Structure and Function of Skin Flashcards
(49 cards)
What does the integumentary system refer to?
β skin, hair and nails
What are the 5 main skin functions?
β Barrier β Thermoregulation β Sensation β Repair β Vitamin D production
What does the skin act as a barrier against?
β Dehydration
β Infection
β Injury/abrasion
β solar radiation
What are the 3 layers of the skin?
β Epidermis
β Dermis
β Hypodermis
What is the first layer called?
β Stratum basale
Describe the stratum basale?
β Contains stem cells and is attached to the dermis
β daughter cells are constantly moving up distally through the epidermis
β They differentiate as they go until they are shed from the outer surface
What are the characteristics of the stratum spinosum?
β Cells have many desmosomes that are visible as spines between the cells
What does the stratum granulosum contain?
β 1-4 layers of cells containing prominent granules of βkeratohyalinβ - precursor of keratin
β Lamellar bodies containing lipids
β differentiating cells to form the outer layer
What does the stratum corneum contain?
β Squamous cells which have lost their nuclei
β horn-like keratin
β non polar lipids are between the cells
What are the 4 main layers of the epidermis?
β Stratum basale
β Stratum Spinosum
β Stratum Granulosum
β Stratum corneum
What is the stratum corneum constantly doing?
β Flaking off and being constantly replaced
What is keratin the main component of?
β horns, hair, nails, claws, hooves
What are other 3 types of epidermal cells?
β Melanocytes
β Langerhans cells
β Merkel cells
What do melanocytes do?
β Synthesizes melanosomes
β transfers them to basal keratinocytes through long dendrites (downwards)
Where are the stem cells found and why?
β Basal Keratinocytes
β Need to be protected from UV damage
Where is the melanin pigment mostly found?
β Basal epidermis
Where do keratinocytes arrange melanin and how?
β They arrange melanin pigment in a cap distal to the nucleus
β Especially in the basal layer
What is the function of Langerhans cells?
β Antigen presenting cells
β they are also dendritic cells that form a network
Where is vitamin D3 made?
β In the epidermis
β mostly in the basal cells but also the stratum spinosum
What does the production of vitamin D3 require and how does this change with skin color?
β UV light
β more UV light with dark skin
How and where is vitamin D3 converted into its active form?
β 1,25 dihydroxyvitamin D3
β In the liver and kidney
Describe the dermis
β Dense, irregular connective tissue
Why is the dermis dense?
β Full of collagen fibres
Why is the dermis irregular?
β Fibres are running in all directios