C: Skin Flashcards
What are the 4 main functions of the skin?
1) Protection
2) Thermoregulation
3) Providing sensory input from outside world
4) Metabolic function (synthesis vit D)
What 2 layers is the skin comprised of?
1) Epidermis - outer epithelial layer
2) Dermis - underlying area of connective tissue
What layer lies deep to the dermis, what does it contain?
Hypodermis or subcutis - layer of loose connective tissue containing variable amounts of fat
How is skin classified as thick or thin?
According to the thickness of the epidermis
How does the presence of hair follicles vary between thick and thin skin?
Thick skin is glabrous (non hairy)
Think skin has hair follicles
The epidermis is made up of what kind of epithelium?
Keratinised stratified squamous epithelium
What are the 5 layers recognised in thick skin?
1) Basal cell layer/ stratum basale/ stratum germinosum
2) Prickle cell layer/ stratum spinosum
3) Stratum granulosum/ granular cell layer
4) Stratum lucidum
5) Stratum corneum/ keratinised squamous layer
Describe the basal cell layer of the skin?
Single layer of basal cells (cuboidal/ low columnar) closet to the dermis
Describe the prickle cell layer/ stratum spinosum?
8-10 layers of keratinocytes, all with lots of desmosomes anchoring cells together and contain thick tufts of intermediate filaments
Describe the granular cell layer?
3-5 layers of cells, cells become gradually flatter as reach the surface, losing their nuclei and organelles and turn into keratinised squamous of next layer
Describe the stratum lucidum?
Thin. transparent layer, difficult to recognise in routine histological sections
Describe the stratum corneum/ keratinised squamous layer?
Layers of dead cells reduced to flattened scales or squames, filled with densely packed keratin, cells are flat and hard to see
What are the 3 types of non-epithelial cells present in the epidermis and what is their rough function?
1) Melanocytes - pigment cells of the skin
2) Langerhans cells - play an immunological role
3) Merkel cells - act as mechanoreceptors
Which of the 5 layers of the skin is absent or very thin in thin skin?
Stratum lucidum
What are the 3 main types of skin cancer and from which layer of the skin does each originate?
1) Basal cell carcinoma - stratum basale
2) Squamous cell carcinoma - stratum spinosum
3) Malignant melanoma - stratum basale
Which type of skin cancer is the least common and most dangerous?
Malignant melanoma
What are warts?
Benign skin growths caused by a viral infection in the skin - hyperkeratonic papules with a rough irregular surface
During development a number of downgrowths from the epidermis invade the underlying dermis to form which 3 structures?
1) Sweat glands
2) Sebaceous glands
3) Hair follicles