Integumentary System Flashcards
(43 cards)
What are the functions of integument?
- protection (keratinized stratified squamous epithelium)
- excretion of salt, water, and organic wastes (sudoriferous glands -sweat glands)
- systhesis of vitamin D3 for Ca absorption (skin cells)
- detection of touch, pressure, pain, and temperature (nerve endings)
What is the S&F of the epidermis?
- tissue: keratinized stratified squamous epithelium
- cell division and renewal because its the deepest layer closest to capillaries and nutrients
- new cells push older cells to surface where they shed
What is the most common cell type in the skin?
-keratinocytes
How many days does it take from division to shedding?
- 30-56 days
- varies in age and response to injury
What are the characteristics of epidermis in thin skin?
- thin stratum corneum, few layers of ells
- 4 sublayers
- 20-30 layers of cells
What are the characteristics of epidermis in thick skin?
- think stratum corneum (many layers of dead cells)
- 4 sublayers and stratum lucdium
- 30-60 layers of cells
Name the layers in thin skin
Stratum corneum
Stratum granulosum
Stratum spinosum
Stratum basale
Name the layers in thick skin
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
What is the S&F of the stratum corneum?
- 15-30 layers of dead keratinized cells
- connected by desmosomes, tight junctions
- shed ofter approx. every 2 weeks
- water resistant but NOT water proof
What is the S&F of the stratum lucidum?
- only in think skin (fingertips, palms, soles)
- clear layer of flattened, densely packed keratinized cells
What is the S&F of the stratum granulosum?
- 3-5 layers of keratinocytes
- make strong fibrous keratin protein = fills and flattens cells
- nuclei and organelles degenerate
- cells have granules that release lipids onto the surface, blocking water and preventing dehydration
- cells above lipid barrier are dying, dead
What is the S&F of the stratum spinosum?
- 5-10 layers of living, dividing keratinocytes
- produce vitamin D in response to UV –> vitamin D required for Ca absorption in intestine
- dendritic cells
What is the S&F of the stratum basale?
-one layer of cells attached to the basement membrane
-closest to diffusing nutrients
basal (stem) cells divide to replenish keratinocytes
-Markel cells
-Melanocytes
What are Markel cells?
- touch receptors
- stimulate nerve endings
What are dendritic cells?
-patrol and defend pathogens eg. skin cancer
What are melanocytes?
- turn amino acid tyrosine into melanin pigment –> protects against UV
- packed into vesicles = melanosomes
- melanosomes transferred to keratinocytes
- keratinocytes pigmented until melanosomes fuses with lysosome
What is skin colour?
-depends on number, size, and distribution of melanosomes, and type of melanin pigment
What is the papillary layer?
- the top 20% of the dermis
- aereolar connective tissue
- contains: capillaries, sensory neurons, Meissener’s corpuscle, dendritic cells and other WBC
- dermal papillae
What is dermal papillae and how do they create fingerprints?
- in papillary layer of dermis
- increase SA in contact with epidermis
- in thick skin dermal papillae lie on top of mounds called “dermal ridges”
- dermal ridges cause epidermis to form epidermal ridges
- epidermal ridges with sweat pores cause fingerprint
- fingerprint ridges increase friction/grip
What is the reticular layer?
- bottom 80% of the dermis
- dense irregular connective tissue
- fills space, provides strength and resiliency
- accessory organs: blood, lymph vessels, nerve fibres
- collagen extends into papillary and subcutaneous layers to anchor
What is the hypodermis?
- subcutaneous layer=superficial fascia
- not part of the integument
What two tissues make up the hypodermis?
- aereolar connective tissue: stabilizes, binds skin to underlying muscle
- adipose tissue: insulates, stores energy
What layer do drug users inject into?
- hypodermis
- arteries, veins act as blood reservoir
- subcutaneous injections allow drugs to enter blood stream
What are the accessory organs of the integumentary system?
-hair, sebaceous glands, sudoriferous glands, Meissner’s corpuscle, Lamellated corpuscle, ceruminous glands, mammary glands, nails
