DD 03-03-14 08-09am Clinical Dermatology-Terminology and Functions - Dunnick Flashcards Preview

Unit 3 D&D > DD 03-03-14 08-09am Clinical Dermatology-Terminology and Functions - Dunnick > Flashcards

Flashcards in DD 03-03-14 08-09am Clinical Dermatology-Terminology and Functions - Dunnick Deck (93):
1

Skin - key factos

Skin is the largest organ
– Weight 4 kg
– Covers 2 square meters of surface area
Skin diseases are common!
– 8.5% diagnoses in Family Practice Clinics
– 30% Pediatric Conditions
Significant economic burden in treating skin disease & skin disease causing loss of days worked.

2

Function of the skin

1. Decoration/Beauty
2. Barrier-- Physical, LIght, Immunologic
3. Vitamin D synthesis
4. Water Homeostasis
5. Thermoregulation
6. Insulation/Calorie Reservoir
7. Touch/Sensation

3

Structure/Cells Involved in Skin's Function as a Physical Barrier

Epidermis, Keratinocytes

4

Structure/Cells Involved in Skin's Function as a Light Barrier

Epidermis: Melanocyte

5

Structure/Cells Involved in Skin's Function as a Immunologic Barrier

Epidermis: Langerhans cells

6

Structure/Cells Involved in Skin's Function in Vitamin D synthesis

Epidermis: Keratinocytes

7

Structure/Cells Involved in Skin's Function in Water homeostasis

Epidermis: Keratinocytes
Adnexa: Eccrine glands

8

Structure/Cells Involved in Skin's Function in Grasp

Adnexa: Nails

9

Structure/Cells Involved in Skin's Function in Lubrication of the Skin

Adnexa: Sebaceous glands

10

Structure/Cells Involved in Skin's Function in Phermones/ Body Odor

Adnexa: Apocrine glands

11

Structure/Cells Involved in Skin's Function in Thermoregulation

Adnexa: Eccrine glands
Dermis: Blood vessels

12

Structure/Cells Involved in Skin's Function in Strength & Elasticity

Dermis: Fibroblast (Produces collagen and elastin)

13

Structure/Cells Involved in Skin's Function in Sensation

Dermis: Nerves

14

Structure/Cells Involved in Skin's Function in Insulation

Subcutaneous Fat

15

Structure/Cells Involved in Skin's Function as a Calorie Reserve

Subcutaneous Fat

16

Fitzpatrick Skin Type I

Hair - Red/Blond
Eyes - Blue/Green
Skin - White
Freckles - +++
Sunburn - Always
Tan - 0

17

Fitzpatrick Skin Type II

Hair - Blond/Brown
Eyes - Light to Medium
Skin - Fair
Freckles - ++
Sunburn - Easily
Tan - Minimally

18

Fitzpatrick Skin Type III

Hair - Brown
Eyes - Medium to Dark
Skin - Light Brown
Freckles - +
Sunburn - Initially
Tan - Gradually

19

Fitzpatrick Skin Type IV

Hair - Medium to Dark
Eyes - Dark
Skin - Moderate Brown
Freckles - 0
Sunburn - Minimally
Tan - Tans Well

20

Fitzpatrick Skin Type V

Hair - Dark
Eyes - Dark
Skin - Dark Brown
Freckles - 0
Sunburn - Rarely
Tan - Dark Tan

21

Fitzpatrick Skin Type VI

Hair - Dark
Eyes - Dark
Skin - Black
Freckles - 0
Sunburn - Never
Tan - Always Tan

22

Components of the skin

Epidermis
Dermis
Adnexal structures
Subcutaneous Fat

23

Epidermis

a stratified squamous epithelial layer

24

Dermis

An underlying CT layer, which includes:
- papillary layer (loose CT) immediately under epidermis
- deeper reticular layer (dense CT)

