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Andrews Diseases Of Skin > Chapter 1: Skin - Basic Structure and Function > Flashcards

Chapter 1: Skin - Basic Structure and Function Flashcards

1
Q

What is periderm

A

The non keratinizing cuboidal cells that cover a fetus during the first weeks of life

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2
Q

Keratin of the epidermis is what embryologic derivative

A

Ectoderm origin

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3
Q

During development, when do the adnexal units, particular follicles and eccrine sweat glands originate

A

3rd month of life

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4
Q

What are the three basic cell types of the epidermis

A
  1. Keratinocytes
  2. Melanocytes
  3. Langerhans cells
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5
Q

What is the function of merkel cells

A

Act as slow adapting touch receptors

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6
Q

Where are merkel cells found

A

Basal layer of the palms and soles, oral and genital mucosa, nail bed and follicular infundibula

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7
Q

What are the zones of the epidermis (from deep to superficial)

A
  • Basal (stratum germinativum)
  • Prickle (Stratum spinosum)
  • Granular (stratum granulosum)
  • Stratum lucidum (Palms and soles only)
  • Horny Layer (stratum corneum)
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8
Q

What is the function of the lamellar granules

A

Appear in the interface between the granular and cornified cell layers which contribute to skin cohesion and impermeability

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9
Q

How do glycolipids such as ceramides effect the epidermis

A

contribute a water barrier function to skin and are commonly found in topical products meant to resort epidermal barriers

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10
Q

What can keratinocytes secrete

A

A wide array of cytokines and inflammatory mediators, including tumor necrosis factor (TNF-a)

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11
Q

What surface molecules do keratinocytes express

A

Intracellular adhesion molecule-1 (ICAM-1) and
major histocompatibility complex II (MHC II)

Keratinocytes actively respond to immune effector signals

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12
Q

Where are melanocytes derived from?

A

Neural crest cells

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13
Q

When can melanocytes be found during fetal development

A

8th week

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14
Q

What causes the racial differences in skin color

A

NOT by difference in the number of melanocytes.

It is the number, size and distribution of the melanosome (pigment granules) with in keratinocytes

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15
Q

What type of cells are melanocytes

A

Dendritic cells

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16
Q

What is the role of the melanocyte?

A

pigments within the melanocytes serve to protect themselves against photo damage such as UV-1 induced membrane damage

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17
Q

What is vitiligo

A

Affected skin becomes white because of destruction of melanocytes

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18
Q

What is albinism

A

The number of melanocytes are normal, but unable to synthesize fully pigmented melanosomes because of defects in the enzymatic formation of melanin

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19
Q

Where are langerhan cells typically found in the epidermis

A

scattered among keratinocytes of the stratum spinosum

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20
Q

Where are langerhan cells derived from

A

Monocyte-macrophage lineage and originate in the blood marrow

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21
Q

What forms the junction of the dermis and epidermis

A

basement membrane zone

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22
Q

What type of collagen is the major component of the basal lamina

A

Type IV collagen

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23
Q

What type of collagen is the major component of the anchoring fibrils

A

Type VII collagen

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24
Q

What makes up the skin adnexa

A

Eccrine and apocrine glands, ducts and pilosebaceous units

25
What signaling is needed for hair development
Hedgehog signaling by the signaling transducer known as smoothened appears critical for hair development
26
What are the secretory cell of the eccrine sweat unit
1. Glycogen rich, large pale cells that initiate the formation of sweat 2. Darker staining, smaller cells
27
Where are eccrine sweat units found
Virtually all skin sites
28
What is the acrosyringium
The intraepidermal spiral duct, which opens directly to the skin surface
29
What is the function of the eccrine gland
serve a thermo-regulatory function | - Most abundant on palms, soles, forehead and axillae
30
What mediates sweat production from the eccrine sweat unit
cholinergic innervation
31
What is the apocrine unit
Coiled secretory gland that is located at the junction of the dermis and subcutaneous fat
32
What is secreted by the apocrine unit
Protein, carbohydrates, ammonia, lipid and iron
33
What causes the odiferous secreted product by the apocrine unit
Apocrine sweat is odorless until it reaches the skin surface, where it is altered by bacteria
34
Where are apocrine sweat units found
``` axillae areolae anogenital area external auditory canal eye lids ```
35
When do apocrine sweat units begin to function
puberty
36
Embryologically, where are hair follicles derived
During embryogenesis, mesenchymal cell in the fetal dermis collect immediately below the basal layer of the epidermis
37
Discuss the development of the hair follicle
Along one side of the fetal follicle, two buds are formed: 1. Upper - develop into a sebaceous gland 2. Lower - becomes attachment for arrestor pili muscle Primary follicles are surrounded by two secondary follicles
38
What is the portion of the follicle between the sebaceous duct and the insertion of the arrestor pili muscle
the isthmus
39
What is anagen
The growth phase, lasts about 3-5 years
40
What is the predominant phase of hair growth
Anagen; 85-90% of scalp hairs
41
What is the rate of growth of scalp hairs in anagen phase
0.37mm/day
42
What is catagen
involution of hair growth, lasts about 2 weeks
43
What is telogen
the resting phase of hair growth, lasts about 3-5 months
44
How does the hair growth cycle
Hair growth is cyclical, however, each follicle functions as individual unit
45
What is the result of synchronous termination of anagen or telogen
Telogen effluvium - most commonly the result of early release from anagen, such as that induced by a febrile illness, surgery or weight loss
46
How does pregnancy effect hair growth
Pregnancy is typically accompanied by retention of an increased number of scalp hairs in the anogen phase, as well as the prolongation of telogen
47
Discuss the shape of hairs of white people
The scalp hairs are round | Pubic hair, beard hair and eyelashes are oval
48
What is the shape of scalp hair of black people
oval
49
What shape is uncombable hair
triangle
50
Where are sebaceous glands found
The greatest abundance are found on the face and scalp, though they are distributed to all skin sites except palms and soles
51
What are secreted from sebaceous glands
wax esters and squalene are unique secretory products
52
What is the rate of growth for finger nails
0.1 mm/day. Requires about 4-6 months to replace a complete nail plate (hand) and 12-18 months to replace the great to nail (foot).
53
What causes brittle nails
Demonstrate widening of the intracellular space between nail keratinocytes on electron microscopy
54
Embryologically, where is the dermis derived
mesodermal, except for nerves, which like melanocytes are derived from neural crest
55
What is the major component of the dermis
Type I collagen
56
Where is type VII collagen produced
Keratinocytes
57
What is the meisner corpuscle
mediates touch and pressure and found in the dermal papillae, particularly on the digits, palms and soles
58
What is the water pacini corpuscles
located in the deeper portions of the dermis, mediate touch and pressure, found in the deeper portions of the dermis of weight bearing surfaces and genitalia
59
How is histamine evoked itch transmitted to the CNS
slow conducting unmyelinated C-polynodal neurons

Andrews Diseases Of Skin (5 decks)

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