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Dermatology > Structure and Function 1 and 2 > Flashcards

Structure and Function 1 and 2 Flashcards

1
Q

What are the two layers of the skin? Which is external and which is internal? When do they come together?

A

Epidermis (external) and dermis (internal), they come together during embryo development

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2
Q

Which layer is thicker, the dermis or epidermis?

A

Dermis

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3
Q

What epithelial cell is the epidermis composed of?

A

Stratified squamous epithelium

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4
Q

What is the dermis composed of?

A

Leathery, fibrous connective tissue

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5
Q

Where is the epidermis embryologically derived from?

A

Ectoderm

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6
Q

How is the epidermis embryologically formed?

A

Forms a single layer periderm which gradually increases in the number of cells until they cast off

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7
Q

Where is the dermis embryologically derived from?

A

Mesoderm

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8
Q

Where is the mesoderm in relation to the ectoderm?

A

Below

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9
Q

In relation to skin development, what happens at 4 weeks?

A

The periderm, basal layer and dermis are formed

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10
Q

When does gastrulation occur?

A

Days 7-10

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11
Q

In relation to skin development, what happens at 16 weeks?

A

The layers of the epidermis are formed

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12
Q

In relation to skin development, what happens at 26 weeks?

A

Skin appendages are formed

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13
Q

What do Blascko’s lines show?

A

The developmental growth pattern of skin

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14
Q

Do Blascko’s lines follow vessels, nerves or lymphatics?

A

No

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15
Q

What does it indicate if Blascko’s lines show up on a child?

A

A congenital fault where something went wrong with the migration of cells during development

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16
Q

What makes up 95% of cells in the epidermis?

A

Keratinocytes

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17
Q

Describe the differentiation of cells in the epidermis?

A

Cells move upwards from the basal layer which allows continuous regeneration of the epidermis, with one cycle taking around 28 days

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18
Q

How many layers are there of the epidermis?

A

4

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19
Q

Give three examples of specialised cells found in the epidermis?

A

Melanocytes, Merkel cells, Langerhans cells

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20
Q

Are the contents of the epidermis consistent all over the body?

A

No, they vary depending on the site

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21
Q

How does the epidermis reversibly react to mechanical pressure?

A

Produces more keratin

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22
Q

What are three things which control epidermal cell turnover?

A

Growth factors, cell death and hormones

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23
Q

Control of epidermal cell turnover is lost in what diseases?

A

Psoriasis and skin cancer

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24
Q

How long does epidermal cell turnover take in psoriasis? Problems with differentiation in psoriasis lead to the loss of which epidermal layer?