25

Adnexal structures

- Apocrine glands
- Eccrine glands
- Hair
- Nails
- Sebaceous glands

26

Subcutaneous Fat

Composed of adipocytes

27

Regional variation of skin

Thick skin is hairless & found on the palms / soles

28

Vitamin D Synthesis

1. 7-dehydrocholesterol converted to cholecalciferol (Vitamin D3) in skin by UVB
2. Cholicalciferol (Vitamin D3) & Ergocalciferol (Vitamin D2) can both be ingested & absorbed through intestines.
3. Vit D2 & D3 then converted to calcidiol (25-hydroxy Vitamin D) by liver.
4. 1,25-dihydroxy-Vitamin D (calcitriol) is active form & is synthesized by kidneys.

29

Cells of the Epidermis

Keratinocytes
Melanocytes
Langerhans cells

30

Keratinocytes

- Form barrier layer
- Synthesize keratin (major intracellular fibrous protein of skin)
- Involved in defined cycle of proliferation, differentiation, & apoptosis

31

Melanocytes - defition / source / location

- Pigment producing cells arising from neural crest
- Located primarily in basal layer of epidermis, in hair follicles
- Reside in basal layer of epidermis in 1:10 ratio (melanocyte:keratinocyte)

32

Melanocytes - action

- Synthesize melanin (tyrosin-derived pigment)
- Melanin is packaged in granules (melanosomes)
- These granules are transferred from melanocytes to keratinocytes via dendritic processes
- Ea/ melanocyte supplies melanin to ~30 nearby keratinocytes
- Melanin in basal keratinocytes protects DNA from UV damage

33

Langerhans cells

= Dendritic cells in epidermis derived from bone marrow stem cell
- Found in small numbers in all epidermal layers
- Participate in cell-mediated immune reactions by processing & presenting antigens (circulate back and forth between skin & lymph nodes)

34

Skin color variation

NOT due to the number of melanocytes in the skin
DUE TO:
- The type of melanin produced:
- The distribution melanosomes

35

Types of melanin produce

Eumelanin: black to brown pigment
Pheomelanin: yellow to red-brown pigment

36

Distribution of melanosomes in skin

Light Skin:
- melanosomes distributed in clusters above nucleus
Dark Skin:
- melanosomes distributed individually throughout cytoplasm

37

Life cycle of Keratinocytes

- Epidermis is continually renewed by mitosis of keratinocytes in the basal layer & by shedding of dead keratinocytes from the surface
- Process typically takes 28 days
- The layered nature of the epidermis (5 layers) is an expression of this developmental sequence

38

Layers of the Epidermis

1. Stratum basalis (germinativum) = Basal cell Layer
2. Stratum spinosum
3. Stratum granulosum
4. Stratum lucidum
5. Stratum corneum

39

Stratum basalis (germinativum) = Basal cell Layer

- deepest layer of epidermis
- Consists of a single layer of columnar or cuboidal cells (keratinocytes)
- Basal keratinocytes are the stem cells of the epidermis (source of new keratinocytes & thus a site of intense proliferation)

40

Cell attachments in Basal Cell Layer of Epidermis

Hemidesmosomes:
- attach basal cells are firmly to basal lamina of dermal epidermal junction

Desmosomes:
- attach keratinocytes to each other

Tonofilaments:
- protein structures (keratin filaments) that insert into dense plaques of desmosomes on cytoplasmic side of plasma membrane

41

Stratum spinosum ;ayer of Epidermis

- Has a “prickly” or spiny appearance due to desmosome attachments between cells
- Intercellular adhesion depends upon tonofilament-desmosome interaction in the distribution of stress
- Synthesis of involucrin & membrane coating granules begins in this layer

42

Stratum granulosum layer of Epidermis

- Cells of this layer contain different types of granules
- Keratohyalin granules contain Profilaggrin (filaggrin precursor).
--> Filaggrin cross-links keratin tonofilaments & is important in barrier function of skin
* Filaggrin is mutated in dry skin conditions including ichthyosis & atopic dermatitis

