S10 Skin and Dermatology Flashcards
What are the three general layers of skin?
- Epidermis
- Dermis
- Hypodermis
What are the layers of the epidermis?
- Stratum Corneum
- Stratum Lucidum (only on palms and soles of feet)
- Stratum Granulosum
- Stratum Spinosum
- Stratum Basale
Is the epidermis vascular or avascular?
Avascular
What is the function of the epidermis?
Prevents water loss, prevents pathogen ingress, prevents underlying tissue loss, synthesis of keratin.
Describe the stratum corneum and where it is found.
Made up of squames (dead keratinocytes).
Always sheds.
Thickest on palms and soles of feet.
What is the stratum lucidum.
A transparent one cell wide layer only present on the palms and soles of feet.
Describe the stratum granulosum and what you find there.
Made up of stratified squamous epithelia.
Contains lamellar granules (make keratin fibres) and tonofibrils.
Describe the stratum spinosum and what you find there.
Made up of 3 layers of cuboidal epithelia held together by desmosomes.
First point at which you find Golgi bodies and where lamellar bodies/granules are produced.
Describe the stratum basale and what you find there.
Made up of columnar epithelial cells.
Where keratinocytes are renewed by cell division. As the cells differentiate they move away from the epidermis-dermis junction and towards the surface.
Contain melanocytes.
Make tonofilaments.
What are the layers of the dermis?
- Papillary dermis
2. Reticular dermis
How do the epidermis and dermis link together?
The epidermis/stratum basale joins the dermis in interdigitations called dermal papillae
What does the dermis contain?
- Sweat glands
- Hair follicles
- Arrector pili muscles
- Sensory structures
- Subeceous glands
What sort of connective tissue makes up the dermis?
Irregular dense connective tissue
What is the function of the dermis?
Helps give the skin structure and involved in thermoregulation
What is the hypodermis made up of?
Mainly adipose tissue and loose connective tissue
Where in men and women is the hypodermis thicker?
Men - thicker around the abdomen and shoulders
Women - thicker around the hips, buttocks and thighs
In both - thick on palms and soles of feet
What does the loose connective tissue of the hypodermis contain?
- Fibroblasts
- Macrophages
- Fibres
- Mast cells
What is the function of the hypodermis?
An energy store, shock absorber, insulator.
Also site of hormone production.
What are melanocytes?
Cells in the stratum basale (epidermis) that produce melanin.
Everyone has the same number of melanocytes but darker skinned people produce more melanin.
What are Langerhans cells?
Dendritic cells in the stratum basale (epidermis).
They present antigens to T-lymphocytes and cause an immune response (e.g. contact dermatitis).
What do keratinocytes produce?
The protein keratin
What are dead keratinocytes called?
Squames