A&P Lab 7: The Integumentary System Flashcards
Epidermis
outer, superficial layer of the skin
Dermis
inner, deep layer of the skin
Hypodermis
tissue beneath the dermis (subcutaneous layer); not a part of the skin, but instead a loose configuration of fat and areolar tissue that attaches the skin to the underlying muscles
Keratinocytes
cells that make up roughly 90% of the epidermal cells and undergo keratinization
Melanocytes
produce the brown pigment, melanin
Langerhans cells
phagocytic cells that provide defense against infection
Merkel cells
located deep in the dermis and function as touch receptors
Stratum basale
single layer of cells adjacent to the dermis, which are columnar or cuboidal in shape and activetly produce new cells by mitosis
Stratum spinosum
8-10 rows of cells, mainly keratinocytes; has the appearance of spines protruding from the cells, caused by the tissue preparation process
Stratum granulosum
3-5 rows of keratinocytes; the flattened cells contain tiny granules (keratohyaline & lamellated granules) in the cytoplasm, a sign that the cells are producing keratin as part of the keratinization process
Stratum lucidum
3-5 rows of flattened, dead keratinocyte ghosts that are mainly keratin; the dead cells appear almost translucent; layer only found in the thick skin of the palms/soles
Stratum corneum
thick, outer layer of 25+ rows of flattened, dead keratinoctyes that have become saturated with keratin to produce a touch, water-repellant layer
Papillary region
part of the dermis adjacent to the stratum basale; consists of a thin region of areolar tissue arranged in finger-like ridges poking up toward the epidermis; individual projections = dermal papillae (form the ridges/whorls of the skin surface in the fingers, palms, toes, and soles)
Reticular region
dominant, deep part of the dermis that is composed of dense irregular connective tissue with abundant collagen fibers, elastic fibers, and blood vessels
Hairs
found throughout the surface of the skin, except in the thick-skinned parts of the body (palms/soles), the lips, the nipples, and parts of the external genitals
Shaft
part of a hair that projects from the skin surface
Root
submerged portion of a hair
Hair follicle
sheath of epithelium extending downward into the dermis
Arrector pili muscle
small band of smooth muscle associated with the hair follicle
Hair bulb
well-nourished swelling of germinal epithelial cells
Matrix
new cells are produced at the hair bulb within a cluster of cells known as this, which push upward from the growth area and eventually die and become keratinized
Papilla
cells of the matrix receive nourishment from blood vessels within a connective tissue _______
Medulla
central core of a hair
Cortex
outer region of keratinized cells that surround the medulla
Cuticle
outer protective layer of keratinized cells that surround the cortex
Nail
flat, hart structure composed of keratinized epidermis
Body
visible, pink portion of the nail
Root
part of the nail that is embedded in the skin that attaches to the epidermis
Free edge
at the distal end of the body extending away from attached areas is this
Nail matrix
at the proximal end of the body containing the germinal cells that divide to produce this new nail material
Lunula
lighter part of the nail body at the proximal end
Cuticle
AKA eponychium; skin folding over the proximal end of the nail
Sebaceous glands
produce an oily product (sebum), which is deposited into ducts that usually empty into hair follicles; found wherever hair follicles are present
Sweat glands
AKA sudoriferous glands; located deep in the dermis where they produce a watery material; the product is deposited into long ducts that empty onto the skin surface at pores
Eccrine glands
widely distributed, produce watery perspiration as a means of regulating body temperature
Apocrine glands
produce a thickened secretion after puberty and are found mainly in the axillary and genital regions
Sensory receptors
specialized endings of sensory neurons that generate and electrochemical signal when they experience a change in the environment (temperature, pressure, or fine touch)
Meissner’s corpuscles
Corpuscle of Touch in the papillary region of the dermis; sensitive to fine touch; rod-shaped swellings at the end of sensory neurons adjacent to the stratum basale of the epidermis
Pacinian corpuscles
AKA Lamellated corpuscle; in the reticular region of the dermis; sensitive to pressure; large, round swellings with numerous rings of protein fibers, giving them the appearance of a sliced onion in a section through the skin