Lecture 19 Flashcards
Where is the adipose tissue located in the skin?
Hypodermis
Skin layers?
Epidermis
Dermis- hair follicles, sebaceous glands etc
Hypodermis- adipose tissue…. hypodermis also known as sub cutaneous layer and injections are given here
Hypodermis function?
Insulation
Energy store
Shock absorber
Makes hormones
Dermis function?
Sweat glands and hair follicles
Gives structure to skin and so body shape
Epidermis function?
Four layers of cells and 5 layers in thick skin. No blood vessels.
Prevents water loss
Prevents pathogen ingress makes keratin
Regents tissue loss from abrasion
Stratum corneum layer?
Contain keratin
Thick on palms and soles of feet
Stratum granulosum layer?
Stratified squamous
Makes keratin
Stratum spinosum?
Cuboidal epithelium
Stratum basale or basal cell layer?
Columnar cells
Renew keratinocytes
Where melanocytes found
What causes psoriasis?
Keratin synthesised by keratinocytes. Transit type to surface (stratum corneum) usually 28-40 days but in psoriasis is 2-3 days. Results in silvery scales
What are the important cells of the epidermis?
Melanocytes- produce melanin, don’t increase in number in black or tanned skin
Langerhans cells- present antigens to T lymphocytes= immune response
Merkel cells-mechanoreceptors responsible for touch
What are the two skin types?
Hairy or think skin and non hairy or thick skin
Lips and parts of genitalia are exceptions
Main differences are just sweat glands and hair follicles
What are the three types of hair?
Lanugo- covers foetus
Vellus- replaces lanugo eg back of hands
Terminal- thick hair on scalp and nasal passageway etc
Functions of hair?
Thermoregulation
Sexual attraction- pheromones and hair style
Sensation- sensory nerve endings within the bulb
Protection- eg eyelashes
What makes hair stand up?
The arrector pili muscle
What mechanoreceptors can be found in the skin?
End bulbs- thermoreceptors
Free nerve endings- have nociceptors which register pain
Tactile discs- sense touch, pressure and texture
Ruffini’s corpuscle- joint movements and tissue stretch
Root hair plexus- vibrations in hair shaft
What about nails?
Found on distal surface of pharanges
Enhances fingertip sensitivity
Enhances precise delicate movements
Protects distal phalanx
Finger nail growth is correlated to length of pharynx
What protects against UV?
Melanocytes
Skin functions summary?
Protection and repair
Thermoregulation
Sensation
Absorption
Storage
Vitamin D synthesis
Lubrication
Aesthetics
What skin condition can be caused by vitamin A deficiency?
Hyperkeratosis- abnormal thickening of outer skin layer (keratin layer)
