Layers of the Skin

albinism

genetic disorder that leads to a lack of melanin production in the skin, hair, and eyes

basal cell

type of stem cell found in the stratum basale and in the hair matrix that continually undergoes cell division, producing the keratinocytes of the epidermis

collagen fibers

provide structure and tensile strength to the dermis, with strands of collagen extending into both the papillary layer and the hypodermis

dermal papilla

(plural = dermal papillae) extension of the papillary layer of the dermis that increases surface contact between the epidermis and dermis

dermis

layer of skin between the epidermis and hypodermis, composed mainly of dense, irregular connective tissue and containing blood vessels, hair follicles, sweat glands, and other structures

elastin fibers

fibers made of the protein elastin that increase the elasticity of the dermis

epidermis

outermost tissue layer of the skin

hypodermis

connective tissue connecting the integument to the underlying bone and muscle; it contains loose areolar connective tissue and a high concentration of adipose tissue

integumentary system

skin and its accessory structures (e.g., hair, nails, and glands)

keratin

type of structural protein that gives skin, hair, and nails their hard, water-resistant properties; areas with high amounts of keratin (e.g. the stratum corneum, hair shaft, and nail body) contain only dead cells, as the keratin causes cell death

keratinocyte

cell that produces keratin and is the most predominant type of cell found in the epidermis

Langerhans cell

specialized cell found in the stratum spinosum that functions as a macrophage; in other words, it removes foreign invaders, such as bacteria

Meissner corpuscle

(also, tactile corpuscle) receptor in the papillary dermis of the skin that responds to the sense of touch

melanin

pigment that determines the color of hair and skin

melanocyte

cell found in the stratum basale of the epidermis that produces the pigment melanin

Merkel cell

receptor cell in the stratum basale of the epidermis that responds to the sense of touch

papillary layer

thin, superficial layer of the dermis that extends into the stratum basale of the epidermis forming papillae, or folds

reticular layer

deeper and by far thickest layer of the dermis; it has a reticulated (web-like) appearance due to the presence of abundant collagen and elastin fibers

stratum basale

deepest layer of the epidermis, made of epidermal stem cells; it is a single layer thick and is the source of most cell division (i.e. mitosis)

stratum corneum

most superficial layer of the epidermis; composed only of dead cells

stratum granulosum

layer of the epidermis superficial to the stratum spinosum; it has a granular appearance

stratum lucidum

layer of the epidermis between the stratum granulosum and stratum corneum, found only in thick skin covering the palms, soles of the feet, and digits; it has a clear appearance

stratum spinosum

layer of the epidermis superficial to the stratum basale, characterized by the presence of desmosomes and Langerhans cells; it is composed of spiny-shaped cells

vitiligo

skin condition in which melanocytes in certain areas lose the ability to produce melanin, possibly due an autoimmune reaction that leads to loss of color in patches