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Derm Mine > Histology > Flashcards

Histology Flashcards

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Dermatology Board Prep flashcards
1
Q

How many skin diseases are known?

A

> 2000

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2
Q

What proportion of GP consultations have to do with skin complaints?

A

~ 20%

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3
Q

What does skin comprise

A

Epidermis
Dermo-epidermal junction
Dermis
Sub-cutis (mostly fat)

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4
Q

Where does the epidermis arise?

A

Ectoderm forms a single-layered periderm
Number of layers increase
Periderm cells cast off

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5
Q

Where does the dermis come from?

A

Formed from mesoderm below ectoderm

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6
Q

Where do melanocytes come from?

A

Neural crest

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7
Q

Name the layers of skin present at 4 weeks of foetal development.

A

Periderm
Basal layer
Dermis

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8
Q

Name the layers of skin present at 16 weeks of foetal development.

A 
Keratin layer
Granular layer
Prickle cell layer
Basal layer (with melanocytes)
Dermis
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9
Q

What is the growth pattern of skin?

A

Along Blaschko’s lines. Does not follow vessels, lymphatics or nerves

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10
Q

Name 4 skin appendages

A

Nails
Hair
Glands e.g. sebaceous
Mucosae e.g. buccal

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11
Q

Describe the epidermis/

A

4 defined layers +
Melanocytes
Langerhans cells
Merkel cells

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12
Q

Control of epidermal turnover is mediated by:

A

Growth factors
Cell death
Hormones

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13
Q

Name 2 conditions wherein there is loss of control of epidermal turnover

A

Skin cancer

Psoriasis

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14
Q

How long does it take the average keratinocyte to migrate from the basement membrane to shedding

A

28 days

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15
Q

Describe the basal layer (4 features)

A

One cell thick
Small cuboidal cells
Lots of INTERMEDIATE keratin filaments
High metabolically active

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16
Q

Describe the prickle cell layer (3 features)

A

Larger polyhedral cells
Lots of desmosomes
Intermediate filaments connect to desmosomes

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17
Q

Describe the granular layer (6 features)

A 
2-3 layers of flatter cells
Large keratinohyallin granules with filaggrin and involucrin proteins
Odland bodies present
High lipid content
Origin of cornified envelope
Cell nuclei lost
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18
Q

Describe the keratin layer (3 features)

A

Made of corneocytes; is the insoluble cornified envelope
Tight waterproof barrier
Lamellar granules release lipid

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19
Q

Describe melanocytes

A

Migrant cells from the neural crest to basal layer
During first 3 months of foetal development
Produce melanin
Form protective cap over nucleus

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20
Q

Describe melanosomes

A

Organelles of melanocytes
Convert tyrosine to melanin pigment
Transferred between adjacent keratinocytes via dendrites

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21
Q

What colour pigment does Eumelanin yield?

A

Brown or black

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22
Q

What colour pigment does Phaeomelanin yield?

A

Red, yellow

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23
Q

Define vitiligo

A

Autoimmune disease with loss of melanocytes

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24
Q

Define albinism

A

Genetic partial loss of pigment production in the skin

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25
Q

Describe Nelson’s Syndrome

A

Disorder wherein melanin stimulating hormone is produced in excess by the pituitary
May indicate pituitary malignancy

26
Q

Describe 4 features of Langerhans cells

A

Have a mesenchymal origin (bone marrow)
Found in the prickle cell level, dermis and lymph nodes
Involved in skin immune system
Characteristically contain Birbeck granules (tennis rackets)

27
Q

Describe Merkel cells (2 features)

A

Found in the basal layer

Myelinated mechanoreceptors

28
Q

Describe pilosebaceous units

A

Specialised keratins + adjacent sebaceous glands
Comprises an epidermal component + dermal papilla
Hair pigment comes from melanocytes above dermal papilla

29
Q

Name the phases of hair growth

A 
Anagen = growing			Catagen = involuting
Telogen = resting
30
Q

What phase of hair growth is the papilla still attached to the hair?

