Histology of the Skin Tutorial

Question 1

name 7 basic tissue groups found in the skin

Answer 1

epithelia
hair
glands
nervous tissue
muscle fibres
connective tissue
nails

Question 2

name 3 types of epithelia that exist in the skin

Answer 2

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

Question 3

what are eccrine sweat glands?

Answer 3

found all over body except lips and genitals

regulate heat and salt loss through sweat

Question 4

what are apocrine sweat glands?

Answer 4

found only in axillae, nipples and genitals

only develop at puberty and open into hair follicles

Question 5

what are sebaceous glands?

Answer 5

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

Question 6

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

Answer 6

arrector pili muscles (smooth muscle)

attached to hair follicle and pull hair perpendicular to skin

Question 7

what connective tissue exists in the skin?

Answer 7

collagen and elastin fibres present in the dermis

Question 8

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

Answer 8

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

Question 9

what are the components of hair?

Answer 9

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

Question 10

what are nails?

Answer 10

plates of cells filled with hard keratin

Question 11

what are the components of a nail?

Answer 11

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

Question 12

what causes bullous pemphigoid?

Answer 12

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

Question 13

histological appearance of psoriasis?

Answer 13

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

Question 14

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

Answer 14

basal layer > prickle layer > granular layer > keratin layer

Question 15

thick keratin layer with gaps?

Answer 15

palm of hand or sole of foot

holes are for sweat glands

Question 16

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

Answer 16

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

Question 17

what causes toxic epidermal necrosis?

Answer 17

usually drug induced

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

Question 18

what are the possible consequences of toxic epidermal necrosis?

Answer 18

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

Question 19

list 7 requirements for healthy skin

Answer 19

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

Question 20

what are the 3 stages of healing?

Answer 20

inflammation
proliferation
tissue remodelling

Question 21

what happens in the inflammation stage?

Answer 21

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

Question 22

what is involved in the proliferation and tissue remodelling stage?

Answer 22

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

Question 23

what is involved in the tissue remodelling stage?

Answer 23

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

Question 24

what is the difference between primary and secondary intention healing?

Answer 24

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

Question 25

what are the risks with primary and secondary intention healing?

Answer 25

primary = haematoma, infection, bad suturing
secondary = infection, longer healing time

Question 26

what is a first degree burn?

Answer 26

epidermis only

Question 27

what is a second degree burn?

Answer 27

epidermis and dermis

Question 28

what is a third degree burn?

Answer 28

extends beyond dermis

Question 29

what is the definition of a chronic wound?

Answer 29

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

Question 30

what must be considered with a chronic wound?

Answer 30

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

Question 31

what is a bed sore?

Answer 31

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

Question 32

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

Answer 32

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