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BRS > Dermatology 1 > Flashcards

Dermatology 1 Flashcards

1
Q

How is the skin embryologically formed?

A

Juxtaposition of the ectoderm (epidermis) and the mesoderm (dermis)

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2
Q

What happens in week 4 of development?

A

Epidermis forms from a single basal layer of cuboidal cells

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3
Q

What happens in week 5 of development?

A

Periderm develops along with the Vernix caseosa

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4
Q

What happens in week 11 of development?

A

Basal layer proliferates to from 4 more superficial strata

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5
Q

What happens in week 9-13 of development?

A

Hair follicles + lanugo hair form in the stratum germinatium

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6
Q

How do we get the formation of melanocytes?

A

Derived from neural crest to melanobasts and then differentiation and dorsal migration to epidermis, dermis and hair follicles to form melanocytes

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7
Q

When do melanocytes form?

A

Week 12-13

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8
Q

What else aside from melanocytes can melanoblasts form?

A

Melanocyte stem cells for replenishment

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9
Q

How are melanocytes regulated?

A

MC1R gene (Melanocortin 1 receptor) - regulates the quantity and quality of melanin produced

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10
Q

How does ACTH affect MC1R?

A

Upregulates MC1R expression

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11
Q

How does a-MSH affect MC1R?

A

alpha melanocyte stimulating hormone activates MC1R and stimulates a melanogenic cascade and eumelanin production

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12
Q

How does Agouti Signalling protein affect MC1R?

A

Antagonist - reverse the effects and elicits pheomelanin production

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13
Q

How does UV affect melanocytes?

A

Exposure leads to increase in MITF. expression and downstream melanogenic proteins. UV exposure also increases PAR2 in keratinocytes to increase melanosome uptake and distribution in keratinocytes

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14
Q

What is the epidermis made up of?

A

Keratinocytes

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15
Q

Where does division in the epidermis take place?

A

Basal layer

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16
Q

What are the layers of the epidermis?

A

Basal layer
Stratum spinosum
Stratum granulosum
Stratum corneum

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17
Q

What layer of epidermic may not always be present?

A

Stratum lucidum - present in between granular and corneum

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18
Q

What is different about the startup corneum and other epidermal layers?

A

No nuclei or organelles

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19
Q

How long does the process of cells progressing from basal layer to corner layer take?

A

30 days - alters with skin disorders

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20
Q

What does the keratinocyte cytoskeleton compose of?

A

Actin with microfilaments
Tubulin with microtubules
Intermediate keratin filaments

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21
Q

What is the role of keratins?

A 
Structure
Cell signalling 
Stress response
Apoptosis 
Wound healing
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22
Q

What intercellular junctions are found between keratinocytes?

A

Tight junction
Adherens
Gap junction
Desmosomes

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23
Q

What is the role of desmosomes?

A

Anchor keratin and bridge adjacent keratinocytes. Have a role in allowing the cell to withstand trauma

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24
Q

What is the role of gap junctions?

A

Intercellular channels
Connect adjacent keratinocyte cytoplasms
Essential for cell synchronisation, differentiation, growth and metabolic coordination

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25
Q

What is the role of adherens?

A

Transmembrane

Engage with actin skeleton

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26
Q

What is the role of tight junctions?

A

Barrier integrity

Cell polarity

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27
Q

What other cells do we find in the epidermis?

A

Melanocytes
Langerhans cells
Merkel cells
Mast cells

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28
Q

What are melanocytes?

A

Dendritic cells that distribute melanin in melanosomes to keratinocytes

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29
Q

What are langerhans cells?

A

Dendritic, antigen presenting cells

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30
Q

What are Merkel cells?

A

Mechanosensory receptors

31
Q

What are mast cells?

A

Immune response

32
Q

What is the basement membrane?

A

Dermal-epidermal junction

33
Q

What is the basement membrane made up of?

A

Proteins and glycoproteins (collagen IV and VII), laminins and integrins

34
Q

What is the role of the basement membrane?

A

Cell adhesion

Cell migration

35
Q

What is the role of the dermis?

A

Supporting (ECM) that provides resilience

36
Q

What are the main 2 layers of the dermis?

A

Papillary

Reticular

37
Q

Describe the papillary dermis

A

Superficial
Loose connective tissue
Vascular

38
Q

Describe the reticular dermis

A

Deep
Dense connective tissue
Forms the bulk of the dermis

39
Q

What is the dermis made up of?

A

Proteins
Glycoproteins
Ground substance

40
Q

What proteins make up the dermis?

A

Collagen (I and III) -80%

Elastic fibres elastin and fibrillin - 3%

41
Q

What glycoproteins make up the dermis?

