Skin is the largest and heaviest organ of the body. It consists of three main layers; the epidermis, dermis, and hypodermis. Skin can either be thin or thick. The main difference is the thickness of the epidermis and dermis, which are the top two layers of skin.
Thin skin covers most of the body and can vary in thinness, with the thinnest skin covering the eyelids. Thick skin is present on the soles of the feet and palms of the hands.
In addition to differing thicknesses, the skin also differs in what is present in the layers. For example, thick skin has no hair follicles or sebaceous glands, whereas thin skin does.
In this article, we look at the differences in appearance, structure, and function of thin and thick skin.
Thin skin covers most of the body, except on the soles of the feet and palms of the hands, and contains fewer cellular layers than thick skin.
The epidermis of thin skin ranges from 0.07–0.15 millimeters (mm). Thin skin can vary in thickness in different parts of the body and is particularly thin across the eyelids. Thin skin is
Thin skin also contains hair follicles, sweat glands, and sebaceous glands.
Thick skin is present on the soles of the feet and palms of the hands. This is because these areas receive more friction than other areas of the body, and thicker skin helps to protect from potential damage.
The epidermis of thick skin can be up to 1.5 mm. Thick skin does not contain any hair follicles or sebaceous glands. Thick skin also contains no arrector pili muscles, which cause goosebumps.
Thick skin is thicker due to it containing an extra layer in the epidermis, called the stratum lucidum. Thick skin actually has a thinner dermis layer than thin skin, but is still thicker due to the stratum lucidum layer present in the epidermis.
The stratum basale, also known as the stratum germinativum, is the deepest layer of the epidermis. It is the layer just above the dermis.
This layer continuously produces new skin cells. It also contains melanocytes, which are cells that produce skin pigment and help protect the skin from sun damage.
The stratum spinosum consists of eight to ten layers of cells. People may refer to the stratum spinosum as the prickle cell layer because of the irregular structure of cells, which look like spines or prickles.
The stratum granulosum consists of three to five layers of cells. The stratum granulosum contains granules, which are rich in lipids.
Only thick skin contains the stratum lucidum layer. The stratum lucidum is a thin, transparent layer consisting of two to three layers of cells. It contains a protein called eleidin.
The stratum corneum is the upper layer of the epidermis. It consists of 20–30 layers of cells. It contains keratin and horny scales, which make it tougher and able to thicken into calluses.
The stratum corneum contains dead keratinocytes, which produce defensins. Defensins are strings of amino acids that protect the body from infection.
Connecting the dermis and epidermis are structures called dermal papillae. Dermal papillae are more prominent in thick skin than thin skin.
Dermal papillae increase the surface area between the epidermis and dermis, allowing for more oxygen, food, and waste to pass between the layers.
The following table summarizes the key structural differences between thin and thick skin:
|Structures||Thin skin||Thick skin|
|Dermis||Thicker dermis, can vary depending on area of body||Thinner dermis|
|Epidermis||Thinner epidermis, ranging from 0.07–0.15 mm. Epidermis contains 4 layers.||Thicker epidermis, ranging from 0.8–1.5 mm. Epidermis contains 5 layers.|
|Sweat glands||Contains eccrine sweat glands, and apocrine sweat glands in the armpits and groin||No apocrine sweat glands. Only eccrine sweat glands are present in thick skin.|
|Dermal papillae||Present||More prominent|
|Sebaceous glands||Contains sebaceous glands||No sebaceous glands|
|Hair follicles||Contains hair follicles||No hair follicles|
|Stratum lucidum||No stratum lucidum layer||Stratum lucidum layer in the epidermis|
|Stratum corneum||Thin stratum corneum layer||Thick stratum corneum layer|
|Stratum granulosum||Single layer of cells||4–5 cells thick|
|Stratum spinosum and basale layer||Stratum spinosum is thinner||Both layers are more prominent|
Skin in general has many different functions, such as protection, sensation, and thermoregulation. Both thin and thick skin have properties that allow the skin to function correctly.
For example, thin skin contains hair follicles, which are
In addition, thin skin contains sebaceous glands, which produce sebum. Sebum
Thin skin also contains eccrine and apocrine sweat glands. Sweat glands help to regulate body temperature by releasing sweat to cool the body, and also
Thick skin provides protection from damage in areas that experience more friction and abrasion, such as the palms of the hands and the soles of the feet. Thick skin also contains eccrine sweat glands to help regulate body temperature.
Skin is a large, complex organ with a wide range of vital roles. Thin skin and thick skin have different structures and functions in the body. The layers they contain provide their thickness and allow them to carry out their roles.
Thin skin is present on most of the body, and helps to protect against infections, regulate temperature, and allows hair to grow. Thick skin covers the palms of the hands and the soles of the feet and protects these areas from extra abrasion and friction.