Chapter 5 Flashcards
integumentary system
consists of the skin and accessory structures, such as hair, glands, and nails.
epidermis
Superficial part of skin; stratified squamous epithelium;
composed of four or five strata. Prevents water loss and the entry of chemicals and microorganisms; protects against abrasion and ultraviolet light; produces vitamin D; gives rise to hair, nails, and glands and reduces water loss through the skin.
dermis
Deep part of skin; connective tissue composed of two layers. Is responsible for the structural strength and flexibility of the skin; the epidermis exchanges gases, nutrients, and waste products with blood vessels in the dermis
subcutaneous tissue or hypodermis
Not part of the skin; loose connective tissue with abundant
deposits of adipose tissue. Attaches the dermis to underlying structures; adipose tissue provides energy storage, insulation, and padding; blood vessels
and nerves from the subcutaneous tissue supply the dermis
keratinocytes
what most cells of the epidermis are called because
they produce a protein mixture called keratin, which
makes the cells more durable; give the epidermis its ability to resist abrasion and reduce water loss.
melanocytes
contribute to skin color; irregularly shaped cells with many long processes that extend between the keratinocytes of the stratum basale and the stratum spinosum
Langerhans cells
part of the immune system
Merkel cells
specialized epidermal cells associated with nerve endings responsible for detecting light touch and superficial pressure
keratinization
cells become filled with keratin as they move toward the surface and eventually die and produce an outer layer of dead, hard cells that resists abrasion and forms a
permeability barrier.
psoriasis
skin condition where large scales of epidermal tissue are sloughed off
strata
the regions of which the many layers of cells in the epidermis are divided
stratum basale or stratum germinativum
Deepest stratum of the epidermis; single layer of cuboidal or columnar cells; basement membrane of the epidermis attaches to the dermis.Produces cells of the most superficial strata; melanocytes produce and contribute melanin, which protects against ultraviolet light
stratum spinosum
A total of 8–10 layers of many-sided cells. Produces keratin fibers; lamellar bodies form inside keratinocytes
lamellar bodies
lipid-filled membrane-bound organelles that form inside the keratinocytes.
stratum granulosum
Two to five layers of flattened, diamond-shaped cells. Produces keratohyalin granules; lamellar bodies release lipids from cells; cells die
keratohyalin
nonmembrane-bound protein granules which accumulate in the cytoplasm of the cell.
Stratum corneum
Most superficial stratum of the epidermis; 25 or more layers of dead squamous cells. Provides structural strength due to keratin within cells; prevents water loss due to lipids surrounding cells; sloughing off of most superficial cells resists abrasion
Stratum lucidum
Three to five layers of dead cells; appears transparent; present in thick skin, absent in most thin skin. Disperses keratohyalin around keratin fibers
cornified cells
stratum corneum consists of cornified cells, which are
dead cells, with a hard protein envelope, filled with the protein keratin.
Thick skin
has all 5 epithelial strata, and the stratum corneum
has many layers of cells; found in areas subject to pressure or friction, such as the palms of the hands, the soles of the feet, and the fingertips.
thin skin
covers the rest of the body and is more flexible than thick skin.
callus
the number of layers in the stratum corneum greatly increases to produce a thickened area in skin subjected to friction or pressure
corn
skin over bony prominences may develop this cone-shaped structure
Melanin
group of pigments primarily responsible for skin, hair, and eye color; provides protection against ultraviolet light from the sun.
melanosomes
Golgi apparatuses of the melanocytes package melanin into vesicles called melanosomes, which
move into the cell processes of the melanocytes.
Basal cell carcinoma
the most common type of skin cancer, affects cells in the stratum basale. Some are open sores that bleed, ooze, or crust for several weeks. Others are reddish patches; shiny, pearly, or translucent bumps; or scarlike areas of shiny, taut skin.
actinic keratosis
a small, scaly, crusty bump that arises on the surface of the skin. If untreated, about 2–5% of actinic keratoses can progress to squamous cell carcinoma
squamous cell carcinoma
second most common type of skin cancer. Squamous cell carcinoma affects cells in the stratum spinosum and can appear as a wartlike growth; a persistent, scaly red patch; an open sore; or an elevated growth with a central depression.
Melanoma
least common, but most deadly, type of skin cancer; arise
from melanocytes, so most melanomas are black or brown, but can appear skin-colored, pink, red, or purple
ABCDE rule
signs of melanoma: A - asymmetry (one side of the lesion does not match the other side), B - border irregularity (the edges are ragged, notched, or blurred), C - color (pigmentation is not uniform), D - diameter (greater than 6 mm), and E - evolving (lesion changes over time).
Xeroderma pigmentosum
rare, autosomal recessive trait in which a DNA repair gene is defective.