The skin is the largest organ in the body, correspondingly, it plays very significant roles when it comes to health and overall well being. The skin serves many purposes. However, most people take the skin for granted and do not appreciate the importance not until they suffer from injury, various diseases and bad conditions. Outmost care of this organ is very essential.

To better take care of the skin, it is salient to understand the different structures and functions of each. Not all people know that the skin is made up of different parts. In fact, the skin is divided into three main layers, namely: the epidermis, dermis and hypodermis.

The epidermis and dermis are commonly confused, but the two are completely different structures of the skin that plays different distinct functions in the body. The following paragraphs are in depth discussions to further understand these two layers of the skin.

Epidermis

This is the outermost layer of the skin.  It is approximately 0.05 – 1.5 mm thick. Several cells make up the epidermis. The keratinocytes are by far the most abundant type of cell in this layer. Then there are the melanocytes, which are produced by the corns of the color, substance melanin that gives tone to the skin. The Langerhan’s cells are also found in this layer, these cells interact with the white blood cells and serves as the immune defense.

Layers of the Epidermis (from deepest to most superficial layer)

1. Stratum basale (Stratum germinativum)

This is the deepest layer of the skin where mitosis occurs. This is the process where cells divide leading to formation of new epidermal skin cells. After mitotic division, these cells undergo keratinisation – progressive cell maturation, and migrate to the surface of the skin.

2. Stratum spinosum

The cells that generate from the Stratum basale soon accumulate in this layer through demosomes –structures that join adjacent cells together.

3. Stratum granulosum

As cells progressively mature and undergo keratinisation they accumulate in this layer and gather dense basophilic keratohyalin granules (these are granules found in the cells of keratinizing epithelia).

4. Stratum lucidum

This layer varies throughout the body depending on the frictional forces. The thickest Stratum lucidum are found on the palms of the hands and soles of the feet.

5. Stratum corneum

This is the outermost layer of the epidermis and primarily consists of dying and dead skin cells filled with mature keratin. These cells underwent substance change and break down complex chemicals within the cells that eventually causes their death.

Dermis

The dermis is the middle layer of the skin. It is about 0.3 – 3.0 mm. This basically consists of connective tissues. The essential components of this layer are firmer protein collagen and the fibers of the elastic protein. In addition, this layer contains all types of immune cells and factors that protect the skin.

Layers of the Dermis

1. Papillary Dermis

This dermis layer consists of areolar connective tissue, ridges that extend into the epidermis and dermal papillae that increase the surface area of this layer.

Note: The ridges are responsible for the fingerprints on objects when touched.

2. Reticular Dermis

This layer consists of dense connective tissue that contains interlacing bundles of coarse elastic fibers and collagen. Small quantities of hair follicles, nerves, adipose tissue oil glands and sweat gland ducts reside in between the fibers.

Epidermis vs. Dermis

Note: The epidermis and the dermis are separated by the dermo-epidermal junction. This junction holds the two layers together through the help of fibers, collagen and desmosomes. This is so elastic that it prevents the two layers from separating from leach other due to the high shearing stress.

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