A

Anagen

31
Q

Decribe alopecia areata

A

Autoimmune hair loss

32
Q

Describe nails

A

Specialised keratins

Those on fingers grow faster than on toes

33
Q

What are the 3 parts of the nail plate?

same as matrix subdivisions

A

Dorsal (outermost)
Intermediate
Ventral (closest to nailbed)

34
Q

What is the dermo-epidermal junction?

A
  • interface between epidermis and dermis

- role in support, growth, adhesion, barrier and filter between epithelium and mesenchymal cells

35
Q

What are the parts of the DEJ?

A 
Lamina lucida (top part)
Lamina densa (bottom)
36
Q

Name an inherited disease of the DEJ

A

Epidermolysis bullosa

- simplex or dystrophic

37
Q

Name acquired diseases of the DEJ

A

Pemphigus
Pemphigoid
Dermatitis herpetiformis

38
Q

Describe Epidermolysis Bullosa simplex

A

Baby has fragile skin

Even holding them causes skin to tear

39
Q

Describe Epidermolysis Bullosa dystrophica

A

Skin over-heals

Toes and fingers may end up sticking together

40
Q

Name the components of the dermis

A 
Collagen (Type I and III)
Elastin
Ground substance
Blood vessels, lymphatics, nerves
Fibroblasts, macrophages, mast cells, langerhans cells
41
Q

What do fibroblasts in the dermis produce?

A

Collagen

Elastic fibres

42
Q

Describe the blood supply through the skin

A

Arteriole –> precapillary sphincters –> arterial capillaries –> venous capillaries –> post-capillary venules –> collecting venules

43
Q

What is a haemangioma?

A

Overgrowth of local blood vessels

May lead to port wine stains

44
Q

Lymphatic dysfunction may lead to:

A

Lymphoedema

- leads to cellulitis, vasculitis and other infections

45
Q

Name the nerves in the skin

A 
Somatic: Free nerve endings
Pascinian corpuscles
Meissners corpuscles
Autonomic: to blood vessels and glands
Control sweating
46
Q

What is neurofibromatosis?

A

Benign skin tumours

Cutaneous nerves are abnormally thickened

47
Q

Name the 3 types of skin glands

A

Sebaceous
Apocrine
Eccrine

48
Q

Describe sebaceous glands

A

Wide distribution but especially on face and chest
Hormone-sensitive (androgens)
Produces sebum
Open into hair follicles

49
Q

Describe acne

A

Increased sebum production
Blocked ducts
Increased bacterial activity

50
Q

Describe apocrine sweat glands

A

Part of pilosebaceous unit
Found in axillae and perineum
Androgen dependent
Scent

51
Q

Describe eccrine sweat glands

A

Opens directly onto skin surface
Widespread, esp palms, soles, axillae
Sympathetic cholinergic nerve supply
Cool the body by evaporation

52
Q

Name 6 functions of the skin

A 
Barrier function 
Metabolism & detoxification
Thermoregulation
Immune defence
Communication
Sensory functions
53
Q

How does skin act as a barrier?

A

Physically: mechanical trauma, UVR
Chemical: allergens, toxins
Pathogens: bacteria, viruses, fungi

54
Q

Describe the skin’s metabolic activity

A

Vitamin D metabolism

Thyroid hormone metabolism

55
Q

What are the steps of vitamin D metabolism?

A

Presence of 290-320nm UV light
Leads to formation of D3
Stored in the liver

56
Q

How is thyroid hormon formed?

A

Conversion of T4 to T3
80% of this happens in skin
20% in thyroid gland

57
Q

How does skin affect social interactions and communication?

A

Visual
Odour
Socio-sexual

58
Q

What is the papillary dermis?

A

Layer nearest to the epidermis

Thin

59
Q

What is the reticular dermis?

A

Thicker
Type I collagen
Contains appendage structures

60
Q

What does the epidermal basement membrane comprise?

A

Laminin

Collagen IV

Derm Mine (7 decks)

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