Layers of the Peel

The Epidermis

The epidermis is the outermost layer of the pare, and protects the body from the environment. The thickness of the epidermis varies in different types of skin; it is just .05 mm thick on the eyelids, and is i.5 mm thick on the palms and the soles of the feet. The epidermis contains the melanocytes (the cells in which melanoma develops), the Langerhans' cells (involved in the immune system in the pare), Merkel cells and sensory nerves. The epidermis layer itself is made up of five sublayers that work together to continually rebuild the surface of the pare:

The Basal Cell Layer

The basal layer is the innermost layer of the epidermis, and contains small circular cells called basal cells. The basal cells continually divide, and new cells constantly push older ones up toward the surface of the pare, where they are eventually shed. The basal jail cell layer is besides known as the stratum germinativum due to the fact that it is constantly germinating (producing) new cells.

Illustration of the layers of the skin

The basal cell layer contains cells called melanocytes. Melanocytes produce the skin coloring or pigment known as melanin, which gives skin its tan or brown colour and helps protect the deeper layers of the skin from the harmful furnishings of the sunday. Sun exposure causes melanocytes to increase production of melanin in order to protect the skin from damaging ultraviolet rays, producing a suntan. Patches of melanin in the skin cause birthmarks, freckles and age spots. Melanoma develops when melanocytes undergo malignant transformation.

Merkel cells, which are tactile cells of neuroectodermal origin, are besides located in the basal layer of the epidermis.

The Squamous Prison cell Layer

The squamous cell layer is located higher up the basal layer, and is also known as the stratum spinosum or "spiny layer" due to the fact that the cells are held together with spiny projections. Inside this layer are the basal cells that have been pushed upward, withal these maturing cells are at present called squamous cells, or keratinocytes. Keratinocytes produce keratin, a tough, protective protein that makes upwardly the bulk of the structure of the skin, pilus, and nails.

The squamous prison cell layer is the thickest layer of the epidermis, and is involved in the transfer of certain substances in and out of the body. The squamous jail cell layer likewise contains cells called Langerhans cells. These cells attach themselves to antigens that invade damaged skin and alert the allowed system to their presence.

The Stratum Granulosum & the Stratum Lucidum

The keratinocytes from the squamous layer are then pushed upwardly through 2 thin epidermal layers called the stratum granulosum and the stratum lucidum. As these cells move further towards the surface of the skin, they get bigger and flatter and attach together, and then eventually go dehydrated and die. This process results in the cells fusing together into layers of tough, durable cloth, which go on to migrate upwards to the surface of the pare.

The Stratum Corneum

The stratum corneum is the outermost layer of the epidermis, and is fabricated upwards of x to xxx thin layers of continually shedding, expressionless keratinocytes. The stratum corneum is too known equally the "horny layer," considering its cells are toughened like an animate being's horn. As the outermost cells age and wear down, they are replaced by new layers of stiff, long-wearing cells. The stratum corneum is sloughed off continually as new cells accept its place, but this shedding process slows down with age. Consummate jail cell turnover occurs every 28 to 30 days in young adults, while the same procedure takes 45 to fifty days in elderly adults.

The Dermis

The dermis is located beneath the epidermis and is the thickest of the three layers of the skin (i.5 to 4 mm thick), making up approximately xc percentage of the thickness of the pare. The main functions of the dermis are to regulate temperature and to supply the epidermis with nutrient-saturated blood. Much of the body's h2o supply is stored within the dermis. This layer contains well-nigh of the skins' specialized cells and structures, including:

  • Blood Vessels
    The blood vessels supply nutrients and oxygen to the skin and take away cell waste material and jail cell products. The blood vessels also send the vitamin D produced in the skin dorsum to the remainder of the trunk.
  • Lymph Vessels
    The lymph vessels bathe the tissues of the pare with lymph, a milky substance that contains the infection-fighting cells of the immune system. These cells work to destroy whatsoever infection or invading organisms as the lymph circulates to the lymph nodes.
  • Hair Follicles
    The hair follicle is a tube-shaped sheath that surrounds the part of the hair that is under the skin and nourishes the hair.
  • Sweat Glands
    The average person has about three 1000000 sweat glands. Sweat glands are classified according to two types:
    1. Apocrine glands are specialized sweat glands that tin can exist found simply in the armpits and pubic region. These glands secrete a milky sweat that encourages the growth of the bacteria responsible for body odor.
    2. Eccrine glands are the truthful sweat glands. Found over the entire trunk, these glands regulate body temperature by bringing water via the pores to the surface of the pare, where information technology evaporates and reduces peel temperature. These glands can produce upward to two liters of sweat an 60 minutes, however, they secrete mostly h2o, which doesn't encourage the growth of odor-producing leaner.
  • Sebaceous glands
    Sebaceous, or oil, glands, are attached to hair follicles and can be constitute everywhere on the body except for the palms of the easily and the soles of the feet. These glands secrete oil that helps keep the peel smoothen and supple. The oil also helps keep pare waterproof and protects confronting an overgrowth of bacteria and fungi on the skin.
  • Nerve Endings
    The dermis layer also contains hurting and touch receptors that transmit sensations of pain, itch, pressure and information regarding temperature to the brain for estimation. If necessary, shivering (involuntary wrinkle and relaxation of muscles) is triggered, generating body heat.
  • Collagen and Elastin
    The dermis is held together past a protein called collagen, made past fibroblasts. Fibroblasts are peel cells that give the skin its strength and resilience. Collagen is a tough, insoluble protein found throughout the trunk in the connective tissues that agree muscles and organs in identify. In the skin, collagen supports the epidermis, lending information technology its durability. Elastin, a similar protein, is the substance that allows the pare to spring dorsum into place when stretched and keeps the skin flexible.

The dermis layer is fabricated upwards of two sublayers:

The Papillary Layer

The upper, papillary layer, contains a thin organization of collagen fibers. The papillary layer supplies nutrients to select layers of the epidermis and regulates temperature. Both of these functions are achieved with a thin, extensive vascular organization that operates similarly to other vascular systems in the body. Constriction and expansion control the amount of blood that flows through the skin and dictate whether body heat is dispelled when the skin is hot or conserved when it is cold.

The Reticular Layer

The lower, reticular layer, is thicker and made of thick collagen fibers that are bundled in parallel to the surface of the skin. The reticular layer is denser than the papillary dermis, and it strengthens the skin, providing structure and elasticity. It also supports other components of the pare, such as hair follicles, sweat glands, and sebaceous glands.

The Subcutis

The subcutis is the innermost layer of the skin, and consists of a network of fat and collagen cells. The subcutis is also known every bit the hypodermis or subcutaneous layer, and functions as both an insulator, conserving the trunk'south heat, and as a shock-absorber, protecting the inner organs. It also stores fat equally an energy reserve for the body. The blood vessels, nerves, lymph vessels, and hair follicles also cantankerous through this layer. The thickness of the subcutis layer varies throughout the body and from person to person.