Basics - Skin anatomy Flashcards
Skin layer
Epidermis
Dermis
Subcutaneous
Epidermal layers
Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale
About Epidermis
- Avascular
- Where is the youngest cells
- Cells progress from where to where
- 1 for how long
- Explain each layer
- Cell types of the epidermis
Avacular: receives its nutrition from the dermal capillaries
- youngest at stratum basale
- Form basale to corneum in 4 wk
- Dermis layers
- The role of each layer
- Cells and dermis
- Papillary and reticular
- Papillarypapillary: contains numerous capillaries that supply nutrients to the dermis and epidermis.
reticular: provides a strong structure for skin; consists of collagen bundles woven together
along with elastic bres, broblasts, and macrophages - broblasts: produces collagen, elastin, and ground substance
mast cells: releases histamines which mediate type I hypersensitivity
Subcutaneous tissue: (subnormal)
Consists of …
consists primarily of adipose cells, larger caliber vessels, nerves and fascia
pilosebaceous unit =
pilosebaceous unit = hair + hair follicle + sebaceous gland + arrector pili muscle
Types of Cutaneous Glands:
sebaceous gland
apocrine sweat gland
eccrine sweat gland
About sebaceous gland:
- sebaceous glad is part of what unit?
- what does produce?
- where does it covers?
-part of pilosebaceous unit, produces sebum which is secreted into the hair follicle via the sebaceous duct, where it covers the skin surface (protective function)
- sebum has some antifungal properties
- these glands cover entire skin surface and are absent only in non-hair bearing areas (e.g.
palms, soles, lips)
About apocrine sweat gland:
- apocrine duct empties into hair follicle above sebaceous gland
- found in axillae and perineum
- likely a vestigial structure, functions in other species to produce scent (e.g. pheromones)
About eccrine sweat gland:
- is it part of pilosebaceous unit?
- Where can be found?
- what is its importance?
- not part of pilosebaceous unit
- found over entire skin surface except lips, nail beds, and glans penis - important in temperature regulation via secretion of sweat to cool skin surface
Skin Function
name them and how
• protection
- due to continuous recycling and avascularity of epidermis
-barrier to UV radiation, mechanical/chemical insults, pathogens, and dehydration
• thermal regulation
- insulation to maintain body temperature in cool environments via peripheral
vasoconstriction, hair, and subcutaneous adipose tissue
- dissipation of heat in warm environments via increased activity of sweat glands and
increased blood ow within dermal vascular networks
• sensation
- touch, pain, and temperature sensation
• metabolic function
- vitamin D synthesis
energy storage (mainly in the form of triglycerides)
Definition :
- Primary Morphological Lesions
- Secondary Morphological Lesions
Def:
- an initial lesion that has not been altered by trauma or manipulation and has not regressed
- develop during the evolutionary process of skin disease, or created by manipulation, or due to complication of primary lesion (e.g. rubbing, scratching, infection)
Types of Primary Morphological Lesions
- Flat lesion: Macule (< 1 cm diameter) (e.g. freckle), Patch (>= 1 cm diameter) (e.g. vitiligo)
- Deep palpable (dermal or subcutaneous): Nodule (< 1 cm diameter) (e.g. dermatofibroma), Tumour (>= 1 cm diameter) (e.g. lipoma)
- Raised superficial lesion: Papule (< 1 cm diameter) (e.g. Wart), Plaque (>= 1 cm diameter) (e.g. psoriasis)
- Elevated fluid-filled lesions: Vesicle (< 1 cm diameter) (e.g. HSV), Bulla (>= 1 cm diameter) (e.g. bullous pemphigoid)
Secondary Morphological Lesions
• crust: dried uid (serum, blood, or purulent exudate) originating from a lesion (e.g. impetigo)
• scale: excess keratin (e.g. seborrheic dermatitis)
• licheni cation: thickening of the skin and accentuation of normal skin markings (e.g. chronic
atopic dermatitis)
• ssure: a linear slit-like cleavage of the skin
• excoriation: a scratch mark
• erosion: a disruption of the skin involving the epidermis alone; heals without scarring
• ulcer: a disruption of the skin that extends into the dermis or deeper; heals with scarring
• xerosis: pathologic dryness of skin (xeroderma), conjunctiva (xerophthalmia), or mucous
membranes
• atrophy: histological decrease in size and number of cells or tissues, resulting in thinning or
depression of the skin
Other Morphological Lesions: • cyst: • pustule: • scar: • wheal: • comedones: • petechiae: • purpura: • ecchymoses: • telangiectasia:
• cyst: an epithelial-lined collection containing semi-solid or uid material
• pustule: an elevated lesion containing purulent uid (white, grey, yellow, green)
• scar: replacement brosis of dermis and subcutaneous tissue (hypertrophic or atrophic)
• wheal: a special form of papule or plaque that is transient (<24 h) and blanchable o en with a
halo and central clearing, formed by edema in the dermis (e.g. urticaria)
• comedones: collection of sebum and keratin
open comedo (blackhead)
closed comedo (not a pustule; rather a minute dome shaped skin coloured papule)
• petechiae: small pinpoint extravasation of blood into dermis resulting in hemorrhagic lesions;
non-blanchable, <3 mm in size
• purpura: larger than petechia, 3 mm-1 cm in size
• ecchymoses: larger than purpura, >1 cm in size (i.e. a “bruise”)
• telangiectasia: dilated super cial blood vessels; often branching and reticulated and of small
caliber
