The Integumentary System Flashcards
Skin
The body’s largest organ and is the main barrier between you and the outside world.
Layers of the skin
epidermis and dermis
The epidermis
composed of epithelial cells and is the outermost protective layer of the body; non-viable
the epithelial layer
thick, keratinized stratified squamous epithelium
The dermis
the bulk of the skin and is a tough, leathery layer composed mostly of dense connective tissue; vascularized
Epidermal cells
Keratinocytes, Melanocytes, Dendritic cells, Tactile epithelial cells
Keratinocytes function
main cell type; produces keratin
Keratin
protein; strength, sturdiness, and waterproofing of the cell
Epidermal growth factor
a hormone that stimulates mitotic activity in the deepest layer of the epidermis (producing new keratinocytes)
Callus
forms when persistent friction occurs causing a thickening of the epidermis.
Melanocytes function
spider-shaped epithelial cells; synthesize the pigment melanin which is found in the deepest layer of the epidermis
Melanosomes
melanin is made in these membrane-bound granules and is transferred through branching processes to adjacent keratinocytes
Melanin function
provide pigment to the skin and protection from UV rays when out in the sun
Dendritic cell function
star-shaped; ingest foreign substances (macrophages- taking up cellular debris/waste and breaking it down) and activate the immune system
Tactile epithelial cell function
touch receptors; Intimately associated with a disc-like sensory nerve ending
Subcutaneous tissue
tissue found immediately under the skin (deep to the skin)
Subcutaneous tissue function
Anchors skin to underlying structures with the ability to slide, an insulator that reduces heat loss, and a shock absorber
Adipose tissue
absorbs physical damage/ shock & stores fat
Layers of the epidermis in thin skin (deep to superficial)
stratum basale, stratum spinosum, stratum granulosum, and stratum corneum
Layers of the epidermis in thick skin (deep to superficial)
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, and stratum corneum
Stratum basale
The basal layer; consists of a single row of stem cells, continually renewing cells, 10-25% of the cells are melanocytes and dendritic cells are seen as well
Stratum Spinosum
The prickly layer; Several cell layers of keratinocytes thick, Dendritic cells are the most abundant in this epidermal layer, contains bundles of intermediate filaments made of pre-keratin
Stratum Granulosum
The granular layer; Thin layer- consists of 1 to 5 layers, Keratinization (cell is filled with keratin) begins here
Keratohyaline granules
help to form keratin in upper layers
Lamellar granules
contain a water-resistant glycolipid that is secreted into the extracellular space; retains water in epidermis
Stratum lucidum
The clear layer; extra layer only found in thick skin, just 2-3 rows of clear, flat, dead keratinocytes
Stratum Corneum
The horny layer; Outermost epidermal layer, mostly dead cells, protect skin, cells shed regularly
Layers of the dermis
The papillary and reticular layer
Papillary layer
The thin, superficial layer (20 %); areolar connective tissue
Dermal papillae
peglike projections from the dermis surface to the epidermis; contains capillaries & nerve endings for touch + pain
Dermal Ridges
found in thick skin such as on palms of hands, fingers, and soles of the feet
Friction Ridges
enhance our ability to grip certain kinds of surfaces (where fingerprints and footprints come from)
Reticular layer
The thicker, deeper layer (80 %); Coarse, dense irregular connective tissue, thick bundles of collagen fibers are found here
Flexure lines
dermal folds that occur at or near joints, where the dermis is tightly secured to deeper structures - skin cannot slide easily in these areas (ex. Palms of hands, fingers, and wrists)
Stretch marks (striae)
skin overstretched rapidly which can tear the dermis (ex. Pregnant women)
Blisters
caused by short term acute trauma (ex. Burns or repeated friction), skin becomes white and bubbly with fluid
Melanin
A polymer made from the amino acid tyrosine; a range of colour comes in 2 forms: reddish yellow to brownish-black
Carotene
Yellow to orange pigment found in plant products (ex. carrots); Pigment deposits in keratinocytes (especially the stratum corneum) & hypodermis
Hemoglobin
The pinkish pigment of fair skin is from the crimson colour of oxygenated hemoglobin (a pigment found in RBC)
Cyanosis
when there is an oxygen deficiency in hemoglobin the cell turns bluish-purple colour in turn making the skin of a fair person bluish-gray; can be a sign of respiratory or cardiovascular problems
Function of hair
sense insects on the skin, guards the head against physical trauma, heat loss, and sun; Shields eyes, filter particles from inhaled air
Parts of the hair shaft
medulla, cortex, and cuticle
Medulla
large cells separated by air spaces, the only part that contains soft keratin; absent in fine (vellus) hair
Cortex
several layers of flattened keratinocytes, the bulky layer that surrounds the medulla; pigment is found here
Cuticle
a single layer of overlapping cells, the most heavily keratinized part of the hair, provides strength and keeps the inner layers tightly compacted
Split ends
keratin fibrils enter the cortex and the medulla begins to frizz which causes split ends (raised cuticle layer)
Hair shaft
the part that projects from the skin - has 3 layers (medulla, cortex, cuticle)
Hair root
The part embedded in the skin (contained within hair follicle)
Hair bulb
the expanded deep end of the follicle - has papilla & root hair plexus (sensory nerve endings)
Hair follicle
outer CT root sheath & inner epithelial root sheath; hair matrix (hair growth occurs here)
Arrector pili muscle
contract to pull hair up & dimple skin, when contracted goosebumps occur
Sebaceous gland
a holocrine gland that secretes sebum
Sebum
oily- lubrication & waterproofing; bactericidal- protects the skin from bacteria and makes hair smoother
Vellus hair
Body hair of children and adult females (pale and fine)
Terminal hair
coarser, longer hair of the eyebrows, eyelashes, and scalp (appears in the axillary and pubic regions of both sexes at puberty and on the face, chest, arms, and legs of males)
Hirsutism
facial hair growth in females due to elevated testosterone production
Alopecia
auto-immune attack towards hair follicles to inhibit hair growth (hair loss); as well as through age
Male pattern baldness
altered response of hair follicle to androgen that shortens growth cycles; genetically-determined and gender-influenced
Nails
made up of hard keratin; scale-like modifications of epidermis - protective, useful tool
lunula(lunule)
the white area on the nail- covers the nail matrix; where nail growth occurs
Yellow-tinged nails
fungal infection or a serious respiratory or thyroid gland disorder
Thickened + yellow-tinged nails
a fungal infection
Spoon nail
possible iron deficiency
Beau’s lines
malnutrition (sporadic stoppage of matrix growth)
Types of sweat glands
eccrine and apocrine
Eccrine glands
most common sweat gland; found predominantly in palms, soles, and forehead
Make up of sweat
99% water plus salts, vitamin C, antibodies, dermcidin, traces of metabolic wastes like urea, uric acid, ammonia
Apocrine
approx 2000 found in axillary & anogenital regions; larger; ducts empty into hair follicles
Ceruminous glands
secrete wax (cerumen) in the external ear canal
Mammary glands
secrete milk