When the temperature is low, why does our skin turn purple with cold?

There are abundant capillaries under the skin. In severe frostbite, it is abnormal bleeding of subcutaneous capillaries, which leads to subcutaneous swelling and hypoxia, and the bleeding blood turns dark red, showing that the skin is swollen and purple. In this case, you should seek medical attention in time.

People with normal capillaries will be stimulated by cold air because of the cold climate in winter. After a long time, subcutaneous arterioles will spasm and contract, forming congestion, which will make some tissues lack oxygen and cause tissue cells to be damaged. At first, the damage is a purple-red lump or induration like broad beans or nails, which is red around and blue in the middle. It is very symmetrical from the distal end of the limbs, and it is most common in the back of the hand and the extended side of the fingers, the edge of the foot and the extended side of the toes, lower limbs, face and ears.

Specifically, these parts of the body have pain, itching, hot water or more serious temperature rise.

After being attacked by cold air, the frozen skin will turn pale, and in severe cases, it will appear red, swollen, itchy, numb, blistered and ulcerated. These symptoms will last for 1~2 months, until the weather gets warmer, and some patients will relapse in the previous position when the next winter comes, which is what we often call chilblain.

Traditional Chinese medicine explained that chilblain is caused by naked skin unable to resist the invasion of cold pathogens and slow blood circulation. In addition, it is also related to patients' poor health, lack of cold tolerance, lack of exercise and overwork. Humidity can improve the heat dissipation rate of the body surface, so people with sweaty hands and feet are also prone to frostbite.

Cold weather will stimulate a series of stress regulation, including nerves, heart rate, blood vessels, blood pressure, body fluids, etc. The ecological environment in the body will also change with the changes of the external environment to adapt to various stimuli. Patients with chronic diseases such as hypertension should be more careful, because these patients are likely to have cerebral infarction or cerebral hemorrhage in cold weather.

Experts suggest that colds caused by colds may also lead to viral encephalitis, acute myelitis, Guillain-Barre syndrome and other diseases. Therefore, keeping warm and cold-proof and preventing colds is an important aspect of winter health care. According to research, nearly 20% of the body's heat is emitted from the head, so it is very important to wear a hat to keep out the cold besides adding clothes to deal with cold weather.