Histology of the Skin Tutorial Flashcards

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1
Q

name 7 basic tissue groups found in the skin

A
epithelia
hair
glands
nervous tissue
muscle fibres
connective tissue
nails
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2
Q

name 3 types of epithelia that exist in the skin

A

stratified squamous - lines epidermis
simple squamous - endothelium lining blood vessels
glandular epithelium - sweat and sebaceous glands

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3
Q

what are eccrine sweat glands?

A

found all over body except lips and genitals

regulate heat and salt loss through sweat

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4
Q

what are apocrine sweat glands?

A

found only in axillae, nipples and genitals

only develop at puberty and open into hair follicles

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5
Q

what are sebaceous glands?

A

masses in the dermis, derived from the epidermis, that secrete sebum into hair follicle to coat hair and skin
not present in palms or soles

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6
Q

what muscle fibres exist in the skin and what do they do?

A

arrector pili muscles (smooth muscle)

attached to hair follicle and pull hair perpendicular to skin

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7
Q

what connective tissue exists in the skin?

A

collagen and elastin fibres present in the dermis

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8
Q

what 3 types of nervous tissue is are present in the skin?

A

meissners corpuscles = tactile sensation (in dermis)
Pacinian corpuscles = deep pressure (in dermis)
free nerve endings = for pain (in epidermis basal layer)

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9
Q

what are the components of hair?

A

follicle = invagination of epidermis
medulla = contains soft keratin
cortex = hard keratin
bulb = bulge at base containing papilla and hair matrix - vascular channels and keratin producing cells
melanocytes sit above papilla giving hair colour

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10
Q

what are nails?

A

plates of cells filled with hard keratin

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11
Q

what are the components of a nail?

A

nail plate - sits on nail bed
matrix - cells divide and produce keratin
cuticle - extension of skin fold covering nail root
hyponychium - secures free nail edge

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12
Q

what causes bullous pemphigoid?

A

problem with dermo-epidermal junction meaning the epidermis and dermis cant stick together and fluid builds up in between

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13
Q

histological appearance of psoriasis?

A

dense nuclei at keratin layer as there is no granular layer and the cells don’t have enough time to differentiate

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14
Q

what are the 4 layers of the epidermis, from bottom to top?

A

basal layer > prickle layer > granular layer > keratin layer

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15
Q

thick keratin layer with gaps?

A

palm of hand or sole of foot

holes are for sweat glands

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16
Q

what are the signs and symptoms of toxic epidermal necrosis (skin failure)?

A

widespread rash with blisters and sheets of skin falling off following antibiotic treatment

17
Q

what causes toxic epidermal necrosis?

A

usually drug induced

death of keratinocytes results in detachment at dermo-epidermal junction causing skin to detach in large necrotic sheets

18
Q

what are the possible consequences of toxic epidermal necrosis?

A

loss of thermoregulation
increased infection risk
failure of homeostatic function - high/electrolyte loss = hypotension = renal failure
cardiovascular instability

19
Q

list 7 requirements for healthy skin

A
water/hydration
nutrition
good vascular supply
functioning immune system
hygiene 
limited sun damage
vitamin D
20
Q

what are the 3 stages of healing?

A

inflammation
proliferation
tissue remodelling

21
Q

what happens in the inflammation stage?

A

platelets form clot and release inflammatory mediators
leukocytes phagocytose bacteria in wound sites
inflammation decreases as keratinocyte proliferation and new tissue formation become predominant

22
Q

what is involved in the proliferation and tissue remodelling stage?

A

cells divide to re-epithelialize the wound surface
granulation tissue formation
fibroblasts lay down matrix and contract wound
endothelial cells develop into new vessels
thus, new tissue is formed

23
Q

what is involved in the tissue remodelling stage?

A

new tissue is converted into mature scar tissue over months

fibroblasts lay down collagen to improve tensile strength of scar and restore normal dermal matrix

24
Q

what is the difference between primary and secondary intention healing?

A

primary intention = acute wound (e.g surgical wound)is closed by bringing the edges together
secondary = acute wound is left to heal on its own

25
Q

what are the risks with primary and secondary intention healing?

A
primary = haematoma, infection, bad suturing
secondary = infection, longer healing time
26
Q

what is a first degree burn?

A

epidermis only

27
Q

what is a second degree burn?

A

epidermis and dermis

28
Q

what is a third degree burn?

A

extends beyond dermis

29
Q

what is the definition of a chronic wound?

A

a wound that does not heal within 3 months
often exhibit a surface slough (yellow/green mixture of dead cells, polymorphs and bacteria)
E.g - diabetic foot ulcer

30
Q

what must be considered with a chronic wound?

A
infection
blood supply
nutrition
venous return
trauma/pressure
systemic diseas (diabetes, anaemia etc)
31
Q

what is a bed sore?

A

erosion and ulceration of skin due to prolonged pressure over a bony area causing a lack of blood flow to the area as well as friction from bedding/clothing or bodily fluids

32
Q

what are the stages in the development of a bed sore?

A
  1. reddening of skin
  2. swollen, painful blisters, upper layers of skin begin to die
  3. sore breaks through skin and extends into deeper layers, creating deep ulcers prone to infection
  4. sore extends past the skin and into fat, muscle and bone
    black dead tissue may appear