Ch. 5 Flashcards
(52 cards)
Integumentary system
Consists of skin and accessory structures, such as hair, glands and nails.
FUNCTIONS:
- Protection
- Sensation
- Temperature regulation
- Vitamin D production
- Excretion
What are the 2 major tissue layers of the skin?
Epidermis & Dermis
Epidermis
Superficial layer of the skin
consisting of stratified squamous epithelial tissue / seperated from dermis by basement membrane / no blood vessels
Cells are keratinocytes which produce keratin
Melonscytesproduce pigment / color
Langerhans cells part of immune system
Merkel cells specialized cells associated with nerve endings responsible for detecting light touch
-Protects against damage from abrasion and reduces water loss
Dermis
A layer of connective tissue
Epidermis rests on the dermis
Responsible for strenght of the skin
Subcutaneous tissue
A layer of loose connective tissue
Skin rests on top of - not part of skin or integumentary system
Connects skin to underlying muscle or bone
What are the cells of the epidermis?
- *Keratinocytes** which produce keratin
- *Melonscytes** produce pigment / color
- *Langerhans** cells part of immune system
- *Merkel cells** specialized cells associated with nerve endings responsible for detecting light touch
Keratinization
Process in which Keratinocytes change shape and chemical composition, where cells accumulate keratin
Cells eventually die and produce an outer layer of dead, hard cells which resist abrasion and forms a barrier
Psoriasis
Skin disease
Large scales of epidermal tissue are sloughed off
Strata
Region
The 5 strata are: Stratum basale, Stratum spinosum, Stratumgranulosum, Stratuml lucidum, Stratum corneum
Stratum Basale
Deepest portion of epidermis
Single layer of cuboidal or columnar cells
Epidermis is anchored to basement membranes by hemidesmosomes
Keratinocytes are strengthened internally by keratin fibers
*Keratinocyte stem cells undergo mitosis every 19 days
Stratum Spinosum
On top of stratum basale
8 - 10 layers of many sided cells
as cells are pushed to the surface they flatten, desmosomes break apart and new ones build
*As karatinocytes progess through the stratum, additional keratin fibers and lamellar bodies form inside the cells
Lamellar bodies
Lipid filled membrane bound organelles
Stratum granulosum
3rd layer up
2-5 layers of somewhat flat diamond shaped cells
Presences of protein granules called Keratohyalin, which accumulate in the cytoplasm of the keratinocyte. Lamellar bodies release their lipids, the keratinocyte dies, keratin fibers and granules within the cytoplasm do not degenerate
Stratum Lucidum
4th layer up / only found in thick skin
several layers of dead keratinocytes, kertain fibers are present, cells appear transparent
Stratum Corneum
Top layer / superficial layer
25 or more dead layers of overlapping squamous cells joined by desmosomes
When the desmosomes break apart the cells shed from the surface of skin
Cornified cells
Dead keratinocytes with a hard protein envelope
Thick skin
Has all 5 epithelial strata
Found: palms of hands, soles of feet and finger tips
Thin skin
Has 4 layers of epithelial strata - missing stratum lucidum
Found: on rest of the body, (minus soles of feet, finger tips and palms of hands)
Callus
Stratum corneum increases in thickness
Usually on an area subject to friction or pressure
Corn
Skin over boney areas develop a cone shaped structure
Melanin
group of pigments responsible for skin, hair and eye color
Melanocytes
Produced melanin
Irregularrly shaped cells with many long processes that extend between the keratinocytes of the stratum basale and stratum spinosum
Melansomes
Vesicles in which melanocytes package melanin
Albinism
Genetically agressive trait that results from inability to produce tyrosinase. Result is the deficiency or absence of pigment of skin, hair and iris of eyes
