Skin, wounds and Healing

Question 1

5 Layers of epidermis

Answer 1

1) Stratum basale (deepest single layer with stem cells)
2) Stratum spinosum (Daughter cells from basale)
3) Stratum granulosum (granules/keratin formation & water resistance)
4) Stratum lucidum (thick skin only)
5) Stratum corneum (most superficial - lack a nucleus or organelles/membrane keratin filaments

Question 2

Function of langerhan’s cells

Answer 2

Immune cells - Initiate an immune response to pathogens & cancer cells

Question 3

Melanocytes

Answer 3

Located in stratum basale - droduce pigment melanin which is transferred up to keratinocytes to protect DNA from radiation

Question 4

The Dermis

Answer 4

Connective tissue beneath the epidermis. Includes the Papillary (above) & Reticular (below) dermis.

Supports the epidermis by providing blood vessels (nutrient/waste/gas exchange). Assists with sensory awareness of the environment (tactile, pain & temp).
Contains hair follicles & glands

Question 5

The hypodermis

Answer 5

Located under dermis
Holds integument to underlying tissue & permits movement of skin
Location of subcutaneous fat
(Protection/padding; Energy reservoir & Insulation)

Question 6

Sebaceous glands

Answer 6

o Produce sebum (oily secretion)

o Lubricates hair and skin

Question 7

Merocrine (eccrine) sweat glands

Answer 7

o Produce sweat (99% water + 1% electrolytes)

o Important for temperature regulation

Question 8

Apocrine sweat glands

Answer 8

o Found in the axilla, nipples, pubic & anal region

o Secretion attracts bacteria & odour

Question 9

Stages of wound healing: Inflammatory phase: immediate – 4-6 days

Answer 9

Formation of blood clot

Inflammation (incr. vascular permeability, neurtrophils and macrophages to digest debris)

Question 10

Stages of wound healing: Proliferative phase: 1 – 14 days

Answer 10

Cell devision to repolace lost tissue. The keratinocytes in stratum basale migrate and proliferate under wound to form an intact layer. There is angiogenensis (sprouting new blood vessels), migration and proliferation of fibroblasts to the wound site, and deposition of collagen by fibroblasts.

Question 11

Stages of wound healing: Maturation phase: Day 8 – 1 year

Answer 11

Granulation tissue replaced by scar tissue (Capillaries recede – white appearance)

Connective tissue is remodelled (Stronger collagen fibres, More organised & Increased) tensile strength

Question 12

Healing by first intention

Answer 12

o Clean incision
o Minimal tissue loss
o Minimal clot and scar formation

Question 13

Healing by second intention

Answer 13

o	Large wound
o	Larger clot
o	More inflammation
o	More granulation tissue 
o	Wound contraction required

Question 14

Burn depth: Superficial

Answer 14

Epidermis
Skin function & tactile/pain receptors intact
3-5 days healing
No scar potential

Question 15

Burn depth: Superficial partial-thickness

Answer 15

Epidermis and upper dermis 
Skin function is absent 
Tactile/pain receptors intact 
Healing = 21-28 days 
Scarring minimal

Question 16

Burn depth: Deep partial-thickness

Answer 16

Epidermis and most of dermis
Skin function is absent 
Tactile/pain receptors intacct but diminished 
Healing = months 
Scar potential high due to slow healing

Question 17

Burn depth: Full-thickness

Answer 17

Epidermis, dermis and hypodermis
Absent skin function, tactile & pain receptors
Healing generally req. surgery
Scar potential is variable

Question 18

First degree burn

Answer 18

Superficial

Question 19

Second degree burn

Answer 19

Superficial partial-thickness

Deep partial-thickness

Question 20

Third degree burn

Answer 20

Full Thickness

Question 21

Local response to burn injury: Zone of coagulation

Answer 21

Irreversible tissue damage

Coagulative necrosis

Question 22

Local response to burn injury: Zone of Stasis

Answer 22

Tissue is compromised and ischaemic

Outcome is variable – can worsen

Question 23

Local response to burn injury: Hyperaemia

Answer 23

Dilated blood vessels but no structural change to tissue

Will heal

Question 24

Burn Shock

Answer 24

Severe burns can cause whole body (Systemic shock)

Involves fluid shift / hypovalemia AND decreased cardiact output

Question 25

Burn Shock:

FLUID SHIFT & HYPOVOLAEMIA -

Answer 25

After injury plasma volume is reduced b/c evaporative water loss from burn and plasma shift from blood vessels into the intersitial space. This exceeds lymphatic drainage and causes oedema

Question 26

Burn Shock: Decreased Cardiac Output

Answer 26

Due to myocardial depressant factors and decreased blood volume. This causes reduced blood flow. THis means there is less O2 & nutrients but more waste/acid build-up. This causes tissue injury.