a keratinized stratified squamous epithelium consisting of four distinct cell types and four or five distinct layers.
deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers.
several layers of keratinocytes joined by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin.
one of the five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellar granules (release lipids) and keratohyaline granules.
present only in thick skin. A very thin transparent band of flattened, dead keratinocytes with indistinct boundaries.
most superficial layer; 20-30 layers of dead cells, essentially flat membranous sacs filled with keratin. Glycolipids in extracellular space.
a fibrous protein that gives the epidermis its durability and protective capabilities.
(keratin cells) the most abundant epidermal cells, their main function is to produce keratin fibrils. Tightly connected to each other by desmosomes.
spidery black cells that produce the brown-to-black pigment called melanin.
the pigment produced in a specialized group of cells known as melanocytes that gives human skin, hair, and eyes their color.
aka dendritic cells; play a role in immunity by performing phagocytosis.
aka tactile cells; occasional spiky hemispheres that, in combination with sensory nerve endings, form sensitive touch receptors located at the epidermal-dermal junction
the dense irregular connective tissue that consists of two principal regions: the papillary and the reticular.
the more superficial dermal region composed of areolar connective tissue. It is very uneven and has fingerlike projections from its superior surface, the dermal papillae, which attach it to the epidermis above.
projections that lie on top of the larger dermal ridges. In the palms of the hands and soles of the feet, they produce the fingerprints.
aka tactile corpuscle; are a type of mechanoreceptor. They are a type of nerve ending in the skin that is responsible for sensitivity to light touch. They are most concentrated in thick hairless skin, especially at the finger pads.
small blood vessel in the dermal papillae
the deepest skin layer. It is composed of dense irregular connective tissue and contains many arteries and veins, sweat and sebaceous glands, and pressure receptors.
aka lamellar corpuscle; are one of the four major types of mechanoreceptor. They are nerve endings in the skin responsible for sensitivity to vibration and pressure.
aka superficial fascia; is not considered part of the skin. Consists primarily of adipose tissue.
the area beneath the surface of the skin and is embedded within the hair follicle.
the region projecting from the surface of the skin.
the keratinized layer of cells that surrounds the cortex and medulla located in the hair shaft and hair root.
the keratinized layer of cells surrounding the medulla located in the hair shaft and hair root
the center keratinized layer of cells located in the hair shaft and hair root.
a collection of well-nourished epithelial cells at the base of the hair follicle
a small nipple of dermal tissue that protrudes into the hair bulb from the peripheral connective tissue sheath and provides nutrition to the growing hair.
a structure formed from both epidermal and dermal cells. Its inner epithelial root sheath, with two parts (internal and external), is enclosed by a thickened basement membrane, the glassy membrane, and by a peripheral connective tissue (or fibrous) sheath, which is essentially dermal tissue.
- Connective Tissue Sheath
- Glassy Membrane
- External Epithelial Root Sheath
- Internal Epithelial Root Sheath
Arrector Pili Muscle
small bands of smooth muscle cells that connect each hair follicle to the papillary layer of the dermis. When these muscles contract, the slanted hair follicle is pulled upright, dimpling the skin surface with goose bumps.
are found nearly all over the skin, expect for the palms of the hands and the soles of the feet. Their ducts usually empty into a hair follicle, but some open directly on the skin surface.
the product of sebaceous glands. It is a mixture of oily substances and fragmented cells that acts as a lubricant to keep the skin soft and moist and keeps the hair from becoming brittle.
exocrine glands that are widely distributed all over the skin. Outlets for the glands are epithelial openings called pores.
Eccrine (Merocrine) Sweat Glands
produce clear perspiration consisting primarily of water, salts, and urea. Under control of the nervous system, they are an important part of the body's heat-regulating apparatus.
found predominantly in the axillary and genital area. Odor comes from the bacteria living on the skin breaking down the organic components of sweat.