A

Fibronectin
Fibulin
Integrins

42
Q

What is the role of glycoproteins in the dermis?

A

Facilitate cell adhesion and motility

43
Q

What ground substances are found in the dermis?

A

Glycosaminoglycan

Proteoglycan

44
Q

Where are ground substances found in the dermis?

A

Found between dermal collagen and elastic tissue

45
Q

What is the primary cell of the dermis?

A

Fibroblasts

46
Q

What other cells are found in the dermis?

A

Histiocytes, mast cells, neutrophils, lymphocytes, dermal dendritic cells.

47
Q

What types of blood supply do we have to the skin?

A

We have deep and superficial blood supply to make up 3 different vascular plexuses

48
Q

Where is the vascular plexus/blood supply found?

A

Subcutaneous plexus is found in the hypodermis
Reticular plexus is found in the reticular dermis
Superficial plexus found in papillary dermis
Does not cross into the dermis.

49
Q

What innervation do we have in the skin?

A

Sensory and autonomic

50
Q

What type of autonomic innervation do we have in the skin?

A

Cholinergic: eccrine seat glands
Adrenergic: eccrine and apocrine

51
Q

What areas do we find the most highly innervated at the skin?

A

Extremities, face and genitalia

52
Q

What types of afferent nerves do we have?

A

Corpuscles and free nerve endings

53
Q

What are corpuscular afferent nerves?

A

Encapsulated receptors restricted to dermis

54
Q

What are free afferent nerves?

A

Non encapsulated crossing into epidermis

55
Q

Describe meissner’s corpuscle

A

Encapsulated unmyelinated mechanoreceptor found in the papillary dermis. It’s responsible for sensing light touch (+ slow vibration) and is found in most thick hairless skin e.g. the finger tips.

56
Q

Describe Ruffini’s corpuscle

A 
Slow acting mechanoreceptor
Spindle shaped 
Deeper in dermis 
Found in finger nails 
Monitors skin stretching and slippage of objects
57
Q

Describe Pacinian (lamellar) corpuscle

A

Encapsulated mechanoreceptor
Rapid acting
Egg shaped
Senses deep pressure and vibration

58
Q

Describe Merkel Cells

A 
Non-encapsulated 
Oval shaped 
Mechanoreceptor
Found in epidermis 
Detects light or sustained touch and pressure
59
Q

Where do we find modified epidermal cells?

A

Stratum basal above the basement membrane. Most commonly found in the finger tips however also in the palms, soles, oral and genital mucosa.

60
Q

What does the skin microbiome consist of?

A

Viruses
Fungi
Bacteria
Composition varies with environment

61
Q

What are the main bacteria we find in the microbiome of skin?

A

Actinobacteria
Firmicutes
Bacteroidetes
Proteobacteria

62
Q

What is the role of the skin microbiome?

A

Immune modulation and epithelial health

Disease

63
Q

What are the 6 main functions of the skin?

A 
Immunological barrier 
Physical barrier
Thermoregulators 
Sensation
Metabolism 
Aethetic appearance
64
Q

How does the skin act as an immune barrier?

A

Langerhans cells act as sentinel cells and contribute to immune tolerance. However they extend their dendritic processes through intercellular junctions to monitor the external environment

65
Q

What happens when langerhans cells detect no threat?

A

They will promote expansion and activation of Treg cells.

66
Q

What happens when langerhans cells detect PAMPs?

A

This means they sense danger therefore rapidly activate the innate immune response and induce and adaptive immune response with specific T cells.

67
Q

What other cells are involved in immune defence of the skin?

A

Tissue resident T cells, macrophages, dendritic cells also carry out immune surveillance and provide rapid backup tif the epidermis is breached

68
Q

How does the skin act as a physical barrier?

A

Stratum corneum and cornfield cell envelope restrict water/protein loss

69
Q

How might we get visceral problems from extensive skin disease?

A

Loss of water and protein may be attributed to renal failure/ high output cardiac failure.

70
Q

What is the role of sub-cutaneous fat in the skin and its physical barrier?

A

Cushion trauma.

71
Q

Explain thermoregulation in the skin

A

Vasodilation/constriction of deep or superficial plexuses to regulate heat loss
Eccrine sweat glands also provide a cooling effect
Role in fluid balance

72
Q

Explain metabolic functions of the skin?

A

Vitamin D synthesis

Subcutaneous fat acts as a calorie reserve and releases leptin to act on the hypothalamus and stimulate satiety.

73
Q

What is the role of basal keratinocytes with melanin in the physical barrier of the skin?

A

Protect against UV induced damage.

BRS (16 decks)

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