Body temperature limit: How low can your body bear the core body temperature?
Usually, the body temperature is above 37℃, even if the body temperature drops only a few degrees, the body will immediately produce various discomfort symptoms caused by "hypothermia". When the core temperature drops to 36℃, your reaction and judgment will be weakened; When the body temperature drops to 35℃, you will be unable to write your name with a pen, and even it is difficult to walk; When the body temperature drops to 33℃, you will become completely irrational, you will throw away all survival tools and even take off your clothes; When the body temperature drops to 32℃, most people will collapse; When the body temperature drops to 30℃, most people will fall into a coma. At this time, your body will give up maintaining core body temperature, and your breathing will be reduced to 1-2 times per minute.
When the core temperature drops to 28℃, you will have arrhythmia; When the body temperature drops to 20℃, the heart will stop beating completely. However, even so, doctors can't declare "you are dead" because extreme low temperature will also slow down the disintegration and death of human cells. If your body can gradually warm up, or rescuers use a defibrillator to rescue you, then you still have a chance to "resurrect".
Up to now, the lowest "core body temperature" recorded in history is 16℃. British scientists believe that the absolute minimum "core body temperature" that the human body can theoretically bear can be as low as 0℃ or above, but once it reaches 0℃, ice crystals will form in your body organs, thus destroying all cells, and you will never "resurrect".
Impact limit: How much impact can your body bear?
Scientists have found that each muscle fiber of human muscle tissue can generate a force of 0.3 micro Newton, that is to say, every square centimeter of human muscle can bear the pressure of 100 Newton (about 10 kg). However, if the pressure on the human forearm exceeds 200 MPa, which is equivalent to about 50 kilonewtons (about 5,000 kilograms), bones will start to break.
Although the maximum theoretical impact force that the human body can bear is 50 kilonewtons. But at present, the recorded "human body limit" is only 3000 Newton. The boxer's body is usually the body that bears the greatest impact. 193 1 year, max baer, an American boxer and world heavyweight champion, made the deadliest punch in boxing history in the confrontation with his opponent Ernie Schiff, who never fully recovered and died six months later.
The probability that pedestrians survive being hit by a car usually depends on the speed of the car. Most cars are designed to protect passengers, not pedestrians. If the speed of a car hitting a pedestrian is about 30 ~ 45 kilometers per hour, the probability of pedestrians surviving will be as high as 87%; When the speed is as high as 45-50km/h, the survival probability of pedestrians being hit will drop to 27%; If the speed exceeds 60km/h, the survival probability of pedestrians being hit will never exceed 1%, because the muscles and bones of ordinary people can never bear the huge impact force at such a high speed.
Blood loss limit: how much blood does the human body lose to survive?
As we all know, blood is the fuel of life, and life depends on blood. A healthy adult has about 3.8 ~ 5.6 liters of blood. If the average human body loses 65,438+05% of the total blood quickly, there will be no direct impact. However, if the blood loss exceeds 15% of the total blood volume, your pulse will be accelerated, and your body will also have various adverse reactions such as dizziness, irritability or chills.
Studies have shown that when the blood loss exceeds 40% of the whole body volume, the blood pressure will become too low to return to the atrium, and the heart will have symptoms of "ventricular tachycardia", which usually has fatal consequences. Once the human body is injured and loses too much blood, lying down and keeping calm will reduce the level of adrenaline, thus delaying the time of shock.
Scientists believe that, in theory, the human body can lose 50% of its blood (about 1.9-2.8 liters) and still survive. The historical record of "extreme blood loss" is as high as 75%.
Tolerance limit of spicy food: How spicy food can your tongue and gastrointestinal tract tolerate?
The tongue and gastrointestinal tract of the human body often have extreme reactions to spicy food. At present, the hottest food is red pepper and curry rice, because these foods all contain "capsaicin". Although capsaicin does not directly cause chemical cauterization or directly damage cells and tissues, it stimulates human nervous system so strongly that it is similar to an extreme allergic reaction. In addition to enduring unimaginable pain, the human body will shed tears and have a runny nose uncontrollably. In addition, there will be spasms in the upper body, and symptoms such as dyspnea will last for 30-45 minutes.
At present, the record limit of pure capsaicin that human body can bear is 0.1g. If you are healthy enough and have no history of heart disease or asthma, you can try a small spoonful-about 5g of pure capsaicin will survive. 5 grams of pure capsaicin is the theoretical limit that the human body can bear, but after you eat this spoonful of pure capsaicin. You won't want to eat anything for hours.
Speed limit: How fast does the leg run without tearing the tendon?
In 2008, Jamaican "Flying Man" Bolt easily won the 100 meter sprint champion in 9.69 seconds at the Beijing Olympic Games, and then won the 200m sprint champion in 19.3 seconds, breaking the world record twice. Since 1968 used the electronic timer, the men's sprint record of 100 meter has been refreshed more than ten times, but the gap between these records is usually only a few tenths of a second, which means that human legs have reached a "limit area" on how fast they can run.
It is believed that the motivation of running depends on the quadriceps femoris tissue of the thigh, which is attached to the knee through the quadriceps tendon. In the late 1970s, Dr. Gideon Ariel discovered through experiments that if a runner runs 100 meters for more than 9.6 seconds, the force required to reach this speed will be large enough to tear the thigh tendon. Therefore, the fastest speed limit of human running is about 43.06 kilometers per hour.
Electric shock limit: How many volts of electric shock can the human body survive?
Doctors can save lives by using cardiac defibrillators, but excessive electric shocks, including lightning strikes, can kill people. In fact, what kills people is not how high the voltage is, but how big the current passes through the human body. Usually, when a milliampere current passes through the human body, it will produce uncomfortable feelings such as tingling; Current above 10 mA will cause paralysis, severe pain, spasm, high blood pressure, dyspnea and other symptoms. If the current through the human body exceeds 200 mA. Will kill people immediately. The magnitude of current is determined by voltage and resistance. The greater the resistance on the surface of human body, the smaller the current passing through human body. Due to wet or dry skin, the surface resistance of human body varies from 1000 ohm to 65438+1000 million ohm. So the lethal voltage is also between 200 volts and 20 thousand volts. Usually, a healthy heart can theoretically withstand an electric shock of 27,000 volts and still have a chance to survive.
Noise limit: How much volume can your eardrum withstand without bursting?
It is found that the maximum volume that human eardrums can bear is 160 dB, because once this number is exceeded, human eardrums may crack. However, because sound is only a kind of pressure wave, there is almost no theoretical upper limit on the size of sound.
When a jet plane takes off at a distance of 50 meters, the sound is as high as 125 decibels. Loud noise may lead to incontinence and even damage to internal organs. At present, the loudest sound recorded in history is 1883, which was made by the eruption of Krakato volcano in Indonesia. At that time, the explosion sound was recorded as high as 180 decibels, even though it was 160 kilometers away. Anyone within 20 kilometers of the volcano will hear an explosion as high as 200 decibels. At this level, pressure waves will directly damage the lungs of these people, causing air to enter human blood vessels, causing fatal consequences.
(Wang Xiaolin is taken from the Knowledge Expo)