Skin Flashcards
What is the epidermis layer of skin composed of
Primarily of keratinocytes
What is the dermis layer of skin composed of
Mainly connective tissue
What is the hypodermic layer of skin composed of
Subcutaneous layer/fat layer
Mainly adipose tissue
What are the 3 layers to skin
Epidermis
Dermis
Hypodermis
What is differentiation
Process in which cell changes from one cell type to another
What is stratification
Squamous epithelial cells arranged in layers upon a basement membrane
What are the 4 structural layers of the epidermis
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum corneum
What epithelium is the epidermis layer
Specialised stratified squamous
What protein does the epidermis contain
Cytokeratin proteins
What makes up 90% of cells
Keratinocytes
How does the epidermis layer adhere to one another
By desmosomes - a cytoskeleton attachment junction connecting cells to one another in epithelia and muscle tissues
How does the epidermis adhere to basement membrane
Via hemidesmosomes
What is the stratum corneum layer
Desquamating keratinocytes layers of flattened non nucleated cells provide a barrier against trauma and infection
What is the granular cell layer
Lipids produced by keratinocytes are secreted into the ECM spaces and forma barrier that retains water in the skin
What is the spinous layer
Appearance due to a combination of desmosome junctions which join keratinocytes and cell shrinkage
What is the basal layer
Site of stem cells high rate of cell division keratinocytes divide here before moving laterally then ascending
How does stratum spinosum work
As cells commit to terminal differentiation they increase in size and switch from the expression of cytokeratin proteins K14/K5 to K1/K10
What type of collagen is basement membrane
Type IV collagen
What 4 items does the basement membrane consist of
Laminin
Collagen
Fibronectin
Hemidesmosomes - integrins
What do melanocytes protect against
UV radiation and ROS
What do melanocytes not contain
Desmosomes
Where are dendritic cells found
In the mid layer of the epidermis
Which type of cell is non dendritic
Merkel cells
What are merkel cells
Basal distribution
Associated with nerve fibres
Sensory function
Contain small, membrane bound vesicles release neurotransmitter
Contain cytokeratins
Desmosomes attach them to keratinocytes
What are langerhans cells associated with
Presentation of antigens to sensitised T lymphocytes significant role on pathogenesis of delayed type hypersensitivity states
Where are lymphocytes found
In mucosal epithelia (e.g oral and gut)
What do mast cells do
Important in the pathogenesis of immediate type hypersensitivity response
What are the 2 layers of the dermis
Papillary dermis
Reticular dermis
What is the papillary dermis composed of
Loose areolar connective tissue
What is the reticular dermis composed of
Dense irregular connective tissue
What does the dermis layer contain
Blood and lymph vessels and nerves supplying the skin and adnexal structures
What is the principle cell type in the dermis
Fibroblast
What is the hypodermis (subcutaneous layer)
Fat layer insulates the body serves as energy supply allows for mobility
What are 4 adnexal structures
Hairs
Erector pili muscles
Sebaceous glands
Sweat glands
What is eccrine
Major sweat glands do not involve hair follicle
What is apocrine
Associated with hair follicles secret a fatty mixture into the gland tubule
What are sebaceous glands stimulated by
Androgens and inhibited by estrogen
They are lipid filled cells
What do pecinian corpuscles sense
Deep pressure
Fast vibrations
What do meisners corpuscles sense
Light tough
Slow vibrations
What do free nerve endings sense
Temp, touch, pain
What do merkels disks sense
Sustained pressure
Hairless skin
What does dry epidermis cause
Reduction in sebaceous gland activity
What do fewer melanocytes cause
Paler skin
Reduced tolerance to sun exposure
What does thin dermis cause
Sagging and wrinkling due to collagen and elastin fibre loss
What does a thin epidermis cause
Slower repair
Decreased vitamin D production
Reduced number of langerhans cells
What does VUB (290-320nm) do
Damaging melanocytes, keratinocytes and causes the production of proteolytic enzymes
What does UVA (320-400nm) do
Penetrates deeper than UVB exerts direct effect on both dermis and epidermis
Which is the most common skin cancer
Non melanoma
In what layer are stem cells mainly found
The basal layer
Do epithelial cells have a blood supply
No
