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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.

Functions of the skin include

barrier function, maintenance of fluid balance, regulation of body temperature, vitamin D synthesis and social communication.

the thinnest sites of skin are the

eyelids and scrotum

the thickest sites of skin are the

soles and palms

Skin is made up of


Basement membrane zone


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.

epidermis is a dynamic structure acting as a

semi-permeable barrier

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)

the surface ie outter most layer, of the epidermis is the

stratum corneum

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.

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.

what cells in the basal layer of the epidermis protect against UV radiation

Melanocytes in the basal layer protect the skin from ultraviolet radiation

epidermis layers

come lets get sun burnt

Stratum aka layer:






between the basale stratum aka the basal layer and the dermis below it is the BASEMENT MEMBRANE

the basement membrane is attached to cells in the basal layer aka stratum basale via


Desmosomes make and break as

keratinocytes move from basal layer to surface

The dermis supports the epidermis by providing it with

nutrients and toughness

the dermis is mainly made up of

collagen, with elastic fibres, ground substance, nerves, blood vessels and cellular infiltrations.

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.

below the epidermis and dermis is the

subcutaneous tissue

subcutaneous tissue is made up of

lobules of adipose cells, which contain fat. These are surrounded by connective tissue, larger blood vessels and nerves.

within the skin BVs can be found in the

dermis and subcutaneous tissue

skin appendages include

Eccrine sweat apparatus

Pilosebaceous structures

Apocrine glands


Eccrine sweat glands produce

a hypotonic solution of water, sodium chloride, urea, ammonia and uric acid

eccrine sweat glands are most on the

palms, soles, axillae and forehead and are absent on the lips, labia minora, glans penis and prepuce

eccrine sweat glands are found in what layer of the skin


eccrine sweat glands is controlled by


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.

Pilosebaceous structures produce

terminal hair on the scalp and vellus hair on the body surface (short, thin, light coloured).

what helps erect hair

Smooth muscles (arrector pili) cause erection of the hairs on exposure to cold or fear (goose bumps).

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.

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.

Sebaceous glands produce


sebaceous glands are most concentrated on

scalp & face where circulating androgens induce increased secretion at puberty.

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.



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

The nail plate is a specialised form of

stratum corneum growing from keratinocytes in the matrix.

whats the acid mantle

Skin has an average pH value of 5.5, creating the acid mantle

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

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.

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

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).

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.

The amount of melanin depends on:

Genetic factors: ethnicity/phototype.

Active melanogenesis.

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.



The more superficial the pigment, the more effective the protection it provides against

damage caused by ultraviolet radiation. Albinos have inactive melanocytes.

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).



Melanin pigmentation is promoted by:

Ultraviolet radiation

Hormones (MSH, ACTH, androgens, oestrogens, progesterones)



It may be reduced by



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

characterising a skin lesion

  • Site & size of a skin lesion.
  • Distribution of skin eruption.
  • Configuration (shape) of skin lesions.
  • Morphology of primary skin lesion.
  • Secondary changes.

skin lesion distributions are many e.g.









pressure areas




what does acral distribution for a skin lesion look like

affects distal portions of limbs (hand, foot) and head (ears, nose)

acral distribution photo

dermatomal skin lesions have what sort of distribution

corresponding with a nerve root distribution

dermatomal skin lesion

extensor distribution effects the extensor areas of the limbs

flexural distributions involve what part of the skin

skin flexures (body folds) aka intertriginous

flexure distribution

follicular distribution arise from


these may be grouped into confluent plaques

mobilliform distribution refers to

generalised universal distribution

may be mild/severe, scattered/diffuse

morbilliform distribution

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

koebnerised distribution

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

photosensitive distribution

Pressure areas affects

areas regularly prone to injury from pressure at rest.

Tops of the ears when sleeping.

Buttocks when sitting.Heels when lying

pressure area distribution

symmetrical distribution of a skin lesion affects the same side on both sides of the body

truncal distribution of a skin lesion favours the trunk and rarely affects the limbs

unilateral distribution of a skin lesions tend to affect wholly/predominantly one side of the body

skin lesions are often grouped together. The pattern or shape may help in diagnosis as many skin conditions have characteristic configuration.







target lesion

annular skin lesion are grouped in a circle. multiple rings are polycyclic

discoid skin lesions are round (coin-shaped) lesions. aka nummular

a gyrate rash appears to whirling in a circle or spiral

a linear rash is like a straight line rash like in a scratch true/false



reticulated rash resembles a



target lesions have what

concentric rings like a dartboard aka IRIS lesion

target lesion