WK 1- Skin, Hair and Nails Flashcards Preview

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Flashcards in WK 1- Skin, Hair and Nails Deck (70):

What are some functions of the skin

-Mechanical barrier
-Chemical barrier
-Defence against micro-organisms
-Immunological barrier
-Endocrine organ
-Defence against UV light
-Sensory organ


What are the 5 main layers of the epidermis

Moving from top layer to bottom layer
5. Stratum Corneum, 4. Stratum Lucidum, 3. Stratum Granulosum
2. Stratum Spinosum, 1. Stratum Germinativum/basale


What is the most common cell of the epidermis



How thick is the epidermis in the face vs feet
-why is there a change

Approximately 0.1 (face) to 1mm thick (sole of feet)
-Thicker in feet to provide more protection, thinner in face to allow for mobility and sensation


What are the 3 non-keratinocyte cells of the epidermis

1. Melanocytes, 2. Langerhans cells, 3. Merkel Cells


What is the role of melanocytes

-Melanocytes are pigment cells and provide colour to the skin/hair/eyes
-Melanocytes screen out UV radiation
-All people have the same amount of melanocytes though darker skinned individuals the melanocytes produce more melanaomes, which are broken down less rapidly then caucasoids people


Where are melanocytes found and how is melanin transferred

located in the stratum basale, dermis and hair follicles→ most numerous on face and exposed areas of skin
-melanin is contained in melanosomes and then transferred to keratinocytes via dendritic processes


What is the role of langerhans cells

Langerhans cells (aka Ag presenting cells) have long dendritic processes that radiate throughout the epidermis- collect Ag- and then migrate through the epidermis and dermis into the lymph nodes where they present to T cells


What is the role of Merkel Cells

These are sensory mechanoreceptors--> located in stratum basale but only in thick skin
-closely associated with free nerve endings of cutaneous nerves


What is the dermis- what is it composed of

Layer below epidermis that is made from tough supportive connective tissue matrix predominately made of collagen
-elastic connective tissue is the other main type of fibrous connective tissue in the dermis and accounts for 4% dry weight of dermis
-returns skin to normal configuration after stretching


What are the layers of the dermis

Reticular (thicker lower layer) and Papillary (thinner upper layer)


What are the 4 cells in the dermis

Fibroblasts: synthesis and degradation of CT
Macrophages: phagocytic cells
Mast cells: secretory cells
Lymphocytes: small number collect around blood vessels in normal skin


What is the hypodermis- what is it composed of

Subcutaneous tissue underlying the dermis
-composed of adipose cells


What is the role of the hypodermis

-aid in insulating the body and allow mobility


What are the main sensory receptors of the skin

1. free nerve endings (merkel cells) that allow you to determine pressure on skin→ signals can be relayed to nerve fibres
2. Encapsulated receptors→ pacinian and meissners corpuscle
3. Pertichrial free nerve endings→ sit at the bottom of hair cells and relay touch


What are the 3 types of glands in the skin

Sebaceous glands, Aporcrine glands and Eccrine glands


What is the function of sebaceous glands

-greatest density on face and scalp- associated with hair follicles
-release sebum


What is sebum- what canal is it secreted through

a complex mixture of lipids and secreted onto the skin through the pilosebaceous canal
-sebum has an antibacterial and antifungal action and contributes to normal barrier function of skin


When are sebaceous glands most active - what is the connection to acne

sebaceous gland activity is high at birth but declines to almost nothing between 2 and 6 years
-between 7 and 20 sebum production is high and then will decline at the age of 20
-males on average have higher rates than females meaning males have higher rates of acne


What is the function of eccrine sweat glands

-release sweat, least abundant on the back


What is the function of apocrine sweat glands

-large gland that discharge into hair follicles rather than directly onto the surface (unlike sebaceous glands)
-no odor when first secreted but produces pheromones


What is the hyponychium

white area at tip of nail that prevents bacteria entering the nail bed


What is the onychocorneal band

distal, white band that marks the most distal firm attachment of the nail plate to the nail bed


How long do fingernails take to completely regenerate

12-18 months


What are the 3 stages of the hair cycle

Anagen, catagen and telogen


What occurs in anagen/how long does it last

growing phase→ follicle penetrates deeply into the hypodermis and keratinocytes in the follicular bulb proliferate to form the hair shaft and melanocytes responsible for the pigmentation of the hair are dispersed among these keratinocytes
-lasts between 2-6 years


