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78 Cards in this Set
- Front
- Back
what is the anatomy of the epidermis and dermis |
Keratinised epidermis is derived from basal cells. Cells adhere via desmosomes. Epidermal cells are keratinocytes, melanocytes and Langerhans cells. Langerhans cells are antigen-presenting cells. The basement membrane zone is a complex interaction of differing proteins. Dermis is mainly composed of collagen, also elastin, hyaluronic acid and cells. Subcutaneous tissue stores fat. Appendages are hair, nails, sebaceous glands, eccrine and apocrine glands. Hair and nails are formed from keratinised cells.Phases of the hair cycle are anagen, catagen and telogen. Skin pH 5.5 is protective against microbial attack. Skin colour depends on melanin and other pigments. |
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Functions of the skin include |
barrier function, maintenance of fluid balance, regulation of body temperature, vitamin D synthesis and social communication. |
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the thinnest sites of skin are the |
eyelids and scrotum |
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the thickest sites of skin are the |
soles and palms |
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Skin is made up of |
Epidermis Basement membrane zone Dermis Subcutaneous tissue Appendages: hair, glands, nails. nb These layers are modified according to the needs of the specific area of the body. For example, the scalp is covered with thick hair, the palms have particularly thick epidermis and the face contains large numbers of sebaceous glands. |
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epidermis is a dynamic structure acting as a |
semi-permeable barrier |
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epidermis is a dynamic structure acting as a semi-permeable barrier with what layer in the surface (ie outter most layer) |
layer of flat “dead” (anuclear) cells at the surface (stratum corneum) |
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the surface ie outter most layer, of the epidermis is the |
stratum corneum |
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The epidermis regenerates in orderly fashion by cell division of |
keratinocytes in the basal layer, with maturing daughter cells becoming increasingly keratinised as they move to the skin surface. Keratinocytes adhere because of desmosome complexes attached to the cell membranes. |
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langerhan cells are what |
monocytes within the epidermis that recognise and process small molecules penetrating the skin surface. These antigen-presenting cells are identified in tissue sections by characteristic surface markers. |
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what cells in the basal layer of the epidermis protect against UV radiation |
Melanocytes in the basal layer protect the skin from ultraviolet radiation |
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epidermis layers |
come lets get sun burnt Stratum aka layer: Corneum Lucidum Granulosum Spinosum Basale between the basale stratum aka the basal layer and the dermis below it is the BASEMENT MEMBRANE |
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the basement membrane is attached to cells in the basal layer aka stratum basale via |
hemidesmosomes |
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Desmosomes make and break as |
keratinocytes move from basal layer to surface |
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The dermis supports the epidermis by providing it with |
nutrients and toughness |
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the dermis is mainly made up of |
collagen, with elastic fibres, ground substance, nerves, blood vessels and cellular infiltrations. |
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what is the name of the area just below the epidermis basement membrane |
The papillary dermis is the upper portion beneath the epidermis, characterised by thin haphazardly arranged collagen fibres, thin elastic fibres and ground substance. The lower portion is the reticular dermis, composed of coarse elastic fibres and thick collagen bundles parallel to the skin surface. |
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below the epidermis and dermis is the |
subcutaneous tissue |
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subcutaneous tissue is made up of |
lobules of adipose cells, which contain fat. These are surrounded by connective tissue, larger blood vessels and nerves. |
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within the skin BVs can be found in the |
dermis and subcutaneous tissue |
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skin appendages include |
Eccrine sweat apparatus Pilosebaceous structures Apocrine glands Nails |
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Eccrine sweat glands produce |
a hypotonic solution of water, sodium chloride, urea, ammonia and uric acid |
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eccrine sweat glands are most on the |
palms, soles, axillae and forehead and are absent on the lips, labia minora, glans penis and prepuce |
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eccrine sweat glands are found in what layer of the skin |
dermis |
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eccrine sweat glands is controlled by |
hypothalamus |
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Sweat is produced in response to |
exercise, high temperature (internal or environmental), spicy food, emotional stress and sometimes spontaneously It reaches the skin surface via a coiled duct. |
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Pilosebaceous structures produce |
terminal hair on the scalp and vellus hair on the body surface (short, thin, light coloured). |
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what helps erect hair |
Smooth muscles (arrector pili) cause erection of the hairs on exposure to cold or fear (goose bumps). |
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hair growth cycle includes |
growth phase (anagen) that lasts several years; a short involutional phase (catagen); and a resting phase that lasts for several months (telogen). Anagen hairs have a pointed tip and telogen hairs have a clubbed or bulbous tip. |
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Hair colour depends on |
the amount of melanin within the cortex during anagen dark hair has more eumelanin melanosomes; fair hair fewer with more lamellated phaeomelanin; red hair has erythromelanin; grey/white hair very few melanocytes. |
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Sebaceous glands produce |
sebum |
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sebaceous glands are most concentrated on |
scalp & face where circulating androgens induce increased secretion at puberty. |
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Sebum is secreted into the hair follicle except it in the labia, prepuce, nipple and areola, where it is secreted directly onto the skin surface. true/false |
true |
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Apocrine glands are found in |
axillae and perianal regions and become active after puberty They produce a thick secretion that rapidly becomes colonised by bacteria resulting in characteristic body odour. The ducts open into the pilosebaceous follicle |
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The nail plate is a specialised form of |
stratum corneum growing from keratinocytes in the matrix. |
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whats the acid mantle |
