integumentary system
the skin and its accessory structures that guard the body's physical and biochemical integrity, maintain a constant body temperature, and provide sensory information about the surrounding environment
dermatology
the medical specialty dealing with diseases of the skin
skin
the external covering of the body consisting of a superficial, thinner epidermis and a deep, thicker dermis that is anchored to a subcutaneous layer
epidermis
the superficial, thinner layer of skin, composed of keratinized stratified squamous epithelium
dermis
a layer of dense irregular connective tissue lying deep to the epidermis
subcutaneous layer
a continuous sheet of areolar connective tissue and adipose tissue between the dermis of the skin and the deep fascia of the muscles
hypodermis
another name for the subcutaneous layer
Pacinian corpuscle
a type of nerve ending located in the subcutaneous layer that is sensitive to pressure; also described as "lamellated
keratinocyte
the most abundant type of epidermal cell, which helps protect the skin and underlying tissue from heat, microbes, and chemicals
keratin
an insoluble protein that makes up hair and nails
melanocyte
an epidermal cell that produces the pigment melanin which contributes to skin color and absorbs damaging ultraviolet (UV) light
melanin
a dark black, brown, or yellow pigment found in the skin and hair
Langerhans cell
an epidermal dendritic cell that that functions as an antigen-presenting cell during an immune response
Merkel cell
a type of epidermal cell that makes contact with a tactile disc, which functions in touch
thin skin
found in most areas of the integumentary system, with an epidermis consisting of four layers of keratinocytes
thick skin
found in areas of the integumentary system exposed to significant friction, with an epidermis consisting of all five layers of keratinocytes
stratum basale
the deepest layer of the epidermis consisting of stem cells capable of undergoing cell division to form new cells
stratum spinosum
a layer of the epidermis that provides strength and flexibility to the skin
stratum granulosum
a layer of the epidermis that marks the transition between the deeper, metabolically active strata and the dead cells of the more superficial strata
stratum lucidum
a layer of the epidermis found only in the thick skin of the fingers, palms, and soles
stratum corneum
the most superficial layer of the epidermis consisting of dead cells
callus
an abnormal thickening of the epidermis caused by constant exposure to friction
keratinization
the replacement of cell contents with new protein, occurring as cells move to the skin surface over 2-4 weeks
psoriasis
a chronic skin disorder characterized by a rapid division and movement of keratinocytes through the epidermal strata
papillary region
the superficial area of the dermis composed of areolar connective tissue, dermal papillae, Meissner corpuscles of touch, and free nerve endings
dermal papilla
a fingerlike projection of the papillary region of the dermis that may contain blood capillaries or Meissner corpuscles (of touch)
Meissner corpuscle
a tactile nerve ending receptor in the dermal papillae that is sensitive to touch
free nerve ending
dendrites that lack any obvious structural specialization; used to generate sensations of warmth, coolness, pain, tickle, and itch
reticular region
the deeper part of the dermis consisting of dense irregular connective tissue containing bundles of collagen fibers and some elastic fibers
extensibility
the ability of skin to stretch, due to the combination of collagen and elastic fibers in its reticular region
elasticity
the ability of a tissue to return to its original shape after contracting or stretching
epidermal ridge
this can help increase friction for improved grasping ability and provides the basis for fingerprints and footprints
hemoglobin
the oxygen-carrying pigment in red blood cells that provides the pink to red color of the epidermis
carotene
yellow-orange pigment present in the epidermis, accounting for the yellowish coloration of skin
albinism
an abnormal, nonpathological, partial, or total absence of pigment in skin, hair, and eyes
vitiligo
the complete or partial loss of melanocytes from patches of the skin resulting in irregular white spots
cyanotic
the bluish color of the mucous membranes, nail beds, and skin that occurs when blood is not picking up an adequate amount of oxygen from the lungs
jaundice
a yellowish appearance to the skin and whites of the eyes due to a buildup of the pigment bilirubin
erythema
skin redness usually caused by dilation of the capillaries
pallor
the paleness of skin resulting from shock or anemia
pilus
found on most skin surfaces except the palms, palmar and plantar surfaces of the digits, and soles
shaft
the superficial portion of the hair
root
the portion of a hair that penetrates into the dermis and sometimes the subcutaneous layer
hair follicle
a structure composed of epithelium that surrounds the root of a hair
bulb
the base of a hair follicle and its surrounding dermal root sheath, containing the papilla of the hair and matrix
arrector pili
the smooth muscles attached to hair follicles
hair root plexus
a collection of dendrites of neurons surrounding each hair follicle that are sensitive to touch
alopecia
the partial or complete lack of hair resulting from genetic factors, aging, endocrine disorders, chemotherapy, or skin disease
lanugo
the fine, nonpigmented, downy hairs that cover the fetus
terminal hair
hair located on the head, eyelashes, and eyebrows
vellus hair
short, fine, pale hair ("peach fuzz") that replaces lanugo
sebaceous gland
an exocrine gland in the dermis associated with a hair follicle that secretes oil (sebum)
sebum
the lipid-rich secretion of the sebaceous glands that moistens hair, waterproofs and softens the skin, and inhibits bacterial growth
sudoriferous gland
an exocrine gland that produces and secretes perspiration
thermoregulation
the homeostatic balance of body temperature
ceruminous gland
a modified gland in the external auditory meatus that secretes earwax
cerumen
earwax
nail
the hard, keratinized epidermal cells located over the dorsal surfaces of the terminal portions of the fingers and toes
nail body
the visible portion of the nail
nail root
the portion of a nail that is buried in a fold of skin
lunula
the moon-shaped white area at the base of a nail
eponychium
a narrow band of epidermis at the proximal border of a nail; the cuticle
nail matrix
the part of the nail beneath the body and root from which the nail is produced
blood reservoir
a function of the skin provided by the extensive network of blood vessels in the dermis
cutaneous sensation
a feeling of touch, pressure, vibration, tickle, heat, cold, or pain that arises in the skin
excretion
the elimination of metabolic wastes from the body
contact inhibition
a cellular response where epidermal cells stop migrating upon encountering each other
inflammatory phase
the stage where a blood clot forms in a deep wound and loosely unites the wound's edges
inflammation
a vascular and cellular response that helps eliminate microbes, foreign material, and dying tissue in preparation for repair
migratory phase
the stage in wound healing where the blood clot becomes a scab, and epithelial cells migrate beneath the scab to bridge the wound
granulation tissue
the cells that divide to restore skin after an injury
proliferative phase
the stage in wound healing characterized by extensive growth of epithelial cells beneath the scab, deposition of collagen fibers by fibroblasts, and continued growth of blood vessels
maturation phase
the stage in wound healing where a scab sloughs off once the epidermis has been restored to its normal thickness