Structure and Function of Skin - Schwarzenberger Flashcards Preview

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Flashcards in Structure and Function of Skin - Schwarzenberger Deck (79):
1

List 6 important functions of skin

- barrier function

- immune recognition and surveillance

- damage repair

- thermoregulation

- protection from UV radiation

- communication

2

List common functions of skin as a barrier

Regulates water loss

Protect against mechanical, chemical and microbial insults from outside world

3

Skin deals with innate or adapative immunologic processes? 

Both

Fun fact: skin has more lymphocytes than inside the body

4

Autoimmune bullous diseases are blistering skin diseases mediated by autoantibodies towards what? 

skin adhesion molecules (desmosomes, hemidesmosomes)

5

Characteristic features of autoimmune bulous diseases?

erosions or blisters in skin, often in mucosa

6

Autoantibodies to hemidesmosomes. Name this skin condition?

Bullous pemphigoid

7

Autoantibodies to desmosomes. Name this condition?

Pemphigus vulgaris

8

Bullous pemphigoid vs Pemphigus vulgaris. Which is which?

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Top = Pemphigus vulgaris

Bottom - Bullous pemphigoid

9

Immunofluorescence. Which is which

Bullous pemphigoid vs pemphigus 

Q image thumb

Top - Bullous Pempighoid

Bottom - Pemphigus Vulgaris

10

Impaired wound healing can lead to ?

chronic skin ulcers, risk of infection

11

Patients can also develop skin lesions bc they become ____ to injury? List 2 examples

insensitive

Neuropathic ulcers, trigeminal trophic syndrome

12

Melanin is found where in skin (epidermis/dermis). Purpose of it?

Found in epidermis, protect against UV radiation

13

Loss of photoprotection increases what 2 OBVIOUS risks?

risk of burning (duh), and skin cancer (duh)

14

Condition where person has abnormal pigment at birth?

Albinism

15

Condition where you lose your pigment as you get older?

Vitiligo

16

Acute effects of UV radiation on skin?

Inflammation (sunburn)

Immunosuppression

Tanning

Epidermal hyperplasia

Vitamin D photosynthesis

DNA damage (apoptosis, cell cycle arrest to repair)

 

17

What are the 2 chronic effects of UVR on skin?

Photoaging

Photocarcinogenesis (basal cell and squamous cell carcinomas, melanomas)

18

Term for histologic change that occurs due to chronic UV radiation

Solar elastosis (right picture)

Normal skin (left picture)

 

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19

Incidence of melanoma in US?

 

1 in 50

20

Melanoma more commonly associated with chronic low exposure or acute intense exposure?

Acute intense exposure

21

Disease of skin that deals with inability to repair DNA?

Xeroderma pigmentosum, DNA excision abnormal

22

What condition does he have?

Mutation in what gene? Consequence of this?

Clinical manifestations?

Q image thumb

Hypohidrotic ectodermal dysplasia

Mutation in EDAR (Ectodyplasin A receptor) gene. Protein is critical for proper interaction between developing ectoderm and mesorderm.

Results in abnormal hair follicles, sweat glands, and teeth. Unable to regulate temperature, overheat easily

23

3 layers of skin?

Epidermis, dermis, subcutis

24

Cells of epidermis? Which makes up the majority

Keratinocytes (90% of cells), melanocytes, langerhans cells, merkel cells

25

What cells of epidermis are important when they become malignant?

Merkel cells

26

if you cut your skin, and bleed, what layer of the skin have you at least affected?

Dermis, epidermis has no blood vessels

27

Dermis or epidermis?

Primarily barrier function, protection, wound healing?

Epidermis

28

Epidermis sheds itself every ___ days?

28+

14 days to reach stratum corneum

14 days to desquamate

29

4 Layers of Epidermis?

Stratum corneum, granulosum, spinosum, basale

A image thumb
30

Function of hemidesmosome?

Connect epidermis to dermis

Epidermis (pink in picture), dermis (blue)

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31

Function of desmosomes?

Keratinocyte to keratinocyte adhesion

32

What epidermal layer is the source of stem cells?

Stratum basale

33

Division of cells starts in what epidermal layer?

Stratum basale

34

Basal cells (of basal layer) adhere to basement membrane via what?

hemidesmosomes

35

Cells stop dividing and start terminal differentiation in what epidermal layer? 

Stratum spinosum

36

Lipids begin to develop in what epidermal layer?

Stratum spinosum

37

Why is the stratum spinosum "spiny"

Due to visible desmosomes with which one KC adheres to another

38

Profilaggrin synthesis occurs in what epidermal cell layer? 

 

Stratum granulosum

Profilaggrin makes up part of the intracellular keratohyaline granules that are produced in this layer

 

39

What layer of the epidermis plays a key role in maintaining a water barrier? How?

Stratum granulosum

- Lipids in lamellar granules secreted into intercellular space to form water barrier to keep water in skin

40

 Nuclei and organelle should degenerate by the time they reach what layer?

