Skin Anatomy

The skin is the largest organ in the human body. It consists of two layers:

• The Epidermis
• The Dermis

The Epidermis

The outer layer of the epidermis is the stratum corneum, a protective layer which consists of 15 to 40 layers of flattened skin cells or corneocytes that migrate up from the bottom layer of the epidermis.

The epidermis replaces itself about once a month. The stratum corneum serves as a barrier to protect the human body from external environmental factors.

Beneath the stratum corneum lie the keratinocytes, cells which form the building blocks of the epidermis. At the lowest level of the epidermis there is a row of cells called the basal cell layer. This layer contains basal cells which regenerate the major portion of the epidermis, as well as melanocytes, which produce the pigment melanin. Skin color is determined by the amount of melanin in the skin.

Also present are sensory nerve receptors and cells which are part of the immune system. The epidermis is the layer where most skin cancers arise.

The Dermis

The dermis consists of collagen and elastic fibers within a ground substance or matrix. Within the dermis are:

• Hair Follicles.
• Sebaceous glands or Oil Glands lubricate the skin and are connected to the hair follicles. This is the site where acne arises. Acne lesions develop when excessive oil is trapped providing a medium for acne bacteria to grow.
• Apocrine glands or Scent Glands release chemicals which may play a vital role in sexual attraction. These are also are connected to the hair follicles.
• Eccrine glands or Sweat glands which produce perspiration to control the body temperature.
• Nerve endings, which register sensations to touch, temperature, pain and pressure.
• Capillaries which carry oxygen and nutrients to the skin.
• Underneath the Skin is the adipose tissue or fat layer.