There is something that always accompanies us when we run around with our friends, when we lie and feel guilty about it, when we take a bite out of a hot pepper, or when we have a bad cold with fever. It is sweat. We, humans, sweat in many different occasions throughout our lives. Particularly, we have big and small battles against sweat every day in hot summer. Many people regard sweat as something like an unwelcome guest that visits them in summer, or like some dirty and smelly waste.
However, what will happen if we don’t sweat? We might have to walk around, panting with our tongues sticking out of our mouths like dogs under the scorching sun. Sweat is an essential element for our body, for it plays various roles in our body. Now, let’s start a fun journey with our sweat.
What is sweat?
Sweat is a liquid secreted from sweat glands which are spread all over the skin of the body, which is made up of 99% water and the rest of ions such as sodium, chloride, and potassium. Sodium and chloride control the moisture in the body, and potassium helps metabolism, and calcium and magnesium play an important role in maintaining muscle movement.
One of the reasons why excessive workout can cause cramps is the loss of ions caused by sweating. When we sweat a lot, we lose ions that are important for controlling the movement of muscles or nerves, which causes a problem in normal muscle movement. A research shows that a loss of about 4 kg [8.8 lb] of sweat can cause the body to lose about 5 to 7 percent of sodium and chloride, resulting in muscle cramps.
It is said that the amount of sweat a person sheds in a day is approximately 500 to 700 milliliters on average although it depends on season and the amount of the body movement. The amount of sweat that a person can shed while being conscious is up to 10 liters [2.6 gallons]. It is a tremendous amount of sweat when considering that the amount of sweat a professional soccer player sheds during a match is 4 liters [1.05 gallons] and the amount of sweat a marathoner sweats while completing a course is 6 liters [1.58 gallons].
In our body, there are two types of sweat glands: eccrine glands and apocrine glands. Eccrine glands, which look like balls of yarn, are located on the border between the deeper part of the dermis and the hypodermis. They control the body temperature and are controlled by the sympathetic nerve. About 2 million to 5 million of them are all over the body, and most sweat that is shed is secreted from these glands. The apocrine glands are the main factor of smell. It varies by individuals, but they mainly excrete sweat containing protein, lipid, sugar, pyruvic acid, etc. As the skin germs break these down into fatty acids and ammonia, odor is created.
Sweat with versatile talents
Just as we don’t feel the importance of the air because it is all around us at all times, we do not realize how many types of work our sweat is doing although we sweat all the time. The major function of the sweat is lowering the body temperature. When we are exposed to wind while our skin is wet, our body feels cold and shivers. This is because the water takes heat from the skin as it evaporates. The efficient cooling system of the body works on the same principle. Sweat is just like coolant; when it is emitted from the sweat glands, it cools the body heat down once, and when it evaporates from the skin, it cools the body heat down once more.
The effect of the sweat’s control of the body temperature is significant, that 80% of the heat emission is done by the sweat. If a person who weighs 60 kg [132 lb] sheds 1 liter [0.26 gallon] of sweat, he or she can reduce the body temperature by about 10℃ [18℉]. Thanks to the sweat-the highly efficient air conditioner, we can always maintain the body temperature at 36.5℃ [97.7℉] no matter how hot it is and no matter how violently we exercise.
Sweat sometimes plays the role of a mirror reflecting the mental state. You’ve probably experienced moments when your hands got wet with sweat while waiting for an important interview or confessing your love or watching your favorite baseball team hit a home run and put a comeback on the other team. It is because the sympathetic nerve secretes sweat when we feel stressed out, nervous, anxious, shy, or taken aback. This emotional sweating in response to emotive stimuli is most evident on the face, armpits, palms, and soles. Sweat shed at such times relaxes tension and reduces stress.
Emotional sweating is used in modern forensic medicine and psychiatry. As emotional sweating occurs unexpectedly without an incubation period due to emotional changes and the electrical conductivity rises as the sweat gets the hands and feet wet, it is used for a lie detector or for measuring the level of mental stress.
Sweating does not only occur by high temperatures or emotional stimuli, but also by stimuli such as sour or spicy taste, on the forehead, nose, or upper lip. This happens as the sweat glands on the face are stimulated by the neural reflex linked to taste.
Also, the value of sweat cannot be ignored even in aspect of discharging waste. Sweat glands belong to the excretory system along with the kidneys. When sweat is secreted from sweat glands, it pushes out body wastes out of the body and helps maintain the status of the inside of the body. Particularly, the sweat shed while exercising makes waste and heavy metals such as lead and cadmium come out of the body, benefiting the health. However, sweating an excessive amount could rather harm the health as it makes the body lose not only the waste and heavy metals, but also minerals that are essential for the body such as iron, magnesium, manganese, and zinc.
Signal for the health of our body
The adequate amount of sweat is a proof that our body is controlling the body temperature well, but excessive sweating or a lack of sweating could be signs that something is wrong with our body. In such cases, it is important to find out what causes excessiveness or lack of sweating.
Hyperhidrosis, which is excessive sweating, is caused by abnormally elevated function of the sympathetic nerve. For this, people feel uncomfortable to shake someone’s hand as their hands easily get wet with sweat or feel embarrassed as the clothes around their armpits are soaking wet. In severe cases, people are impacted in their social lifestyles.
Excessive sweating is a problem, but not sweating at all is a bigger problem. Anhidrosis is the inability to sweat, which makes it impossible for the body to cool itself. Patients with this condition have to struggle with heat. It can lead to hyperpyrexial insolation, heatstroke, or even to death. The elderly, sometimes, do not realize that their bodies have overheated until they collapse with heatstroke because their abilities to sweat are weaker.
Recently, a sensor has been invented to be attached to the skin, in order to analyze the sweat and explain the status of the health. Sweat contains various chemical matters that show one’s health, and various matters that serve as an index of stress. For example, diabetes can be detected by the level of glucose contained in the sweat, and cystic fibrosis by the level of chloride ion in the sweat. Dehydration can be checked by measuring the pH level of sweat, and one’s response to stress can be observed by the changes of cortisol which is excreted in response to stress. Much research is expected to be done about sweat as a means to convey the information about the body.
Sweat maintains the body temperature, discharges body waste, and eases tension according to the changes made in the body. With these many functions, sweat protects our body. Sweat is an important barometer that shows the health of the body and the mind.
“No sweat, no sweet.”
Just like the expression, “Those who don’t sweat cannot taste the sweetness of victory,” sweat is also a symbol of an inevitable process, effort, and patience to bear fruit. The sweat a farmer sheds while working hard, the sweat an athlete sheds while practicing for the Olympics, the sweat a student sheds while studying in the heat, etc. The term sweat is used to describe a person’s attitude toward their lives. Like this, sweat contains one’s efforts along with its functions to maintain health. Everything that you do, shedding sweat, has as much noble value as the sweat you shed.
- Reference
- Park, Tae-jin. 여름의 불청객이라고? ‘땀’의 항변 [Un Unwelcome Guest of Summer? Sweat’s Protest]. Korea: KISTI’s Science Scent, No. 1,663.
- Ahn Se-yeong and Jo Jeong-rae. 2016. 다한증의 이해와 치료 [Understanding and Treatment of Hyperhidrosis]. Korea: Y-Gelli Books.