Skin has an average pH value of 5.5, creating the acid mantle |
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the acidity of skin is the result of |
acidic substances such as amino acids, lactic acid and fatty acids in perspiration, sebum and the hormones There are resident protective microflora (bacteria and yeasts) but the acid mantle repels pathogenic microorganisms and reduces body odour |
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skin color features |
varies from ‘white’ (absence of pigmentation) to ‘black’ (densely melanized). The colour depends on the quantity and depth of melanin and other chromophores. |
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skin colors |
Oxidised haemoglobin: red Deoxidised haemoglobin: blue Haemosiderin: red-brown Carotene: orange-yellow Bilirubin bound to elastin: green-yellow Dermal exogenous pigment: Tattoos, makeup, drugs, metallic compounds |
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he thickness and quality of keratinocytes and dermal components may also affect skin colour. e.g. |
A thick layer of horny cells can appear white (psoriasis), yellow (seborrhoeic dermatitis), dirty-brown (ichthyosis) or black (eschar). Inflammatory infiltrates may result in plaques that are yellow-brown (granulomata), violaceous (lichen planus) or scarlet (psoriasis). |
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melanin features |
The pigment melanin is formed by the action of tyrosinase on dopamine metabolites in melanosomes. Melanosomes are specialised pigment granules in the cytoplasm of melanocytes. Most skins produce eumelanin predominantly, but the melanin in red-headed celts is phaeomelanin. |
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The amount of melanin depends on: |
Genetic factors: ethnicity/phototype. Active melanogenesis. |
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There are melanocytes in the normal skin of all races. However, dark-skinned people produce more melanin, and it is distributed to keratinocytes throughout the epidermis. true/false |
true |
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The more superficial the pigment, the more effective the protection it provides against |
damage caused by ultraviolet radiation. Albinos have inactive melanocytes. |
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Melanin is found in the dermis in some melanocytic naevi (moles) and as a result of inflammation affecting the level of the basement membrane (postinflammatory pigmentation). true/false |
true |
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Melanin pigmentation is promoted by: |
Ultraviolet radiation Hormones (MSH, ACTH, androgens, oestrogens, progesterones) Inflammation Friction It may be reduced by Melatonin Corticosteroids. |
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hx taking for derm. key aspects |
Site or sites affected by the dermatosis. Its time course. Symptoms and functional problems. Exacerbating and relieving factors. Other health concerns and medications e.g. age, job, mhx, meds, gender, enviro influences, PCOMPLAINT = single/multiple/generalised; site, what bothers the px; sxs mhx = atopic conditions; diabetes; HTN; dyslipidemia (may impact tx) fhx = eczema, psoriasis, skin caner, autimmune skin probs and CTDs meds, allergies, shx |
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characterising a skin lesion |
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skin lesion distributions are many e.g. |
acral dermatomal extensor flexural follicular morbilliform koebnerised photosensitive pressure areas symmetrical truncal unilateral |
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what does acral distribution for a skin lesion look like |
affects distal portions of limbs (hand, foot) and head (ears, nose) |
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acral distribution photo |
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dermatomal skin lesions have what sort of distribution |
corresponding with a nerve root distribution |
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dermatomal skin lesion |
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extensor distribution effects the extensor areas of the limbs |
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flexural distributions involve what part of the skin |
skin flexures (body folds) aka intertriginous |
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flexure distribution |
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follicular distribution arise from |
hair FOLLICLES these may be grouped into confluent plaques |
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mobilliform distribution refers to |
generalised universal distribution may be mild/severe, scattered/diffuse |
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morbilliform distribution |
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koebnerised distribution refers to |
arising in a wound or scar the koebner phenomenon refers to the tendency of several skin conditions to affect areas subjected to injury esp psoriasis, lichen planus and vitiligo |
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koebnerised distribution |
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photosensitive distribution |
Favouring sun exposed areas. Does not affect skin that is always covered by clothing. Head & neck: spares eyelids, depth of wrinkles & furrows, areas shadowed by hair, nose & chin. Typically involves "v" of neck. Backs of hands: spares finger webs. More severe on proximal than distal phalanges. Forearms: extensor rather than flexor. Feet: dorsal surface, sparing areas covered by footwear. Lower legs: may affect extensor and/or flexor surfaces. Trunk: rarely affected |
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photosensitive distribution |
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Pressure areas affects |
areas regularly prone to injury from pressure at rest. Tops of the ears when sleeping. Buttocks when sitting.Heels when lying |
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pressure area distribution |
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symmetrical distribution of a skin lesion affects the same side on both sides of the body |
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truncal distribution of a skin lesion favours the trunk and rarely affects the limbs |
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unilateral distribution of a skin lesions tend to affect wholly/predominantly one side of the body |
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skin lesions are often grouped together. The pattern or shape may help in diagnosis as many skin conditions have characteristic configuration. e.g. |
annular discoid gyrate linear reticulated target lesion |
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annular skin lesion are grouped in a circle. multiple rings are polycyclic |
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discoid skin lesions are round (coin-shaped) lesions. aka nummular |
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a gyrate rash appears to whirling in a circle or spiral |
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a linear rash is like a straight line rash like in a scratch true/false |
true |
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reticulated rash resembles a |
net |
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target lesions have what |
concentric rings like a dartboard aka IRIS lesion |
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target lesion |
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