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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
Q

What signaling is needed for hair development

A

Hedgehog signaling by the signaling transducer known as smoothened appears critical for hair development

26
Q

What are the secretory cell of the eccrine sweat unit

A
  1. Glycogen rich, large pale cells that initiate the formation of sweat
  2. Darker staining, smaller cells
27
Q

Where are eccrine sweat units found

A

Virtually all skin sites

28
Q

What is the acrosyringium

A

The intraepidermal spiral duct, which opens directly to the skin surface

29
Q

What is the function of the eccrine gland

A

serve a thermo-regulatory function

- Most abundant on palms, soles, forehead and axillae

30
Q

What mediates sweat production from the eccrine sweat unit

A

cholinergic innervation

31
Q

What is the apocrine unit

A

Coiled secretory gland that is located at the junction of the dermis and subcutaneous fat

32
Q

What is secreted by the apocrine unit

A

Protein, carbohydrates, ammonia, lipid and iron

33
Q

What causes the odiferous secreted product by the apocrine unit

A

Apocrine sweat is odorless until it reaches the skin surface, where it is altered by bacteria

34
Q

Where are apocrine sweat units found

A 
axillae
areolae
anogenital area
external auditory canal
eye lids
35
Q

When do apocrine sweat units begin to function

A

puberty

36
Q

Embryologically, where are hair follicles derived

A

During embryogenesis, mesenchymal cell in the fetal dermis collect immediately below the basal layer of the epidermis

37
Q

Discuss the development of the hair follicle

A

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
Q

What is the portion of the follicle between the sebaceous duct and the insertion of the arrestor pili muscle

A

the isthmus

39
Q

What is anagen

A

The growth phase, lasts about 3-5 years

40
Q

What is the predominant phase of hair growth

A

Anagen; 85-90% of scalp hairs

41
Q

What is the rate of growth of scalp hairs in anagen phase

A

0.37mm/day

42
Q

What is catagen

A

involution of hair growth, lasts about 2 weeks

43
Q

What is telogen

A

the resting phase of hair growth, lasts about 3-5 months

44
Q

How does the hair growth cycle

A

Hair growth is cyclical, however, each follicle functions as individual unit

45
Q

What is the result of synchronous termination of anagen or telogen

A

Telogen effluvium
- most commonly the result of early release from anagen, such as that induced by a febrile illness, surgery or weight loss

46
Q

How does pregnancy effect hair growth

A

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
Q

Discuss the shape of hairs of white people

A

The scalp hairs are round

Pubic hair, beard hair and eyelashes are oval

48
Q

What is the shape of scalp hair of black people

A

oval

49
Q

What shape is uncombable hair

A

triangle

50
Q

Where are sebaceous glands found

A

The greatest abundance are found on the face and scalp, though they are distributed to all skin sites except palms and soles

51
Q

What are secreted from sebaceous glands

A

wax esters and squalene are unique secretory products

52
Q

What is the rate of growth for finger nails

A

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
Q

What causes brittle nails

A

Demonstrate widening of the intracellular space between nail keratinocytes on electron microscopy

54
Q

Embryologically, where is the dermis derived

A

mesodermal, except for nerves, which like melanocytes are derived from neural crest

55
Q

What is the major component of the dermis

A

Type I collagen

56
Q

Where is type VII collagen produced

A

Keratinocytes

57
Q

What is the meisner corpuscle

A

mediates touch and pressure and found in the dermal papillae, particularly on the digits, palms and soles

58
Q

What is the water pacini corpuscles

A

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
Q

How is histamine evoked itch transmitted to the CNS

A

slow conducting unmyelinated C-polynodal neurons

Andrews Diseases Of Skin (5 decks)

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