Skin Structure and Function Flashcards
(127 cards)
1
Q
What type of epithelium is in the epidermis
A
stratified squamous epithelium
2
Q
Which germ layer does epidermis come from
A
ectoderm
3
Q
Which germ layer does dermis come from
A
mesoderm
4
Q
Where do melanocytes originate from
A
neural crest
5
Q
Foetal skin development by 4 weeks
A
Periderm, basal layer, dermis
6
Q
Foetal skin development by 16 weeks
A
Keratin layer, granular layer, prickle cell layer, basal layer, dermis
7
Q
Foetal skin development by 26 weeks
A
Keratin layer, granular layer, prickle cell layer, basal layer, dermis, sebaceous glands, arrector pili, hair follicles, melanocytes
8
Q
Layers of epidermis superficial to deep
A
Keratin layer (stratum corneum), granular layer (stratum granulosum), prickle cell layer (stratum spinosum), basal layer (stratum basale)
9
Q
what is the extra layer of the epidermis in thick skin like palms and soles of feet called?
A
stratum lucidum
10
Q
Developmental growth pattern of skin
A
Blaschko’s lines
11
Q
Sub-cutis is predominantly ____
A
fat
12
Q
How thick is the epidermis
A
1.5mm
13
Q
What type of cell makes up 95% of the epidermis
A
keratinocytes
14
Q
Where do keratinocytes originate
A
basement membrane
15
Q
Palm and sole of foot histology features
A
thick keratin layer, no hair follicles
16
Q
How long do keratinocytes take to go from basement membrane up to top
A
28 days
17
Q
basal cell shape
A
cuboidal
18
Q
how thick is the basal layer usually
A
one cell thick
19
Q
how many layers of cells does the granular layer have
A
2-3
20
Q
which epidermal layer has lots of larger polyhedral cells and desmosomes
A
prickle cell layer
21
Q
which epithelial layer contains large keratohyalin granules?
A
granular layer
22
Q
what do large keratohyalin granules contain?
A
structural filaggrin and involucrin proteins
23
Q
which epithelial layer contains odland/lamellar bodies
A
granular layer
24
Q
the granular layer has a high lipid content, true or false
A
true
25
which epidermal layer is the origin of the "cornified envelope"
granular layer
26
in which skin layer are cell nuclei lost
granular layer
27
what makes up most of the keratin layer
keratinocytes
28
what is the insoluble cornified envelope
a highly insoluble and tough structure formed beneath the cell membrane during terminal differentiation of keratinocytes.
29
what does HPV infection of keratinocytes cause
warts
30
3 types of oral mucosa
masticatory, lining, specialised
31
masticatory mucosa
keratinised stratified squamous epithelium to deal with friction/pressure
32
lining mucosa
non-keratinised stratified squamous epithelium
33
specialised mucosa
tongue papillae, taste
34
ocular mucosa
lacrimal glands, eyelashes, sebaceous glands
35
main epidermal cells
keratinocytes, melanocytes, langerhans, merkel
36
where is melanin produced
melanosomes within the melanocytes
37
are melanocytes dendritic cells?
yes
38
what is the function of melanin caps?
protect the nuclear DNA in basal cells
39
what is the result of melanocytes clumping together?
freckles!
40
what are the two types of melanin?
eumelanin (brown/black pigment), pheomelanin (red/yellow pigment)
41
what happens in vitiligo?
autoimmune loss of melanocytes
42
vitiligo is an autoimmune disease, true or false
true
43
what happens in albinism?
genetic partial loss of pigment production
44
what happens in Nelson's syndrome?
melanin stimulating hormone (MSH) is produced in excess by the pituitary
(as well as other hormones).
It's a disorder characterized by abnormal hormone secretion, enlargement of the pituitary gland, and the development of adenomas
45
For healthy skin you need:
intact physical barrier, functioning immune system, adequate supply and drainage of blood, functioning venous return and lymphatic system, means of temperature regulation (capillary dilation/constriction, functioning sweat glands), normal sensory nerve function to warn us about injury, adequate nutrition.
46
what type of healing is there in surgical wounds
primary intention
47
which skin layer are odland bodies found in?
granular layer
48
where are Langerhans cells formed?
bone marrow
49
which skin layer are langerhans cells most prominent in?
prickle cell layer (but are found in all layers)
50
what do langerhans cells do?
pick up antigen in skin and circulate it to lymph nodes via lymphatic system
51
what are birbeck granules?
rod-shaped or "tennis racket" cytoplasmic organelles in epidermal langerhans cells
52
langerhans cells are antigen-presenting dendritic cells, true or false
true
53
where are merkel cells located
basal layer (amongst keratinocytes and nerve fibres)
54
Acute intermittent porphyria is due to impaired function of what
porphobilinogen deaminase
55
what type of mechanoreceptors are merkel cells
type 1
56
merkel cells are touch sensitive cells, true or false
true
57
merkel cell cancer is common, true or false
false, it is rare
58
3 phases of hair growth
anagen, catagen, telogen
59
Anagen phase of hair growth
growing
60
What happens in the catagen phase of hair growth
hair stops growing and becomes detached from the base of the follicle
club hairs form
61
Catagen phase of hair growth
involuting
62
Telogen phase of hair growth
resting.
falling out.
63
what is lanugo hair
in utero - soft, fine, covers foetus in womb
64
what is vellus hair
peach fuzz on face, arms, stomach, legs
65
what is terminal hair
hair on scalp, eyebrows, eyelashes. after puberty - beard, armpits, pubic hair, chest
66
where are langerhans cells formed
bone marrow
67
where are hemi-desmosomes found
dermo-epidermal junction
68
what is telogen effluvium
hair loss characterised by hair thinning or increases in hair shedding.