43

Stratum lucidum layer of Epidermis

- Under light microscope, a thin, light staining band seen only in thick skin
- Cells of this layer no longer have nuclei or organelles

44

Stratum corneum layer of Epidermis

- Outermost layers of epidermis
- Keratinocytes have lost their nuclei & organelles and entire cell is filled with keratin
- Desmosomes still connect tightly packed adjacent cells

45

Layers of the Dermis

Papillary Layer
Reticular Layer

46

Papillary Layer

- site of attachment to epidermis & necessary to its development / differentiation
- contains capillary network (blood supply for epidermis)
- pathway for defense cells
- contains Meissner's corpuscles which sense touch

47

Reticular Layer

- contains extensive collagen & elastic fibers that provide strength & flexibility
- houses (along w/hypodermis) epidermal derivatives such as glands & hairs, and plays major role in their development & functioning
- pathway for major blood vessels arranged specifically to facilitate thermoregulation
- site of nerve tracts & major sensory receptors
- Pacinian corpuscles sense vibration, pressure & touch

48

Encapsulated touch receptors

In dermis
Include:
- Meissner’s corpuscles
- Pacinian corpuscles

49

Meissner’s corpuscles

- detect delicate touch
- most commonly found in dermal papillae of thick skin
- consist of Schwann cells & sensory nerve terminals wrapped by fibroblasts & collagen

50

Pacinian corpuscles

= rapidly adapting receptors that detect changes in deep pressure (vibrations)
- found in dermis of both thin & thick skin
= large structures resembling an onion
- concentric layers are composed of flattened CT-like cells interspersed w/ intercellular fluid & collagen
- single sensory nerve fibers terminates w/in this structure

51

Adnexal Structures of the Skin

Apocrine sweat glands
Eccrine sweat glands
Hair
Nails
Sebaceous glands

52

Apocrine sweat glands

- Specialized sweat glands located in axillary, pubic & perianal regions
--> produce milky, viscid, carb-rich secretion that is initially odorless
--> subsequent bacterial action leads to a characteristic axillary body odor
- begin to function in puberty
- have ducts which empty into hair follicles just above sebaceous glands

53

Eccrine sweat glands

- Traditional sweat glands distributed over most of the body
* Not found in lips, under nails or on glans penis, glans clitoris, or labia minora

--> Watery, enzyme-rich secretion
- initially isotonic
- becomes hypotonic as Na+ reabsorbed by ducts

- Important for thermoregulation

54

Hair

- Develop in utero w/ downgrowth of epidermis forming a pilosebaceous unit
- Hair itself consists of central medulla of soft keratin + cortex & cuticle of hard keratin
- Hair growth is intermittent (growth period of 2-3 years followed by rest period of several months)
- Pigment comes from melanocytes at base of hair
- W/contraction of arrector pili muscle (smooth muscle), hairs stand on end (“goose bumps”)

55

Sebaceous glands

- Oil glands which secrete sebum (complex mixture of lipids)
- develop along w/ hair follicles & empty their secretion into upper 1/3 of hair follicles
- development accelerated at puberty

56

Types of Primary Skin Lesions

Macule < Patch
Papule < Nodule < Tumor
Plaque
Scale
Wheal
Vesicle < Bulla
Pustule
Atrophy < Erosion < Ulceration

57

Macule

- Circumscribed change in skin color that is flush w/ surrounding skin
- Lesion is <1.0 cm in diameter (smaller than patch)

Examples:
Solar lentigo
Traumatic purpura

58

Patch

- Circumscribed change in skin color that is flush w/ surrounding skin
- Lesion is ≥1.0 cm in diameter (bigger than macule)

Examples:
Café au lait spot
Vitiligo

59

Papule

= A solid or cystic elevation
- <1.0 cm in diameter (smaller than nodule & tumor)

Examples:
Acne
Eruptive xanthoma

60

Nodule

= A solid or cystic elevation
- >1.0 cm but <2.0 cm in diameter (larger than papule, smaller than tumor)
- Example: Dermato-fibroma

