Skin, wounds and Healing Flashcards
5 Layers of epidermis
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
Function of langerhan’s cells
Immune cells - Initiate an immune response to pathogens & cancer cells
Melanocytes
Located in stratum basale - droduce pigment melanin which is transferred up to keratinocytes to protect DNA from radiation
The Dermis
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
The hypodermis
Located under dermis
Holds integument to underlying tissue & permits movement of skin
Location of subcutaneous fat
(Protection/padding; Energy reservoir & Insulation)
Sebaceous glands
o Produce sebum (oily secretion)
o Lubricates hair and skin
Merocrine (eccrine) sweat glands
o Produce sweat (99% water + 1% electrolytes)
o Important for temperature regulation
Apocrine sweat glands
o Found in the axilla, nipples, pubic & anal region
o Secretion attracts bacteria & odour
Stages of wound healing: Inflammatory phase: immediate – 4-6 days
Formation of blood clot
Inflammation (incr. vascular permeability, neurtrophils and macrophages to digest debris)
Stages of wound healing: Proliferative phase: 1 – 14 days
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.
Stages of wound healing: Maturation phase: Day 8 – 1 year
Granulation tissue replaced by scar tissue (Capillaries recede – white appearance)
Connective tissue is remodelled (Stronger collagen fibres, More organised & Increased) tensile strength
Healing by first intention
o Clean incision
o Minimal tissue loss
o Minimal clot and scar formation
Healing by second intention
o Large wound o Larger clot o More inflammation o More granulation tissue o Wound contraction required
Burn depth: Superficial
Epidermis
Skin function & tactile/pain receptors intact
3-5 days healing
No scar potential
Burn depth: Superficial partial-thickness
Epidermis and upper dermis Skin function is absent Tactile/pain receptors intact Healing = 21-28 days Scarring minimal
Burn depth: Deep partial-thickness
Epidermis and most of dermis Skin function is absent Tactile/pain receptors intacct but diminished Healing = months Scar potential high due to slow healing
Burn depth: Full-thickness
Epidermis, dermis and hypodermis
Absent skin function, tactile & pain receptors
Healing generally req. surgery
Scar potential is variable
First degree burn
Superficial
Second degree burn
Superficial partial-thickness
Deep partial-thickness
Third degree burn
Full Thickness
Local response to burn injury: Zone of coagulation
Irreversible tissue damage
Coagulative necrosis
Local response to burn injury: Zone of Stasis
Tissue is compromised and ischaemic
Outcome is variable – can worsen
Local response to burn injury: Hyperaemia
Dilated blood vessels but no structural change to tissue
Will heal
Burn Shock
Severe burns can cause whole body (Systemic shock)
Involves fluid shift / hypovalemia AND decreased cardiact output
Burn Shock:
FLUID SHIFT & HYPOVOLAEMIA -
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
Burn Shock: Decreased Cardiac Output
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.
