How Many Skin Layers Are There in Human Body?

How many layers of skin are there in the human body? Can you give me some details about each... how they work, what they do?

Doctor Answers 1

Skin layers in the body

The skin is divided into the upper part, called the epidermis and the supporting lower infrastructure, called the dermis. The skin is located and connected to the underlying subcutaneous fat.

Within the epidermis, there are five layers. New skin grows from the basal layer, the stratum basale, also called the stratum germinativum (new cells germinate or grow from these cells) which is the lowest layer of the epidermis. Cells located in this layer are round or oval and as they duplicate, the new cells rise up into the stratum spinosum or straum malpighii. As these cells mature and rise further, they become more flat until they loose their nuclei through the stratum granulosum. The cells then die and become very flat and are found in the top, dead layer, called the stratum corneum or the horny layer (horns of animals, human fingernails and calluses are all formed from this keratin protein). There is a clear layer that acts as a cushion to prevent shearing in some areas of the body and is located between the stratum corneum and the stratum granulosum, named the stratum lucidum (lucid for clear).

The dermis under the epidermis, is composed of two layers. These include the more superficial papillary dermis and the deeper reticular dermis.

The epidermis acts as a barrier to environmental trauma and stresses including physical, thermal, ultraviolet and biologic insults. It also serves as an envelope enclosing vital structures. The epidermis contains melanocytes which are pigment cells helping protect against skin cancer from ultraviolet radiation (sun tanning) and immune cells called the Langerhans cells, which help fight against infection.

The dermis helps provide temperature regulation by allowing the sweat glands to secrete their fluid, which uses heat from the skin to evaporate, thereby cooling off the body. It also uses the sensory nerves for pain, temperature and pressure by receiving stimuli from the environment enabling us to avoid injury and help us maintain our coordination during fine movements.

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