Skin Anatomy 2 Flashcards
What are the 4 accessory structures
Hair, sweat glands, receptors, nails
Outline Hair
Found all over the body accept alms, soles, and lips
Made of dead, keratinised cells produced inside a hair follicle
Hair shaft projects from follicle
Also consists of erector pili muscle, root hair plexus, and sebaceous glands
What part of hair is dead
Part projecting out of the skin/hair follicle - the hair shaft
Outline the erector pili muscle
contraction produces “goose bumps”. Improves insulation. Pulls shaft upright, trapping small pocket of air - leads to bump appearance
Outline the root hair plexus
Collection of sensory nerves at the base of each hair follicle. Heightened sensation
Outline the sebaceous gland
Produces oily secretion called sebum. Nourishes hair shaft and naturally moisturises skin. Water repellent - property of oils. Blocked hair follicles + infection due to increased sebum production leads to acne
What is the animal equivalent of sebum and what is it commonly used for
Lanolin. Sheep sebum. Purified and used commercially in skin care products
What are the two types of sweat glands
Eccrine and apocrine
Outline eccrine glands
Found in most areas of the skin. Pour watery secretion directly onto the skin surface. Important in thermoregulation and excretion. Some antibacterial action
Outline apocrine sweat glands
Found in specific areas eg armpit, groin, and around nipples. Secrete stick/oily and at times odorous secretions into the base of the hair follicle. Influenced by hormones, eg lactation.
Why do apocrine glands secrete into hair follicle rather than skin surface
Apocrine sweat glands are loaded much more deep than eccrine glands Secreting into hair follicle provides a shorter pathway than travelling all the way to the skin surface.
3 receptor types of skin
Tactile, lamellar, bulbous
3 features of nails
Protect fingertips/toes. Enhance sensation. Sensory receptors require deformation
Outline skin aging.
Thin epidermis. Thin dermis (sagging/wrinkling) - reduced collagen. Slower skin repair. Dryer epidermis (less sebum). Impaired cooling (less sweat). Less pigmentation - pale skin, grey hair
Outline smoking and skin aging
Tobacco smoke causes premature skin aging. Contains agents hat accelerate aging. Damages collagen and elastin in the skin. Linked with poor wound healing, acne, skin and oral cancers
What about vaping on skin aging
Contains nicotine. Nicotine reduce blood circulation in the dermis. Contact dermatitis (skin inflammation) due to metal coating on e cigarettes
Outline skin pigmentation, melanocytes, and melanosomes
Melanin pigment absorbs UV light - protects cells from UV damage
Produced in melanocytes
Transferred to epidermal cells by melanosomes - vesicles containing melanin
Where are melanocytes located
Located in stratum basale
Where are melanosomes found throughout
Found throughout the epidermis - shed with keratinocytes
Outline the density of melanocytes
Varies throughout the body and through time
Outline the difference between a mole and a freckle
Mole - cluster of melanocytes. Over-proliferation can be caused by sun exposure
Freckle - Melanocytes overproducing melanosomes. Over-production triggered by sun exposure. Can reduce with age
Outline skin pigmentation matching UV exposure
Indigenous populations closer to the equator = more sun = more UV = more melanin = darker pigmentation
Outline Vitamin D
Vitamin D is essential for normal calcium metabolism and strong bones. UV exposure in skin is required for vitamin D synthesis. Likely explains the greater incidence of lightly pigmented skin at higher latitudes
What can Vitamin D deficiency cause
Rickets and effects mood
Outline when pigmentation does not match UV exposure
Highly pigmented people are more susceptible to vitamin D deficiency, particularly at extreme latitudes.
Outline Basal cell carcinoma
Common but relatively benign. Originates in stratum basale. Metastasis (spread) is rare. Stratum basale regenerative stem cell
Outline malignant melanoma
Rare but deadly if not treated. Originates in melanocytes (pigmented). Highly metastatic. Mortality rate dependent upon tumour.
Outline artificial pigmentation of tattoo
Artificial pigmentation deposited into the dermal layer of the skin, not shed. Captured (but not broken down) inside immune cells/scar tissue.
What are the types of tattoos
Trauma, decorative, cosmetic
Sebum is an oily secretion produced by
Sebaceous gland
Melanocytes are found in the stratum basale
Moles are caused due to over proliferation of melanocytes
The two types of swear glands are
Eccrine
Apocrine
Vitamin D is essential for ___________ metabolism and its defficiency causes
Rickets
Outline thin epidermis in terms of skin aging
With age, stratum basale regenerative stem cells rate of division significantly reduces. Less layers refreshed, epidermis layer becomes thinner with age
What causes saggy/wrinkling skin
Reticular layer of dermis contains collagen and elastin fibres - conform strength to region. Collagen/elastin regeneration slows with age, decreased levels result in saggy/wrinkly skin. Less collagen/elastin, as well as reduced vascularity, results in thin dermis.
What causes slower skin repair
Less blood flow (due to thinning of dermis). Blood carry’s nutrients/healing factors required for recovery from injury.
What causes drier epidermis and impaired cooling
Less blood supply slows down sebaceous gland and sweat gland activity.
Lack of sebum results in dried out epidermis, lack of sweat gland activity results in less evaporative cooling
Skin aging and pigmentation
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