A change in hormone levels means all the hairs go into telogen at the same time
69
who might typically have telogen effluvium
- women
- postpartum
- can also happen in illness
70
what is virilisation
female develops male characteristics
71
causes of virilisation
- androgen-secreting tumours
- could just be bad luck
72
autoimmune hair loss
alopecia areata
73
who is more likely to get alopecia areata
people with certain autoimmune diseases such as psoriasis, thyroid disease, vitiligo, SLE
74
circular patches of hair loss
alopecia areata
75
what is subungual hyperkeratosis
build-up of keratin under nail
76
what condition is subungual hyperkeratosis associated with
psoriasis
77
what are the layers of the dermoepidermal junction
- lamina lucida
- lamina densa
- sub-lamina densa zone
78
main cells in the dermis
- FIBROBLASTS
- macrophages
- mast cells
also lymphocytes and langerhans cells
79
what fibres are in the dermis
collagen and elastin
80
what makes collagen and elastin
fibroblasts
81
ethnic differences in the dermis
dark skin - thicker dermis and more fibroblasts and more macrophages
82
what is photoaging caused by
exposure to UV radiation
83
where are horizontal plexuses (formed by blood vessels) found
in the dermis
84
does an angioma need treated? what can it be treated with?
no, it's benign and unlikely to cause any problems.
but can be treated with laser, topical beta blocker, or surgery if it's small
85
chronic lymphoedema
chronically enlarged lymphatic channels
86
treatment for chronic lymphoedema
- moisturisers
- treat dermatitis
- compression stockings to try move the fluid back up to the heart
87
nerves in the dermis
- free nerve endings (pain receptors)
- Pacinian corpuscles and Meissner's corpuscles
- autonomic nerve supply
88
which type of nerve looks like an onion
pacinian corpuscle
89
what is neurofibromatosis
genetic condition that causes tumours to grow along your nerves (neuromas)
90
3 main segments of hair follicle
- infundibulum
- isthmus
- hair bulb
91
which race has the fastest hair growth
asian
92
which race has the lowest hair density
african
93
which race has the most fragile hair
african
94
what is hirsutism
male pattern hair growth in a woman, e.g. beard
95
causes of hirsutism
- could be in the family
- polycystic ovary syndrome
- tumour secreting a hormone causing it in older patients
96
treatment of hirsutism
topical creams or could laser
97
are sebaceous glands active pre-puberty?
no
98
do apocrine glands form as part of the pilosebaceous unit
yes
99
which gland is responsible for body odour
apocrine
100
when do apocrine glands develop
at puberty
101
where are sebaceous glands NOT present
palm and sole skin
102
where on the body are Meissner corpuscles found
hairless skin (fingertips, eyelids)
103
which sensory receptors detect light touch, e.g. sensation of tshirt on skin when putting it on
Meissner corpuscles
104
where are free nerve endings located in the skin
basal layer of the epidermis
105
which parts of hair contain:
a) 'soft' keratin
b) 'hard' keratin
a) central medulla
b) outer cortex and cuticle
106
which region of the hair contains the keratin producing cells
matrix region
107
which sensory receptors are responsible for detecting vibration, and sensing deep touch/pressure
Pacinian corpuscles
108
where are eccrine glands found
whole body skin surface except the lips and genitals
109
what condition do overactive eccrine glands cause
hyperhidrosis
110
what is toxic epidermal necrolysis
life-threatening skin disorder. blistering and peeling of skin. majority are drug induced
111
conditions where the physical barrier of the skin has gone wrong
- steroid-sulphatase deficiency x-linked ichthyosis
- cumulative irritant hand dermatitis
- ulcer following compound fracture
112
what is ichthyosis
group of skin disorders that lead to dry, itchy skin that appears scaly, rough, and red
113
"fish-scale" skin
ichthyosis
114
sources of vit D
- UV light
- fish
115
tuberculoid leprosy features
raised edge
granulomas on histology
116
what is eczema herpeticum
skin infection caused by the herpes simplex virus (HSV).
(mostly in people who already have atopic dermatitis (i.e., eczema)
117
who is most likely to get eczema herpeticum
- infants and young children
- those with severe atopic dermatitis
118
what type of disease is chronic discoid erythematosus
autoimmune
(it's basically the skin version of sle, internal organs not affected)
119
what is dermatitis artefacta
a psychocutaneous disorder in which the patients consciously create lesions in skin, hair, nail, or mucosae to satisfy a psychological need, attract attention, or evade responsibility
120
what is a consequence of failure of the metabolic function of the skin
disordered thyroxine metabolism (because some T4 to T3 conversion happens in the skin)
121
which condition can spongiosis be seen on histology
eczema
122
what do hair follicles look like on histology
oval doughnut shapes
123
histological features of psoriasis
- thickened keratin layer
- parakeratosis (nuclei in the keratin layer)
- accumulation of inflammatory cells (particularly neutrophils) in the upper epidermis
- rete pegs
124
histology of sole of foot
- no hair follicles
- thick keratin layer
- prominent granular layer
- irregular DEJ (because more stress on feet??)
125
3 stages of wound healing
1. inflammation
2. proliferation
3. tissue remodelling
126
should slough be removed from the wound
yes, it has inhibitory effects on the healing ability of the wound and should be removed chemically or with physical debridement. larval therapy can also be used
127
which is more rapid, primary or secondary intention wound healing?
primary