What occurs in catagen

the keratinocytes and melanocytes undergo programmed death
-lasts less than 2 weeks


What occurs in telogen

resting stage, telogen hair has a club shaped proximal end
-lasts around 3 months


What is glabrous skin

glabrous skin includes the palms, soles and portions of the genitalia -> no hair follicles


What is nikolsky sign

shearing stress on the skin causes separation of the skin along a horizontal plane→ results in traumatic bulla and occurs in fragile skin (autoimmune)


What is koebner phenomenon

aka isomorphic phenomenon localisation of a non-infective skin disorder to area of trauma eg. Psoriasis, atopic dermatitis


What is dariers sign

rubbing of an area of mastocytosis (bunch of mast cells sitting together) causes an intensive uriticarial reaction


What is an abscess

Is collection of pus in a cavity greater then 1cm in diameter


What is angioedema

Diffuse swelling of oedema which extends to the subcutaneous tissue


What is a bulla

Is a circumscribed elevation of skin over 0.5 cm and containing fluid -eg. Impetigo


What is a burrow

Is a linear of curvilinear papule caused by a burrowing mite e.g. scabies , arrows point to scabies


What does central clearing mean

Rash with a normal central area


What is a keloid

Very raised and erythematous scar


What is a comedone

Is a plug of keratin and sebum wedged in a dilate pilosebaceous orifice. Open comedones are blackheads. The follicle opening of a closed comedone is nearly closed over by skin so it looks like a pinhead sized , ivory coloured papule


What is dysaesthesia

Tingling, burning, numbness


What is ecchymosis

A larger extravasations of blood into the skin


What is erythroderma

Rash involving at least 90% of skin surface


What is is eschar

Thick crust over an ulcer or erosion


What is excoriation

Superficial loss of epidermis (ulcer/erosion) from scratching or picking, therefore often linear and covered by crust eg. Scabies or prurigo


What is impetiginised

Covered in crust, pustules often weeping


What is lichenification

Thickening of epidermis usually due to friction


What is livedo

Purple lace-like or reticulated lesion usually on lower legs


What is keratosis

Is a horn like thickening of the skin e.g. solar keratosis


What is a macule

Small flat lesion of altered colour or texture
Eg. Lentigo simplex


What is a nodule

Raised firm ovoid lesion greater than 0.5cm in width and depth
eg. Nodular keloid scar


What is a micropapule

Raised lesion of 1-2mm in diameter


What is a papule

Small raised solid lesion less than 0.5mm
eg. Molluscum contagiosum
-can be described by their surface contours


What is a papulosquamous

Raised papules on a background of scale and redness


What is a plaque

Large raised lesion greater than 2cm in diameter but without substantial depth eg. psoriasis


What is purpura

Describes a large macule or papule of blood in the skin. These do not blanch if a glass slide is pushed against them.eg Suction injury and further left Henoch-Schonlein purpura


What is a papilloma

Nipple like mass projecting from the skin e.g. a skin tag


What is petechiae

Are pinhead sized macules of blood in the skin e.g. Meningococcal disease


What does reticulated mean

lace like


What is a sinus

Cavity or channel which permits the escape of fluid or pus.eg Pilonidal sinus


What is a stria

Streak like, linear, atrophic, pink, purple or white lesion of the skin due to changes in the connective tissue


What does serpiginous mean

Edge of lesion is wavy


What does targetoid mean

Rash that looks like a bulls eye


What is Telangiectasis

Erythematous, fine linear lesion composed of capillaries produced by telangiectasia- visible dilastion of a small blood vessel
eg. Spider Angioma


What is a tumour

Enlargement of the tissues by normal or pathological material or cells that form a mass more then 1 cm in diameter


What is an ulcer

Is an area of the skin where the whole of the epidermis and at least part of the dermis has been lost. e.g. SCC


What does verrucous mean

Very hyperkeratotic- similar to a wart


What is a vesicle

Small fluid filled lesion that is less than 0.5mm in diameter eg. Chicken pox


What does variegated mean



What is a wheal

Is an elevated white compressible, short-lived area produced
by dermal oedema. It is often surrounded by red axon
mediated flare


What does sclerotic mean

scar like