Flashcards in WK 1- Skin, Hair and Nails Deck (70):
1
What are some functions of the skin
-Mechanical barrier
-Chemical barrier
-Defence against micro-organisms
-Immunological barrier
-Endocrine organ
-Defence against UV light
-Thermoregulation
-Sensory organ
2
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
3
What is the most common cell of the epidermis
Keratinocyte
4
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
5
What are the 3 non-keratinocyte cells of the epidermis
1. Melanocytes, 2. Langerhans cells, 3. Merkel Cells
6
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
7
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
8
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
9
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
10
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
11
What are the layers of the dermis
Reticular (thicker lower layer) and Papillary (thinner upper layer)
12
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
13
What is the hypodermis- what is it composed of
Subcutaneous tissue underlying the dermis
-composed of adipose cells
14
What is the role of the hypodermis
-aid in insulating the body and allow mobility
15
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
16
What are the 3 types of glands in the skin
Sebaceous glands, Aporcrine glands and Eccrine glands
17
What is the function of sebaceous glands
-greatest density on face and scalp- associated with hair follicles
-release sebum
18
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
19
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
20
What is the function of eccrine sweat glands
-release sweat, least abundant on the back
21
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
22
What is the hyponychium
white area at tip of nail that prevents bacteria entering the nail bed
23
What is the onychocorneal band
distal, white band that marks the most distal firm attachment of the nail plate to the nail bed
24
How long do fingernails take to completely regenerate
12-18 months
25
What are the 3 stages of the hair cycle
Anagen, catagen and telogen
26
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
27
What occurs in catagen
the keratinocytes and melanocytes undergo programmed death
-lasts less than 2 weeks
28
What occurs in telogen
resting stage, telogen hair has a club shaped proximal end
-lasts around 3 months
29
What is glabrous skin
glabrous skin includes the palms, soles and portions of the genitalia -> no hair follicles
30
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)
31
What is koebner phenomenon
aka isomorphic phenomenon localisation of a non-infective skin disorder to area of trauma eg. Psoriasis, atopic dermatitis
32
What is dariers sign
rubbing of an area of mastocytosis (bunch of mast cells sitting together) causes an intensive uriticarial reaction
33
What is an abscess
Is collection of pus in a cavity greater then 1cm in diameter
34
What is angioedema
Diffuse swelling of oedema which extends to the subcutaneous tissue
35
What is a bulla
Is a circumscribed elevation of skin over 0.5 cm and containing fluid -eg. Impetigo
36
What is a burrow
Is a linear of curvilinear papule caused by a burrowing mite e.g. scabies , arrows point to scabies
37
What does central clearing mean
Rash with a normal central area
38
What is a keloid
Very raised and erythematous scar
39
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
40
What is dysaesthesia
Tingling, burning, numbness
41
What is ecchymosis
A larger extravasations of blood into the skin
42
What is erythroderma
Rash involving at least 90% of skin surface
43
What is is eschar
Thick crust over an ulcer or erosion
44
What is excoriation
Superficial loss of epidermis (ulcer/erosion) from scratching or picking, therefore often linear and covered by crust eg. Scabies or prurigo
45
What is impetiginised
Covered in crust, pustules often weeping
46
What is lichenification
Thickening of epidermis usually due to friction
47
What is livedo
Purple lace-like or reticulated lesion usually on lower legs
48
What is keratosis
Is a horn like thickening of the skin e.g. solar keratosis
49
What is a macule
Small flat lesion of altered colour or texture
Eg. Lentigo simplex
50
What is a nodule
Raised firm ovoid lesion greater than 0.5cm in width and depth
eg. Nodular keloid scar
51
What is a micropapule
Raised lesion of 1-2mm in diameter
52
What is a papule
Small raised solid lesion less than 0.5mm
eg. Molluscum contagiosum
-can be described by their surface contours
53
What is a papulosquamous
Raised papules on a background of scale and redness
54
What is a plaque
Large raised lesion greater than 2cm in diameter but without substantial depth eg. psoriasis
55
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
56
What is a papilloma
Nipple like mass projecting from the skin e.g. a skin tag
57
What is petechiae
Are pinhead sized macules of blood in the skin e.g. Meningococcal disease
58
What does reticulated mean
lace like
59
What is a sinus
Cavity or channel which permits the escape of fluid or pus.eg Pilonidal sinus
60
What is a stria
Streak like, linear, atrophic, pink, purple or white lesion of the skin due to changes in the connective tissue
61
What does serpiginous mean
Edge of lesion is wavy
62
What does targetoid mean
Rash that looks like a bulls eye
63
What is Telangiectasis
Erythematous, fine linear lesion composed of capillaries produced by telangiectasia- visible dilastion of a small blood vessel
eg. Spider Angioma
64
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
65
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
66
What does verrucous mean
Very hyperkeratotic- similar to a wart
67
What is a vesicle
Small fluid filled lesion that is less than 0.5mm in diameter eg. Chicken pox
68
What does variegated mean
Multi-coloured
69
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
70