The Role of the Integumentary System in Thermoregulation : How Skin Helps Maintain Body Temperature

The integumentary system is the largest organ system in the body. Comprising of your skin, hair, nails, and glands, the integumentary system forms the first line of defense of the body, keeping it safe not only from disease-causing pathogens but also from environmental factors like ultraviolet rays and pollution. The system forms a physical barrier between your external environment and the internal environment of the body. The integumentary system also plays many other important roles in the body, including regulating the temperature of the body, meaning keeping the temperature of the body under control. Read on to find out the role of the integumentary system in thermoregulation.

The process of thermoregulation is an important one in the human body. It is the process by which the body maintains its temperature, preventing it from becoming too hot or cold. There are many parts of the body that are involved in the process of thermoregulation, but the most important and indispensable role in thermoregulation is played by the skin, which is the largest organ of our body and the integumentary system.^(1, 2, 3)

The integumentary system helps keep the body temperature under control even when the environmental temperature continues to change. The skin plays an important role in the process of thermoregulation, allowing the body to maintain its core internal temperature no matter what the external environment is.⁽⁴⁾

One of the most important aspects of the integumentary system in this is homeostasis, which is the dynamic state of stability achieved between the human body’s internal and external environment. The skin plays a critical role in homeostasis, working to keep different parts of the body at a constant temperature. The skin carries out this work by reacting differently to the different hot and cold conditions in order to ensure that the temperature of your inner body remains constant.^(5, 6) Let’s take a closer look at how this happens.

The skin is the largest organ of the body. An integral part of the integumentary system, the skin is the first barrier to the environment and carries out the critical function of protecting our internal organs. Due to its huge surface area on the body, the skin has a crucial role to play in the process of thermoregulation. The entire process of skin-based thermoregulation that takes place, occurs through numerous means.

1. Thermoregulation and Vasodilation

   The first way this happens is due to the abundance of blood vessels that can be found in the second layer of the skin known as the dermis. The body needs to be cooled down, and the body vasodilates or expands these blood vessels.⁽⁷⁾

   The process of vasodilation involves the expansion of the size of the blood vessels. These enlarged peripheral blood vessels of the skin make it possible for larger amounts of blood to flow toward the surface of the skin. This makes it possible for the body to let go or release a lot of the body heat through radiation. Radiation, when it comes to thermoregulation, actually refers to thermal radiation. Thermal radiation is the process of transferring heat through space by means of electromagnetic waves.⁽⁸⁾

   At the same time, if there is any fluid such as circulating water or air in a pool and it touches the pool while the body is still very hot, this allows immediate heat loss to take place through a process known as convection. It is important to know that the higher the amount of the body’s surface area that is exposed to this circulating air or water (meaning there is very little clothing on the body), the higher will be the speed of the circulating air and the smaller will be the distance between the surface of your skin and the blood vessels. This means that a greater amount of heat will be lost through convection.

   Similarly, if the skin comes in contact with a cold object when the body loses heat through the process of conduction, Conduction is the process in which direct transfer of heat takes place from a hotter surface to a colder surface that is touching that hot surface.

2. Thermoregulation and Perspiration

   Another process through which the integumentary system carries out thermoregulation is through the natural process of sweating or perspiration. We begin to perspire or sweat when the body temperature goes above roughly 37 degrees Celsius (98.6 degrees Fahrenheit). Production of sweat is increased or decreased as required by the integumentary system. As the drops of sweat begin to appear on and eventually evaporate from the skin’s surface, they carry the body heat away with them. It is not incorrect to say that the greater the surface area of the skin and the higher the rate of perspiration, the greater will be the rate of cooling through sweating. In cases of high humidity, though, it will restrict the body’s ability to dissipate the heat through the process of perspiration.^{(9, 10, 11)}

3. Thermoregulation and Vasoconstriction

   The hairs on the skin also play a role in the process of thermoregulation. Generally, the hairs on the skin lie completely flat against the skin. This prevents heat from getting trapped by the layer of air that lies still between these hairs. This is due to the tiny muscles located underneath the surface of the skin known as arrector pili muscles. When these arrector pili muscles are relaxed, the hair follicles attached to them are not erect. The flat hairs on the skin increase the flow of air against and next to the skin and also increases heat loss by the process of convection. However, when the hairs are standing up (when you experience goosebumps for example), the air gets trapped between this layer of hair to reduce the heat loss.⁽¹²⁾

   If the body wants to prevent the loss of excess heat, especially on a cold day, the integumentary system will act quickly to constrict the blood vessels on the skin. This process is referred to as vasoconstriction. Since the blood vessels are constricted, they become narrower than they were before. This ensures that there is lesser blood flowing through the skin, thus letting less heat to escape into the atmosphere through convection, radiation, or conduction. The body also restricts or stops the process of perspiration to reduce any type of evaporative heat loss as well.^(13, 14)

   The integumentary also thermoregulate by using hair. The arrector pili muscles contract in a process known as piloerection. This lifts up the hair follicles, making them stand upright, which makes the hairs stand up or on end. This acts as an insulating layer, which traps heat. This is also the way in which goosebumps form since human beings do not have that much hair on the skin and the contracted muscles can be easily seen.

   Since humans have too little or sometimes no body hair as compared to other mammals and birds, this hair-based process of thermoregulation is not as effective. Though this is not technically a mechanism for thermoregulation, the fat associated with the skin does play a role in insulating the body and increasing the body temperature.⁽¹⁵⁾

The integumentary system is a complex organ system in the body that is vitally important for carrying out many functions. Apart from forming the first line of defense to keep our bodies safe, the integumentary system also plays an important role in regulating the body’s temperature. The integumentary system maintains the body temperature within limits, regardless of what the environmental temperature is. This is done through the process of thermoregulation, and the skin has an important role to play in this procedure. The vast supply of blood vessels in the skin helps regulate your body temperature, while also assisting in homeostasis. By taking good care of our skin, we can ensure that our body remains in good health and continues to function as it should.

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