Men's body hair may indicate this

According to foreign media reports, in a new book, scientists Greg Brown and Mitchell Moffit answered many strange questions. For example, will cracking your finger joints cause arthritis? Why does snot turn green?

Is cracking your fingers bad for your joints?

Our bones are connected by ligaments, and the places where bones connect are joints. Cracking a joint actually stretches the joint and moves the bones away from each other. When the bones are stretched, the space inside the joint is increased, which reduces the pressure inside the joint. Joints such as the knees, elbows and fingers contain a special fluid that acts like a lubricant to reduce friction between the joints.

The low pressure in the joint caused by the stretching of the bones allows the gas in the special fluid, such as carbon dioxide, to quickly fill the newly expanded space in the joint and form bubbles. If the joint is stretched too far, the pressure in the joint will be too low and the bubbles will burst, resulting in a popping sound. It then takes 15 to 30 minutes for the gas to dissolve back into the special fluid, which is why you can't immediately crack the joint again.

Although there is no evidence that cracking joints causes arthritis, it is thought that frequent stretching of the joints may lead to decreased grip strength and damage to joint tissue.

Why does the sun make people sneeze?

Many people will sneeze if suddenly exposed to bright sunlight, a phenomenon known as the photic sneeze reflex. When the photic sneeze reflex occurs, nerve signals travel from the optic nerve through the trigeminal nerve, which controls much of the face—the eyes and eyelids, forehead, scalp, cheeks, jaw, teeth, chin, and even the outer ear. The resulting network of nerves prompts the "sneeze center" in the lower brain to initiate a sneeze.

When you sneeze, the brain sends sneeze signals to the muscles in the face, throat, and chest, which work together to produce a sneeze. Sneezing is usually used to get rid of irritants in the nose. But in bright light, the trigeminal nerve mistakenly tells the brain that the nose is irritated instead of the eyes, causing a sneeze.

Should you use the snooze button on your alarm?

Using an alarm clock's snooze button may do more harm than good. Typically, your body begins preparing for waking up an hour before you naturally wake up. Your body temperature rises, sleep becomes lighter, hormones such as dopamine and cortisol are released, and you gain energy to start a new day.

And alarm clocks not only interrupt your sleep cycle, but also shorten it, especially if you don't have a regular sleep habit. So when the alarm goes off, your body is not fully ready. This groggy state is called sleep inertia: the deeper the sleep stage you are in, the greater the sleep inertia.

What's worse, when you hit the snooze button, your body may reset the sleep cycle and enter a deeper stage of sleep. So instead of preparing to wake up, your body moves in the opposite direction. As a result, the second alarm may make you feel even more tired.

The solution to this problem is to develop a more regular sleep routine. You should wake up at the same time every day, including weekends, and after a few weeks your body will adapt to the new routine, reducing the need for an alarm clock.

Why does drinking coffee give you bad breath?

Our mouths are home to more than 500 different types of bacteria. These bacteria break down food residues and release volatile sulfides, which smell like rotten eggs. This process is like when milk leaves the refrigerator and bacteria begin to break down the protein in the milk, creating a sour taste.

Certain foods are better at stimulating bacterial growth. High-protein foods such as dairy products, meat and fish can be broken down into volatile sulfides, while alcohol and cigarettes, which dry out the mouth, can create an ideal living environment for bacteria. Coffee can provide an acidic and potentially sugar-rich environment, which can promote bacterial growth. And certain odorous foods, such as onions and garlic, contain sulfides themselves. These sulfides enter the human blood and are released through the lungs and pores.

Why does snot turn green?

A healthy nose produces about half a liter of mucus a day. Mucus is mainly composed of water, protein, carbohydrates and salts. It is mainly used to block dust, dirt and bacteria and prevent them from infecting the respiratory tract. Once these foreign objects are caught by mucus, humans can remove them by sneezing or blowing their noses, but more often they are processed in the stomach. This is because millions of tiny hairs in the nasal cavity push the mucus to the throat. When you swallow the mucus, the stomach acid in the stomach will clean up these uninvited guests.

When the cold virus enters the mucous membranes of your nose, your body fires up the mucus cells, sending more blood through your nose, which causes the cells to get more water, which results in a runny nose. At the same time, white blood cells containing potent chemicals are used to attack the virus or eat it up entirely. If your mucus is green, it's because of iron in enzymes in the mucus. Enzymes have a bactericidal effect, and the enzymes that make mucus green are the same enzymes that give the Japanese condiment wasabi its green color. (Wasabi was originally used to treat bacterial infections caused by eating raw food.)

Why can't my muscles get bigger?

The truth is, everyone has a limit to how big their muscles can get. Muscles are controlled by a protein called myostatin, which determines how big they can get. This limit is different for everyone and depends on the level of myostatin. When the limit is reached, myostatin stops any further growth. Low levels of myostatin result in bigger muscles. This is why some people's muscles swell easily but others don't.

Why do we feel numbness?

If you've crossed your legs and watched TV for hours on end, you've experienced very painful tingling in your hands and feet. The tingling is caused by a traffic jam in the nervous system. When you cross your legs or sleep on one arm, you cut off the blood flow to a particular nerve. The brain then senses that this nerve is being disturbed and increases the activity of that nerve, which results in a tingling sensation.

This tingling sensation can go away by removing the pressure and allowing blood to flow back to the nerves, but if the tingling continues, it could be a sign of a more serious problem that requires further evaluation by a doctor.

Why do men have more body hair?

Surprisingly, humans have a very similar number of hair follicles covering their bodies as our primate relatives. The reason we appear less hairy than our primate relatives is that most of our hair is thin and inconspicuous. This is because once our ancestors began to travel farther to obtain food and move into warmer environments, dense hair became a liability.

Men and women have roughly the same number of hair follicles. However, men have more terminal hair, which is longer and thicker than other hair (such as hair on the head and pubic hair). Men may also have terminal hair on their chest, back, toes, and ears.

Women have more vellus hair because it is more beautiful and smaller.

The reason for the difference in hair between men and women may be sexual selection. A hairy chest is a sign of health, which can attract female mates. Men may prefer women with less hair because it makes women look younger, which means they are healthier and more suitable for reproduction.

Can ice cream give you headaches?

While you happily anticipate the pleasures of cold drinks and ice cream, you discover that they can "freeze" your brain and make you very painful. This pain usually lasts for 20 seconds and occurs when the cold object touches the roof of your mouth. When you enjoy ice cream, the capillaries in the roof of your mouth will shrink. This is the body's normal reaction to cold as it tries to keep our vital organs warm.

But this is not the cause of the pain. The extra blood entering the brain to maintain temperature increases the pressure on the skull, causing headaches. In addition, when the cold substance is removed or swallowed, the capillaries in the mouth will expand rapidly, causing greater pain.