Flashcards in Acute Injury Deck (26):
What is the difference between acute and chronic injury?
Acute is less than 6 weeks, chronic is more than 6 weeks
What are the 3 stages of tissue healing?
Stage 1: Inflammation
Stage 2: Organisation, granulation
Stage 3: Regeneration, fibrosis, remodelling
What is fibrosis?
When does tissue repair occur?
When barriers are penetrated, e.g. puncture, crush, tear, sheering, bruise, burn
What are the two methods of tissue repair?
- Regeneration: Same kind of tissues replace destroyed tissues, original function restored
- Fibrosis: Connective tissue replaces destroyed tissue, original function lost
What occurs during the inflammation stage of tissue healing?
- Release of inflammatory chemicals (kinins)
- Dilation of blood vessels
- Increase in vessel permeability
During inflammation, why do the blood vessels become more permeable?
To allow white blood cells, fluid, clotting proteins and other plasma proteins to seep into the injured area
What are the functions of the inflammatory response?
- Prevents spread of damaging agents
- Disposes of cell debris and pathogens
- Alerts adaptive immune system
- Sets the stage for repair
How does inflammation begin?
Chemicals are released into ECF by injured tissues, immune cells & blood proteins
What cells bear toll-like receptors (TLRs)?
Macrophages & epithelial cells of boundary tissues
How many types of TLRs recognise specific classes of infecting microbes?
What do activated TLRs trigger release off?
Cytokines that promote inflammation
What are inflammatory mediators & what do they cause?
Kinins, prostaglandins & complement - dilate local arteriols, make capillaries leaky, attract leukocytes
What does swelling (oedema) cause?
Pushes on nerve endings causing pain, moves foreign materials into lymphatic vessels, delivers clotting proteins and complement
What do clotting factors form & what is its function?
Fibrin mesh - scaffold for repair, isolates injured area so invaders cannot spread
What are the cardinal signs of acute inflammation?
Redness, heat, swelling, pain & sometimes impairment of function
What are the main components of organisation & granulation?
New nerve tissue, new capillary beds & fibroblasts/myofibroblasts
What do myofibroblasts do?
Pull the edges of a wound together
In stage 2 of tissue healing, what does organisation achieve & how?
Restores blood supply
- Blood clot is replaced with granulation tissue
- Epithelium regenerates
- Fibroblasts produce collagen fibres to bridge the gap
- Debris phagocytosed
- New blood vessels & nerve endings grow together
What occurs during stage 3 of tissue healing (regeneration & fibrosis)?
- Scab detaches
- Fibrous tissue matures
- Results in fully regenerated epithelium with underlying scar tissue
What tissues regenerate extremely well?
Epithelial, bone, areolar connective, dense irregular connective
What tissues have moderate regenerating capacity?
Smooth muscle, dense regular connective
What tissues have virtually no functional regenerative capacity?
Cardiac, nervous tissue of brain & spinal cord
What are the healing response time frames?
- Inflammation: 1 hour - 4 days
- Organisation, granulation: 12 hours - 3 weeks
- Regeneration, fibrosis, remodelling: 3 days - 18 months
What are the benefits of RICE?
- Prevents re-bleeding/further injury
- Allows platelets, myofibroblastts to hold position
- Relieves pain
- Decreases circulation
- Decreases bleeding
- Decreases inflammation
- Decreases swelling