61

Tumor

- A solid or cystic elevation
- >2.0 cm in diameter (larger than papule/nodule)
- Example: Follicular cyst

62

Plaque

- An elevated lesion that is >1.0 cm in diameter
- Example: Psoriasis

63

Scale

= Desiccated, thin plates of cornified epidermal cells that form flakes on the skin surface
- Example: Ichthyosis

64

Wheal

= Circumscribed, flat-topped, firm elevation of skin with a well-demarcated and palpable margin
- Example: Urticaria

65

Vesicle

= Circumscribed, elevated lesion containing clear serous or hemorrhagic fluid
= <1 cm in diameter (smaller than bulla)

Examples:
- Contact dermatitis
- Herpes simplex

66

Bulla

= Circumscribed, elevated lesion containing clear serous or hemorrhagic fluid
= >2 cm in diameter (larger than vesicle)
- Example: Bullous pemphigoid

67

Pustule

= A vesicle containing purulent exudate
- Example: Folliculitis

68

Atrophy

= A depression from the surface of the skin with underlying loss of epidermal or dermal substance (less severe loss than erosions & ulcerations)
- Example: Lichen sclerosis et atrophicus

69

Erosion

= A depression from the surface of the skin with a loss of all or part of the epidermis (more severe loss than atrophy, less severe than ulcerations)
- Example: Burn

= Can be a secondary lesion
- Example: Ruptured bulla

70

Ulceration

- A depression from the surface of the skin with a loss of the entire epidermis and at least some of the dermis (more severe loss than atrophy & erosion)
- Example: Ecthyma

71

Secondary Lesions result from...

- external forces such as scratching, picking, infection or healing of primary lesions

72

Types of Secondary Lesions

Lichenification
Scar
Fissure
Crust

73

Lichenification

= Dry, leathery thickening of the skin with exaggerated skin markings
- EX: Chronic eczema

74

Scar

= An elevated or depressed area of fibrosis of the dermis or subcutaneous tissue resulting from an antecedent destructive process
- EX: Healing wound

75

Fissure

= A deep linear split in the skin extending through the epidermis
- EX: Traumatized eczema

76

Crust

= Dried exudates of serum, blood, sebum, or purulent material on the surface of the skin
- EX: Acute and/or secondarily infected eczema

77

Disease caused by Skin chronically exposed to sunlight (face, neck, hands, arms)

Actinic keratosis
Basal cell carcinoma
Squamous cell carcinoma

78

Skin disease in central chest, shoulders, & earlobes

Keloids

79

Skin disease in extensor arms and legs, intragluteal cleft, umbilicus

Psoriasis

80

Skin disease in antecubital fossa, popliteal fossa

Atopic dermatitis

81

Skin disease in anterior surface of lower legs

Palpable purpura
Pretibial myxedema
Necrobiosis lipoidica diabeticorum
Erythema nodosum

82

Skin disease in axilla & inguinal areas

Hidradenitis suppurativa

83

Skin disease in posterior neck & back

Folliculitis

84

Skin disease in web spaces of toes & sides of feet

Tinea pedis

85

Skin disease in web spaces of fingers & wrists

Scabies

86

Skin disease in palms & soles

Secondary syphilis
Erythema multiforme

87

Skin disease with Clustered arrangement

Herpes simplex

88

Skin disease with Grouped arrangement

Lichen planus
Granuloma annulare

89

Skin disease with Linear arrangement

Allergic contact dermatitis

90

Skin disease with Zosteriform arrangement

Herpes zoster

91

Skin disease with Annular arrangement w/out scale

Urticaria
Hansen disease (leprosy)

92

Skin diseases with Annular arrangement with scale

Dermatophytosis
Pityriasis rosea

93

Skin diseases with Coalescing arrangment

Psoriasis
Drug hypersensitivity eruption
Viral exanthema
Urticaria