Tissue Repair Flashcards
Inflammation is an example of what kind of response to tissue injury?
Non-specific
What are the symptoms of acute inflammation?
Redness and warm due to increased blood flow to area
Painful - due to injury, stretch and chemical factors
Swelling/Oedema - shift of fluid from circulation into tissue spaces
Loss of Function - due to discomfort
What does inflammation do?
Acute inflammation prepares the area for healing and allowing for damaged cells and infection to be cleared away by phagocytes so the area can undergo healing
Success of tissue repair is dependent on the type of cell that is damaged. What are the three types of cell to be considered?
Labile
Stable
Permanent
What are Labile Cells?
Labile cells regenerate best, have a high rate of turnover. Examples are epithelia, found in skin, lining of respiratory tract, GI tract and blood cells.
What are stable cells?
Lower turnover. They can divide if necessary but don’t have as high a replication rate. Examples are liver cells (hepatocytes) as well as the Osteoblasts.
What are Permanent Cells?
In the adult these are incapable of producing new healthy cells. Examples include cardiac muscle cells and mature nerve cells.
Describe in simple terms the anatomy of the skin.
There is the epidermis, composed of epithelial tissue attached to the basement membrane. Below this the dermis, composed of connective tissue. The Dermis is connected by fibres to the subcutaneous layer composed of adipose and areolar tissue.
Describe the stages of wound healing.
After initial injury and acute inflammation as well as bleeding and clotting you see
- Contraction of wound - wound gets smaller
- Tissue repair/ regeneration
What is tissue regeneration?
When the wound does not penetrate below the basement membrane and so epithelia divide and replace with identical cells. No scarring.
What is tissue repair?
When the wound goes below the basement membrane into the dermis there will be both and epithelial and connective tissue response(granulation). Scarring will occur.
Describe granulation?
Blood fills wound with clot epithelia separated from each other and basement membrane
Cell division of epithelial cells using mitosis.
Macrophages, fibroblasts move to area.
Additional blood vessels develop in damaged skin
Blood clot is phagocytosed
Extracellular matrix is rdualylly deposited by fibroblasts to fill dermis gap
As epithelia cells divide they move towards centre of wound and seal gap. This dsisplaces the blot clot.
New basement membrane is secreted.
Macrophage and fibroblast numbers decrease.
Wound healed, surface integrity restored and epithelia returns to normal.
Additional capillaries are reabsorbed.
What is healing by Primary Intention?
Damage is limited - usually to epidermis.
Edges of wound close together
What is healing by Secondary Intention?
Extensive tissue loss. Epithelia and granulation tissue needs to be formed. Think animal bite or ulcer where wound is large and edges are far apart.
What factors will promote or inhibit wound healing?
- Blood supply - areas that are avascular or ischaemic will heal poorly
- Infection - prolong process of inflammation, increase length of healing time, increase chance of scar tissue
- Size of wound
- Type of wound
- Position in body
- Ionising radiation in radiography (so wounds need to heal before scan)
- foreign body in wound
- excessive movement before tensile strength is developed
- Age
- Nutrition - you need Vitamin C & Zine for collage fibres also protein
- Overall health of individual
