Anatomy of the Skin Flashcards
What are the four accessory structures of the skin?
Hair
Sweat Glands
Receptors
Nails
Where is the hair found and what is it made of?
All over the body except palms, soles and lips
Made of dead, keratinised cells produced inside a hair follicle
Hair shaft (dead part) is projected out from the follicle (below visible surface)
What is the arrector pilli muscle?
A muscle found in the hair that contracts to produce goose bumps, it pulls on hair follicle making hair shaft stand upright and trapping tiny packets of air, increasing insulation
What is the root hair plexus?
A collections of sensory nerves found at the base of each hair follicle which heighten sensation. Nerve endings command follicle to contract or release
What are sebaceous glands?
Glands that produce oily secretion called sebum. Made of epithelial cells
What is sebum?
Sebum nourishes hair shafts and naturally moisturises skin. It is also a water repellent due to it being an oily secretion
How does acne occur?
Blocked hair follicles + infection due to increased sebum production leads to acne
What is lanolin?
Sheep sebum which can be purified and used commercially in skin care products
What are the two types of sweat glands?
Eccrine and Apocrine
What is an eccrine sweat gland?
Found in most areas of skin, pours water directly onto the skin surface, important in thermo regulation and excretion, has some antibacterial action
What is an apocrine sweat gland?
Found in specific areas e.g. armpit, groin and around nipples
Secretes sticky/oily and sometimes odorous secretions into base of hair follicle (not directly on skin surface)
Influenced by hormones e.g. lactation
What are the three times of receptors?
Tactile
Lamellar
Bulbous
Receptors allow us to pick up an array of sensations
Why are nails important in regards to skin?
Protect fingertips/toes
Enhance sensation
Sensory receptors require deformation and nails allow this in the form of temporary deformation rather than permanent
How does skin anatomy relate to its function?
Aging
Pigmentation (protection from UV radiation, vit D production)
Skin cancer/Vit D insufficiency
Tattoo (artificial pigmentation)
What are the six components of skin aging?
Thin epidermis
Thin dermis
Slower skin repair
Drier epidermis
Impaired cooling
Less pigmentation
How does a thin epidermis occur with aging?
Cells divide much slower and less frequently resulting in thinner layers of epidermis
How does a thin dermis occur with aging?
Reticular layer in dermis contains collagen and elastin. Replenished more slowly hence less collagen and elastin resulting in sagging/wrinkling
How does slow skin repair occur with aging?
Less blood flow and less nutrients results in longer repair time
How does a drier epidermis occur with aging?
Less sebum is produced due to less blood flow resulting in dry skin
How does impaired cooling occur with aging?
Sweat glands cannot produce as much sweat hence body cannot thermoregulate as quickly
How does less pigmentation occur with aging?
Melanin cells produce melanin slower due to less blood flow resulting in pale skin and grey hair
How does tobacco cause premature skin aging?
Contains agents that accelerate aging, damages collagen and elastin, linked with poor wound healing, acne, skin and oral cancer
How does vaping cause premature skin aging?
Contains nicotine which reduces blood circulation in the dermis, contact dermatitis (skin inflammation) due to metal coating on e-cigarettes
How do melanocytes and melanosomes relate to melanin?
Melanin is produced in melanocytes which are transferred around skin in vacuoles by melanosomes
Melanin pigment absorbs UV light protecting cells from UV damage
What are melanocytes in epidermal pigmentation?
Cells found in the stratum basale hence are not shed
Density varies throughout body and through time
What are melanosomes in epidermal pigmentation?
Cells found throughout the epidermis
Shed with keratinocytes
How is a mole formed?
A mole is a cluster of melanocytes, over-proliferation can be caused by sun exposure
How is a freckle formed?
Melanocytes overproducing melanosomes which is triggered by sun exposure
Disappear with aging or from reduced sun exposure
How is skin pigmentation related to UV exposure?
The more UV exposure, the more skin pigmentation (more UV more melanosomes produced)
What is vitamin D?
Vitamin D is essential for normal calcium metabolism and strong bones, deficiency causes rickets (loss of bone strength), affects mood
How is vitamin D related to UV exposure?
UV exposure in skin is required for vitamin D synthesis
Greater incidence of lightly pigmented skin at higher latitudes e.g. Russia
Highly pigmented people are more susceptible to Vit D deficiency, particularly at extreme latitudes as melanin can block UV so more UV required when more melanin present
NZ and skin cancer facts
- Large proportion (74%) of NZ’s are Pakeha
- Intense UV light due to thin Ozone, similar to Australia
- Highest rates of skin cancer world wide
What is a basal cell carcinoma?
A type of skin cancer that is common but relatively benign, originates in stratum basale, spread (metastasis) is rare
What is a malignant melanoma?
A type of skin cancer that is rare but deadly, originates in melanocytes hence highly spread (metastatic), mortality rate dependent on tumour (thicker tumour=higher death rate)
How do tattoos relate to skin anatomy?
Artificial pigmentation (ink) is deposited deep within the skin in the dermal layer hence it is not shed
Ink captured inside immune cells/scar tissue
Pain during tattoo is due to dermal layer containing pain receptors and free nerve endings
