Y2 Dermatology > Skin Structure and Function > Flashcards

Skin Structure and Function Flashcards

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1
Q

Embryological origin of the epidermis

A

Ectoderm

Think Epidermis Ectoderm

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2
Q

Embryological origin of the dermis

A

Mesoderm

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3
Q

Pattern of growth of skin development follows _______ _____ and rashes which may follow this pattern can be a sign of congenital developmental issues

A

Blaschko’s lines

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4
Q

Appendages of the skin may include (4)

A

Nails
Hair
Mucosae
Glands

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5
Q

The epidermis is made of what form of epithelium?

A

Stratifies squamous epithelium

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6
Q

4 main layers of epidermis, in order from top to bottom

A
  1. Keratin layer
  2. Granular layer
  3. Prickle cell layer
  4. Basal cell layer
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7
Q

3 cell types which do not originate from the epidermis, but are found there?

A
  1. Melanocytes
  2. Langerhans cells
  3. Merkel cells
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8
Q

4 Features of the Basal Cell layer

A
  1. One cell thick
  2. Small cuboidal cells
  3. Lots of intermediate keratin filaments
  4. Very metabolically active
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9
Q

4 Features of the Prickle Cell layer

A
  1. Large polyhedral cells
  2. Lots of connecting desmosomes
  3. Intermediate filaments connecting the desmosomes
  4. cells that evolve and produce proteins
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10
Q

4 Features of the Granular Cell layer

A
  1. 2-3 layers of flatter cells
  2. keratinohyaline granules containing filaggrin and involucrin
  3. high lipid content
  4. cell nuclei are lost here
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11
Q

4 Features of the Keratin layer

A
  1. lots of overlapping non-nucleated cells
  2. Waterproof
  3. 80% keratin and filaggrin
  4. insensitive to pain
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12
Q

Guess the cell type: These cells migrate from the neural crest

A

Melanocytes

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13
Q

Within which layers of the epidermis are melanocytes found?

A

from the basal layer and above

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14
Q

What type of cells are melanocytes?

A

pigment producing dendritic cells

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15
Q

What is the role of melanosomes found within melanocytes?

A

convert tyrosine to melanin

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16
Q

What are the two forms of melanin?

A
  1. Eumelanin

2. Phaeomelanin

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17
Q

Describe eumelanin

A

brown or black melanin with protective function. it is found in hair

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18
Q

Describe phaeomelanin

A

red or yellow melanin

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19
Q

How do melanocytes protect the keratinocytes?

A

The melanosomes migrate to the dendrites of the melanocyte and provide a protective kap over the nucleus of the keratinocyte.

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20
Q

What is a mole?

A

A nest of melanocytes

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21
Q

Where are merkel cells found?

A

The basal layer between keratinocytes and nerve fibres; they are ubiquitous

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22
Q

Function of Merkel Cells

A

Mechanoreceptors

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23
Q

What is the origin of Langerhans cells?

A

Bone marrow

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24
Q

Where are Langerhans cells found?

