The Skin is much larger than most people think
When people ask about the Largest Organ in the human body, many respond with either the brain or the heart. Both of those organs are very important to the way that humans operate. However, neither One is larger in terms of mass or surface area than another organ that is commonly overlooked in favor of the others: your Skin.
Your Skin: a multi-layered protective layer
People may view the Skin as simply being an external covering. This is understandable since it is easier to visualize internal organs such as the brain and heart. However, as defined by merriam webster, an organ is a group of tissues working together to achieve a certain function. Therefore, the Skin fits the description of an organ. It has multiple layers and cell types. It is a living tissue that is always regenerating itself.
Comparing size and mass
On average, the human Skin is estimated to be about 1.5 to 2.0 square meters (16 to 22 square feet) in size. To help illustrate how big this really is, imagine placing a twin-sized bed sheet on top of a person. The Skin accounts for about 15% of an individual’s total body weight. For example, if you were to calculate the percentage of your body weight based upon a body weight of 150 pounds, your Skin would account for approximately 22.5 pounds. As previously mentioned, there are some organs that are quite large internally (like the liver), however none are larger than the Skin. The liver is generally about 3 to 3.5 pounds. Additionally, the brain is generally less than 3 pounds.
Components of the Skin
Unlike an internal organ where there may be only a few basic components, the Skin is made up of multiple layers. Each layer serves a different purpose in order to protect the body. These layers work together to create a robust barrier.
Outermost layer: epidermis
The epidermis is the outermost layer of the Skin. It is relatively thin. This layer is primarily made of keratinocytes. Keratinocytes are cells that make keratin, a type of protein that provides Skin strength and helps to repel water. New keratinocyte cells are continually created, with older keratinocyte cells continually dying off. Every 28-30 days, you essentially receive a new epidermis. melanin, which creates Skin color and helps protect against damage caused by UV rays, is produced in the epidermis by special cells known as melanocytes.
Middle layer: Dermis
Located below the epidermis is the Dermis. This is a thicker layer filled with blood vessels, nerves, hair follicles and glands associated with sweat and oils. The Dermis receives oxygenated blood from capillaries in the bloodstream and delivers oxygen to the epidermis via diffusion. Nerve endings in the Dermis enable feelings of touch, pressure, pain and temperature to be felt. Collagen and elastin are two types of proteins found in the Dermis that give Skin its strength and flexibility.
Innermost layer: Hypodermis (subcutaneous tissue)
At the bottom layer is Hypodermis or subcutaneous tissue. Subcutaneous tissue is primarily composed of fat and connective tissue. The primary function of subcutaneous tissue is to act as insulation and cushioning for internal organs. Subcutaneous tissue allows for thermal regulation and energy storage (fat).
Skin functions beyond being a physical barrier
In addition to shielding us from the elements, our Skin accomplishes numerous other critical functions to sustain life and maintain good health.
Protective function
One of its most important roles is functioning as a barrier against potential harm from external substances including dirt, germs, toxic chemicals and minor physical trauma. If we didn’t have this barrier our bodies would be susceptible to myriad dangers.
Thermal regulation
Another extremely important function that Skin serves is temperature regulation, or thermoregulation. When we become overheated our dermal blood vessels expand and increase circulation to cool down through evaporation of sweat. Conversely, when we’re cold our dermal blood vessels constrict to retain heat within our bodies. Tiny muscle attachments near each hair follicle contract creating goose bumps. Goosebumps help to reduce heat loss by trapping additional layers of insulating air next to our Skin.
Sensory function
Our Skin is perhaps One of the biggest sensory organs in the human body. millions of nerve endings exist throughout our Skin allowing us to feel touch, pressure, vibration, heat, cold, and pain. Sensory input from our Skin is vital for interacting with our environment safely and accurately. Try to comprehend navigating the world without feeling warmth from a fire or experiencing a sharp edge.
Synthesis of Vitamin d
Vitamin d synthesis is an important yet lesser-known function performed by our Skin. ultraviolet b (UV-b) light from sunlight causes a compound present in Skin called previtamin d3 to convert into Vitamin d. Vitamin d is needed for calcium absorption, bone development and a healthy immune system. Although too much sun exposure can be detrimental to health, moderate sun exposure is required for obtaining adequate levels of Vitamin d.
Waste removal through perspiration
Although the kidneys are the primary organs for removal of waste products from our bodies, our Skin also removes waste products from our bodies through sweating. Water and salt are released along with trace amounts of urea and ammonia.
Other candidates for “largest organ”
There are several other candidates for “largest organ”, although none of them meet criteria for surface area or weight as set forth above.
Gastrointestinal tract: lengthy system comprised of multiple organs
The gastrointestinal (GI) tract (or digestive tract) is a lengthy tube measuring approximately 9 meters (30 feet) long when uncoiled. While it does contain a large amount of surface area due to numerous creases and finger-like projections known as villi located on its lining, the surface area contained within the GI tract does not approach the surface area contained within the Skin. In reality, the GI tract represents a system consisting of several organs (mouth, esophagus, stomach, small intestine and colon), whereas the Skin represents a single organ.
Liver: internally largest solid organ
As stated above, the liver is usually considered to be the largest solid organ inside humans. The liver performs over 500 various physiological functions, including detoxifying harmful substances ingested through food and drink, synthesizing proteins necessary for clotting of blood, etc. However, its size does not approach the size of the Skin.
Caring for your largest organ
Since its functions are so critical to maintaining health, it’s no surprise that taking care of your Skin is important. Protecting your Skin from excessive exposure to direct sunlight, practicing good personal hygiene habits, treating any Skin problems quickly will assist greatly in maintaining your overall health.
Doctors who specialize in the diagnosis, treatment and prevention of diseases related to Skin are called dermatologists. Many times dermatologists stress how Skin can be used as an indicator of disease elsewhere in the body.
Conclusion:
Next time someone asks you what is the Largest Organ in humans you’ll know that it’s not something buried somewhere under layers of muscle or other tissue — it’s something that covers you from head-to-toe — your Skin!
Frequently asked questions regarding human body’s largest organ
Sources
- Skin 101: What it is and how to care for it — American Academy of Dermatology
- Anatomy, Skin (Integument) — National Center for Biotechnology Information (NCBI)
- The Largest Organ: Skin — BioDigital Human
- Skin Conditions — MedlinePlus
- Skin – Human Anatomy — Britannica