A

4-5 days

No granular layer

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25
What are the layers of the epidermis from inner to outer?
- Basal cell - Prickle cell - Granular - Keratin
26
Which layer of the epidermis is made up essentially of stem cells?
Basal cell layer
27
Describe the basal cell layer?
Usually one cell thick, small and cuboidal with lots of intermediate filaments. It is highly metabolically active.
28
Describe the prickle cell layer?
Larger polyhedral cells which contain lots of desmosomes and intermediate filaments to hold the cells together
29
How many layers of cells does the granular layer have?
2-3 layers of flatter, granular cells
30
What are the two structural proteins found in the granular layer? What is their function?
Filaggrin and involucrin- important in protecting the water barrier
31
The water barrier of the epidermis is lost in what disease?
Eczema
32
What is the lipid content of the granular layer? | Are there nuclei present?
High lipid content | No nuclei
33
What cells is the keratin layer composted of?
Corneocytes
34
What are corneocytes?
Terminally differentiated keratinocytes
35
The keratin layer can also be known as what?
Stratum corneum
36
Describe the keratin layer?
80% keratin and filaggrin with lamellar granules releasing lipids to form a tight waterproof barrier
37
HPV infection of keratinocytes causes what?
Viral warts
38
Which layer of the epidermis looks like flat slabs?
Keratin
39
Apart from skin, what other structure can be implicated in skin disease?
Mucosal membranes
40
In the oral mucosa, which of the masticatory/lining mucosa is keratinised?
Masticatory
41
What three other cells can be found in the epidermis which are not keratinocytes?
- Melanocytes - Langerhans Cells - Merkel Cells
42
Are melanocytes found basal, supra basal or both?
Both
43
Are Langerhans cells found basal, supra basal or both?
Supra basal
44
Are Merkel cells found basal, supra basal or both?
Basal
45
Where are melanocytes embryologically derived from? When do they join up with the epidermis?
Derived from the neural crest, transfer to the epidermis in the first 3 months of foetal development
46
What type of cells are melanocytes?
Pigment producing dendritic cells
47
What are the specialised organelles found within melanocytes? What do they do?
Melanosomes- convert tyrosine into melanin
48
What colour is eumelanin?
Black/brown
49
What colour is phaeomelanin?
Red/yellow
50
What happens once melanin has absorbed light?
Melanin granules (full melanosomes) are transferred to adjacent keratinocytes to form a protective cap over the nucleus to protect the DNA and basal stem cells from UV light
51
What is vitiligo?
An autoimmune disease causing immune destruction of melanocytes
52
How can vitiligo be treated? What is the risk of this?
UV phototherapy to block the function of the immune cells which are destroying the melanocytes If the melanocytes are stimulated this can cause melanoma
53
What is albinism?
Genetic partial loss of pigment production
54
What is Nelson's Syndrome?
Melanin stimulating hormone is produced in excess by the pituitary gland, most likely because of a pituitary adenoma
55
What is a malignant melanoma?
A tumour of the melanocyte cell line
56
Where do Langerhans cells originate from?
Bone marrow
57
Where are Langerhans cells found?
Prickle cell layer of the epidermis as well as the dermis and lymph nodes
58
What is the function of Langerhans cells?
Antigen presenting cells- they pick up the antigen in the skin and then circulate it back to lymph nodes via the lymphatics
59
What is the specific racket organelle found in Langerhans cells known as? What is its function?
Birbeck granules- they have no known function
60
Where are Merkel cells found?
Basal, between keratinocytes and nerve fibres
61
What is the function of Merkel cells?
Mechanoreceptors forming a connection between the skin and brain
62
Where do Merkel cells originate from embryologically?
Mesoderm
63
What is Merkel cell cancer?
A neuroendocrine carcinoma which is rare and caused by a viral infection- there is no cure
64
Are hair follicles in the epidermis, dermis or both?
Both, the papilla is in the dermis
65
What gland is always associated with hair follicles?
Sebaceous glands
66
What always comes with a sebaceous gland?
A grease sac
67
Where does hair pigment come from?
Melanocytes above the dermal papilla
68
Where is hair embryologically derived from/
Ectoderm
69
What is the muscle which allows hairs to stand up known as?
Arrector pili muscle
70
What are the 3 stages of growth of hair follicles?
Anagen- growing Catagen- involuting Telogen- resting
71
What are the lengths of the three periods of growth of hair?
They vary, with the exception of catagen which always lasts 4 weeks
72
What hormones may influence hair growth?
Thyroxine, androgens
73
Is it normal for humans hairs to enter the stages of growth at the same time? What is it called if this occurs?
No- telogen effluvium
74
What is the most common cause of hair loss in humans? Is it reversible?
Telogen effluvium- yes it is reversible
75
What is alopecia areata?
Autoimmune hair loss condition where the follicles are attacked by the immune system
76
What is virilisation?
The development of male physical characteristics in a women or precociously in a boy due to excess androgens
77
What is hirsutism?
Secretion of excess androgens causing excessive male pattern hair growth in females
78
What is the growth rate of nails?
0.1mm/day
79
When do nails grow faster, winter or summer?
Summer
80
If a part of the nail is crumbly what does this mean/
There has been trauma at the matrix under the nail and loss of stem cells

Dermatology (15 decks)

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