One person cheers for the graduate school entrance examinationtext|Zhang Ping.
Edit|Arvin.
The cold snap in the north hit one after another, and sitting in the house looking at the snow outside the window, I couldn't help but shiver a few times, I couldn't help shivering, I couldn't help it, but can I control it?Today I will share with you a few "cold" knowledge.
What's going on with shivering on a cold day?Can it be controlled?When it's cold, why do people shiver?
It is to protect against the cold.
Can the trembling be controlled?
No, shivering is a nervous response that generally cannot be controlled.
A person's body temperature is generally maintained at 36-375, when ** is exposed to the outside temperature, the perceived temperature will be directly conducted to the control center.
When the weather is hot, the control center will innervate the sympathetic nervous system to excite, so that the pores and sweat pores open to dissipate heat and sweat to reduce body temperature.When people are at rest, they mainly rely on the basal metabolism of internal organs to maintain body temperature.When the weather is cold, the sympathetic nerves cause the muscles in all parts of the limbs, including the muscles near the teeth, to shiver, causing the muscles and fat cells to tighten and generate heat to replenish the body.
The liver is the main heat-producing organ in the internal organs.
When the cold is severe, the muscle fibers spontaneously contract synchronously, which is known as shivering – commonly known as shivering. Shiver produces a considerable amount of heat in a short period of time, and its heat production is equivalent to 5 times that of basal metabolism. This is the reason why people shiver when it's cold, and shivering is the body's instinctive response to resist the cold.
Can cold sensations be contagious?Yawning is contagious, that feeling of cold is contagious?
OK. Researchers in the UK have conducted an in-depth study on this issue. They selected 36 volunteers and asked them to **several paragraphs**, and in the first 40 seconds of each paragraph**, a male actor continuously added hot water or ice cubes to a transparent container that was originally filled with water, and then reached into the container.
At the same time, the researchers measured the temperature of the volunteers' hands with instruments. The results showed that when the actor was seen putting his hand into the ice water, the temperature of the volunteer's hand decreased and his left hand decreased by 02. The right hand is lowered by 005℃。
The results of this study were published in the American "Science Public Library Composite Volume", which was analyzed by the researchersThe reason for this phenomenon may lie in a group of nerve cells in the brain called "mirror neurons" that help people better understand others.
Which is colder, dry cold or wet cold?Which is colder, dry cold in the north or wet cold in the south?
At the same temperature, the little ones in the south are colder.
Every winter, netizens will see this paragraph:
The dry cold in the north is a physical attack, which can be easily defended against by wearing more clothes;
The clammy cold in the south is a magical attack, and no amount of clothing is useless.
So, which is colder, dry cold or wet cold?
Literally, the main difference between the two is the humidity. This actually involves the concept of "body temperature".
The temperature in the weather forecast only represents the degree of cold and warm air, and cannot fully represent the human body's perception of the environment. Under the same temperature conditions, people may have different feelings of cold and warm due to the constant changes in humidity, wind speed, light and other factors.
So, what is the effect of humidity on the perceived temperature?In general, when the temperature is high, the higher the humidity, the hotter we feel;And when the temperature is lower, the higher the humidity, the colder we feel.
Therefore, if the temperature in the south and north is the same, under normal circumstances, the friends in the south will feel colder.
But most of the time,In winter, the temperature in the south is much higher than in the north, so that sometimes there are mink wrapped in the north and the waist is still bare in the south.
Why don't your eyes feel cold?Why do you never feel too cold in your eyes?
Because the eye does not have a temperature sensor.
In cold weather, our faces will freeze and our noses will freeze red. However, our eyes seem to be safe and sound, and we never feel cold. Why is that?
Physiologists believe that there are many temperature "sensors" that can sense cold and heat, also known as "cold spots" or "hot spots", are distributed on the surface and internal organs of the human body.
When the outside temperature drops, the temperature also drops, which stimulates the cryoreceptors of the epidermis, which in turn "report" to the temperature sensory center of the cerebral cortex through the nervous system, so that the person feels cold.
The structure of the eyeball is relatively unique, and there are no temperature sensors on the cornea, conjunctiva, and sclera, so it basically does not feel cold.
What's more, the cornea and sclera are transparent tissues that lack blood vessels, which have little heat dissipation effect, and play a role in buffering cold conduction into the eyeballs, plus there is a layer of blood vessels-rich eyelids like two doors of protection, and at the same time, the eyelids continue to open and close, and the eyeballs continue to rotate, generating rich heat, so the eyeballs are not afraid of cold even if they are exposed.