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Flashcards in Introduction to Skin Deck (63)
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1
Q

What are the three main layers of skin?

A

Epidermis, dermis and hypodermis (fat layer)

2
Q

What is keratin?

A

Keratin is an intermediate filament that is most abundant in the stratum corneum (top layer), hair and nails.

3
Q

Where is keratin most abundant in the skin?

A

Epidermis, stratum corneum (top layer), hair and nails too

4
Q

What are the two types of keratin?

A

Soft (alpha) and hard (beta) - determined by the secondary structure and suffice bridges

5
Q

What are the four main layers of the epidermis?

A

Stratum corneum, stratum granulosum, stratum spinosum and stratum basale

6
Q

Describe the stratum corneum layer of the epidermis

A

Protective layer of the skin with dead cells and intercellular lipids (ceramics) to maintain skin moisture

7
Q

Describe the stratum granulosum layer of the epidermis

A

This is 2-3 cells thick and has large granules of keratohyalin

8
Q

Describe the stratum spinosum layer of the epidermis

A

3-4 cells thick with many desmosomes to separate the keratinocytes which gives the layer a spiny appearance

9
Q

Describe the stratum basale layer of the epidermis

A

Proliferation of epithelial cells occurs here and cells are slightly denser

10
Q

Describe the composition of the basement membrane of the epidermis of the sin

A

ECM consists of laminin 332, collagen IV and collagen VII

11
Q

What is the role of the basement membrane in the epidermis?

A

To provide cell polarity, regulate basal function and to anchor the epidermis to the dermis

12
Q

What is the function of the hemidesmosomes in the basement membrane of the epidermis?

A

Bind the keratin cytoskeleton to the basement membrane

13
Q

What is the role of the dermis?

A

Provides strength and elasticity to the skin

14
Q

What is the most abundant cell in the dermis?

A

Fibroblasts

15
Q

What is the function of fibroblasts in the dermis?

A

Produce elastin, collagen and proteoglycans

16
Q

What is the neuromuscular supply to the dermis like?

A

Innervated and vascularised

17
Q

What are the three layers of the dermis?

A

Papillary, reticular and adipose

18
Q

Describe the papillary layer of the dermis

A

Contains fine, randomly organised type III collagen and elastin, and lies directly below the basement membrane of the epidermis

19
Q

What type of collagen is present in the dermis?

A

Type III collagen

20
Q

Describe the reticular layer of the dermis

A

The thickest layer densely packed with collagen providing mechanical strength

21
Q

Which dermal layer is largely responsible for the mechanical strength of the skin, and why?

A

Reticular layer of the dermis as it is densely packed with collagen

22
Q

What are adherens junctions?

A

These are more basal than tight joints and involve a cadherin receptor linked to an actin cytoskeleton

23
Q

What are desmosomes?

A

Provide a connection between intermediate filaments of the cell cytoskeletons of adjacent cells; cadherin receptor is linked to the keratin cytoskeleton

24
Q

What are tight junctions?

A

These seal adjacent epithelial cells in a narrow band just beneath their apical surface. Claudin and occluding molecules seal the intercellular space

25
Q

What are gap junctions?

A

These form intercellular pores made up of connexins

26
Q

Name four different types of cell-cell adhesions

A

Adherens, desmosome, tight junctions and gap junctions

27
Q

Name three types of glands that may be present in the skin

A

Sebaceous, eccrine sweat gland, apocrine gland

28
Q

What is a sebaceous gland?

A

Exocrine gland (secreted into duct) usually found attached to a hair follicle which produces sebum to lubricate skin

29
Q

What is acne caused by?

A

Infection of the sebaceous glands

30
Q

How are sebaceous glands affected by puberty?

A

The gland is sensitive to androgens, and enlarges at puberty as a result

31
Q

What is the role of the eccrine gland?

A

To produce watery sweat for thermoregulation

32
Q

What is the difference between eccrine and apocrine glands?

A

They are both sweat glands but apocrine glands are associated with hair follicles whereas eccrine glands are not

33
Q

Describe the structure of the eccrine sweat gland

A

Has an excretory duct and a secretory coil

34
Q

What is the role of the apocrine gland?

A

To secrete sweat associated with hair follicles, and is found in the armpit and pubic region

35
Q

Where are apocrine glands usually found?

A

Axilla and pubic regions

36
Q

What causes the smell of body odour from sweating?

A

Sweat secretion itself is odourless, but is broken down by bacteria on the skin leading to the release of volatile fatty acids which produce the odour

37
Q

What are the two types of hair follicle?

A

Vellus and terminal

38
Q

What is a villus hair follicle?

A

A hair follicle found on body hair

39
Q

What is a terminal hair follicle?

A

A hair follicle found on the scalp or with secondary sexual hair

40
Q

Which cells produce hair?

A

Keratinocytes in the matrix of the hair follicle

41
Q

What cells are involved in controlling hair growth?

A

Dermal papilla fibroblasts

42
Q

What are the three phases of the hair growth cycle?

A

Anagen, catagen and telogen

43
Q

What is the anagen phase of hair growth?

A

Active phase of hair growth

44
Q

What is the catagen phase of hair growth?

A

Regressive phase of hair growth

45
Q

What is the telogen phase of hair growth?

A

Resting phase of growth

46
Q

Where are melanocytes found?

A

In the epidermis (on basement membrane) and in the hair follicle matrix

47
Q

What is the function of melanocytes?

A

Produce melanin and package it into melanosomes (eumelain and pheomelanin) which are injected into keratinocytes to provide skin with protection against UV radiation

48
Q

Where do melanocytes inject melanin?

A

Into keratinocytes

49
Q

What are melanocytes?

A

A form of dendritic cell in the basement membrane of epidermis and in the hair follicle matrix

50
Q

What are Langerhan’s cells?

A

A form of dendritic cell in the basal and spinosum layers of the epidermis

51
Q

What is the role of Langerhans cells?

A

Act as antigen presenting cells to T cells and are a first line of defence against infection

52
Q

What are Merkel cells?

A

Involved in sensory perception of the skin (basal layer of epidermis)

53
Q

Where are Merkel cells found?

A

The basal layer of the epidermis

54
Q

What are mast cells?

A

Cells involved in the immune response by secreting histamine

55
Q

Where are mast cells found?

A

Dermis of the skin

56
Q

What is a superficial skin wound?

A

Damage to epidermis only

57
Q

What is a partial thickness skin wound?

A

Damage to epidermis and dermis

58
Q

What is a full thickness skin wound?

A

Damage to epidermis, dermis and hypodermis

59
Q

What are the three stages of wound healing?

A

Inflammation, proliferation and maturation

60
Q

How long should it take for a wound to heal?

A

Less than 6 weeks

61
Q

Outline the inflammation phase of wound healing

A

Blood clot is formed to seal wound and immune response is initiated

62
Q

Outline the proliferation phase of wound healing

A

Keratinocytes move over the wound to create a barrier, fibroblasts infiltrate wound site to produce ECM to form the new dermis and repair damaged blood vessels

63
Q

Outline the maturation phase of wound healing

A

Replace immature tissue with mature tissue