relax accordingly, so we won't laugh out loud and feel itchy!

6. Why do you get goosebumps?

There are fine hairs on surface of our skin, and under each pore there is a muscle that straightens hairs. It shrinks and makes hair stand up, forming goosebumps. In addition to its role as isolation, this physiological system can also make an animal appear larger than it really is, thus scaring off the enemy.

7. Why do women live an average of 5.86 years longer than men?

An important reason is that women have more opportunities to comb their hair than men, and more active combing can increase life expectancy.

The brain is central nervous system that directs and regulates various activities of human body. It has 12 pairs of nerves, about 10 billion cells, 5 arteries, 6 types of lymphatic vessels, 84 acupuncture points, and thickness of cerebral cortex is 2 to 3 mm, with a total area of ​​about 2200 square centimeters, with a growth of about 1 billion hairs. Maintaining mental clarity can prolong life. Combing hair is most ideal subject for brain training. Men often ignore its benefits: stimulating acupuncture points, massaging meridians, nourishing qi and blood, regulating functions, enhancing secretion, improving blood circulation, stimulating metabolism, conducting thought processes, combing hair can not only prolong life, but also make face rosy and fresh. .

9. Why don't people have one or three thumbs?

The average person has five fingers, and length of fingers can vary. However, has anyone noticed that, in addition to thumb, other fingers have three joints, and thumb has only two joints? .. It turns out that its number of joints is exactly same as other four fingers. If there are only three joints, thumb will appear weak and will not be able to lift heavy objects; if there is only one joint, it won't be able to interact with other four fingers to grasp objects freely!

10. Why do my eyelids bounce?

Twitching of eyelids is caused by stimulation of muscles around eyes. For example, prolonged reading, less sleep at night, inflammation of conjunctiva, eye irritation from strong light, etc.