A

From the Prickle cell layer and above, the dermis and the lymph nodes

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25
Function of Langerhans cells
Aid the skin immune system by acting as APCs
26
**What feature is unique to Langerhans cells?**
**Racket organelles which contain birbeck granules** | This is a common exam question
27
How does the hair follicle develop?
Initially grows through an epidermal component and then down into the dermis to develop a dermal papilla
28
Where does pigmentation come from in hair?
melanocytes above the dermal papilla
29
Where does the hair follicle develop? (embryologically)
ectoderm
30
Phases of hair growth (3)
Anagen Catagen Telogen
31
Anagen phase of hair growth
growth phase
32
Catagen phase of hair growth
involuting phase
33
Telogen phase of hair growth
resting phase
34
Hormones which affect hair growth patterns (2)
thyroxine, androgens
35
What contributes to male pattern baldness?
androgen hormone production
36
What is hirsutism?
the abnormal growth of hair in females. Hair grows in areas associated with androgen receptors
37
What may cause hirsutism?
a tumour
38
What is alopecia (in brief)?
autoimmune hair loss
39
What are the 3 parts of the nail plate?
ventral, intermediate, dorsal
40
What is the difference in skin growth in psoriasis?
accelerated growth means a normally 28 day journey takes 4-5 days
41
What defect occurs due to psoriasis?
defective granular cells with a loss of genetic control and sheets of skin which do not slough off easily
42
What does HPV cause in the skin?
warts
43
What cells do warts affect?
keratinocytes
44
What is the basic process underlying vitiligo?
melanocytes are attacked by the immune system
45
What is a potential treatment of vitiligo?
UV treatment to kill off the immune cells in the skin
46
What is the downside of the treatment of vitiligo using UV light?
may cause malignant melanoma
47
Basic process underlying Nelson's Syndrome?
Cushing's patients who have undergone a bilateral adrenalectomy may have raised levels of ACTH which stimulates the production of melanin.
48
Origin of Langerhans cells
Mesenchymal origin in bone marrow
49
Where are Langerhans cells found?
prickle cell, dermis, lymph nodes
50
****Found specifically in Langerhans cells****
Racket organelles - Birbeck granules
51
****Birbeck granules****
Racket shaped organells in langerhans cells ****
52
Where are merkel cells found?
in the basal layer between keratinocytes and nerve fibres
53
Skin mechanoreceptors
Merkel cells
54
Merkel cell cancer?
rare but very malignant form of cancer caused by a viral infection - no cure and usually found in the elderly
55
Hair follicle is made up of...
specialised keratins with an adjacent sebaceous glands and a dermal papilla
56
The development of a hair follicle
originates in the ectoderm and then transfers down into the mesoderm where the papilla and vasculature form
57
Phases of growth of hair (3)
Anagen, Catagen, Telogen
58
Anagen
growing
59
Catagen
involuting
60
Telogen
resting phase
61
hair growth is influenced by hormones such as (2)
androgens and thyroxine
62
Hirsutism
hair growth in the androgen receptor areas in females, which may be due to an androgen secreting tumour
63
Alopecia
An autoimmune hair loss
64
What is the dermo-epidermal junction?
the interface between the epidermis and the dermis
65
Bullous pemphigoid is common in which age group?
the elderly
66
What happens in bullous pemphigoid?
essential anchoring proteins fail causing in a separation of the dermis and the epidermis resulting in blisters
67
Common conditions associated with the development of bullous pemphigoid?
PD, Stroke and IgG antibodies against the junction
68
Defective protein in Epidermylosis Bullosa
DE17
69
3 Layers in the dermo-epidermal junction
lamina lucida, lamina densa, sub-lamina densa
70
Ground substance in the dermis
Hyuloronic acid
71
Cells found in the dermis
fibroblasts, macrophages, mast cells, lymphocytes, langerhans cells
72
Cause of angiomas
overgrowth of the superficial and deep plexuses of the vasculature supplying the dermis
73
How may angiomas be treated
b-blockers
74
2 types of corpuscles found in the skin
Meissner's, Pancinian
75
Meissner's corpuscles
special somatosensory receptors sensitive to vibrations
76
Pancinian corpuscles
special somatosensory receptors sensitive to pressure
77
Neurofibromatosis
a rare genetic overgrowth of the nerve endings in the skin which may also cause brain tumours.
78
Key features of sebacceous glands (3)
1. widely distributed with holocrine secretion opening into the piliary canal 2. largest on chest and face 3. control moisture loss and protect against fungal infection
79
Key features of appocrine glands (3)
1. develop as part of the pilosebacceous unit 2. mostly in axillae and perineum 3. androgen dependent producing oily fluids (adolescence) Appocrine Adolescence
80
Key features of eccrine glands (4)
1. found everywhere but mostly on palms, soles and axillae 2. sympathetic cholinergic supply 3. mental, thermal and gustatory stimulation 4. cooling by evaporation - sweat Eccrine Everywhere
81
How does the skin produce vitamin D?
UV light converts cholecalciferol into vitamin D
82
Important structural proteins found in the keratin layer (3)
filaggrin, involucrin, keratin
Y2 Dermatology
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