Stratum corneum

41

Profilaggrin is processed into ____ in the stratum ____? Purpose of this?

filaggrin, stratum corneum

- helps keep water in cells

42

Stratum corneum creates a protective layer via a combination of what 2 components?

Keratin + filaggrin = macrofibrils (creates protective layer)

43

Keratin combines to form _____?

Intermediate filaments

44

Pairs of keratin differ based on what?

location in the body.

Dif keratin pairs in palms/soles vs elsewhere

45

What amino acid is found in keratin (esp hair and nails)?

Cysteine (which contains sulfur. why your hair smells like shit when it gets burned)

46

Based on location within body, what layer of the epidermis has different characteristics? 

Stratum corneum varies based on different areas within body, such as trunk/back (thinner) vs palms/soles (thicker)

47

What layer of the epidermis is compared to a brick and mortar wall? What do #s 1 and 2 represent?

Q image thumb

Stratum corneum

1 (bricks) = flattened keratinocytes filled with keratin and filaggrin

2 (mortar) = lipid mixture surrounding keratinocytes, providing water barrier

48

Name for "pigment producting dendritic cells?"

What pigment is produced?

Melanocytes

- produce melanin (a radiation absorbing pigment)

49

Melanocytes are derived from what embryonic cell lineage?

Neural crest cells, migrat during embryonic development

50

Where are melanocytes located in the epidermis? What is their ratio to keratinocytes?

"live" along basal cell

1:10 ratio between melanocytes:keratinocytes

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51

In addition to producing melanin, what else do melanocytes do with melanin?

transfers melanin to surrounding keratinocytes

52

What is classified as the primary defense against UV radiation?

Melanocytes 

53

 What is this a picture of? 

Q image thumb

Melanocyte

Notice the dendritic like appendages within this diagram, same as picture 

A image thumb
54

 Besides melanocytes, name another dendritic cell of the epidermis? Where is its location in the epidermis?

Langerhans cells, found in mid epidermis

55

  Main purpose of Langerhans cells?

Recognize, take up, and present abnormal antigens in skin to lymphocytes in regional lymph nodes

- this abnormal antigen can be a cancerous cell, virally infected cell, chemical allergen (like a fragrance), etc

56

Name this cell: 

Epidermal cell associated with light touch sensation

Merkel cell

57

Merkel cells can develop into what pathologically?

malignant tumors

58

Name 2 cells found in dermis

Fibroblasts, mast cells

59

Besides fibroblasts/mast cells, what other components are found in dermis?

blood vessels and lymphatics, nerves, sweat and oil glands, hair follicles

60

3 functions of dermis?

Structural support

vascular support

innervation (epidermis has NO innervation or vasculature)

61

What is considered the primary cell in the dermis? What origin do these cells come from?

Fibroblast, mesenchymal origin

62

Main purpose of fibroblasts?

- Synthesis and degradation of CT proteins, including collagen, elastin, glycosaminoglycans, and other glycoproteins

- Injury to skin triggers fibroblast mitosis

- Responsible for wound healing and scar formation

63

What cells in the dermis are rich in histamine and heparin granules? 

Mast cells

- release their granules when triggered by injury or when they bind IgE antibodies during allergic reactions

- histamine and other mediators important in allergic reactions and wound healing

64

Hair follicles stop in dermis or continue into subcutis?

Extend through dermis into subcutis

65

Each hair follicle is associated with what gland?

sebaceous (oil) gland

66

What are the 4 components of a pilosebaceous unit?

- Hair follicle

- sebaceous (oil) gland

- apocrine sweat gland (in axilla and anogenital skin)

- arrector pili muscle

67

"True" sweat glands? Location in body?

Eccrine sweat glands, all over body (as opposed to apocrine found only in axilla/anogenital skin)

68

Are eccrine sweat glands associated with a hair follice?

 

No 

69

Apocrine vs eccrine sweat glands?

- function to regulate temperature by evaporative cooling of sweat?

Eccrine sweat glands

70

Fat layer found in what layer of skin?

Function of this layer?

Subcutis

insulation, source of energy, protection from injury

71

Cells/components of subcutis?

fat, blood vessels, fibrous septae

72

Other than structure, why are fibrous septae important?

B/c the cause cellulite (Fibrous septae pull down in between fat lobules)

OMG I HAVE CELLULITE

73

Apoptosis is (high or low) in epidermis?

Apoptosis normally low in epidermis, but can increase in some situations

74

If you get sunburn, what cells in what layer become damaged? Relate this to apoptosis

Sun-damaged cells = damaged keratinocytes in epidermis

Apoptosis will increase (normal response to sun damaged cells)

75

What happens if apoptosis of sun-damaged cells (keratinocytes) doesnt occur?

Can progress to skin cancer

76

What disorder is shown in picture? 

Associated with genetic defects in what protein?

Q image thumb

Atopic dermatitis, defects in filaggrin

77

What disease is shown here? What mutation is occuring?

Q image thumb

Epidermolysis Bullosa Simplex

genetic mutations in Keratin 5/14

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78

Definition of nevus (mole)?

Benign collection of melanocytes

79

Melanoma definition?

growth of malignant (cancerous) melanocytes