Stages of tissue injury and repair Flashcards
What are the 4 stages of tissue repair?
bleeding, inflammation, repair and remodeling
Definition and purpose of inflammation
reaction of body tissues to protect, localize and fight either an acute or chronic irritant or injury and to prepare for healing
Purpose of inflammation?
protective mechanism to rid body of the irritant and to promote repair and healing of damaged tissues.
What are the signs and symptoms of inflammation?
heat, readness, swelling, pain and loss of function.
What accompanies every injury?
some amount of tissue damage.
what are the three phases of tissue injury and repair?
1) acute inflammatory, 2) repair , 3) remodeling
what can the repair of injury sometimes involve?
regeneration of native cells, but mostly scar tissue.
What is the purpose of the Phase 1 inflammatory response?
defend against infection, dispose of dead tissues, imobilize. compartementalize
three physiological events in acute inflammation?
neurologic, hemodynamic and cellular
What are the neurologic evens of Phase 1, inflammation?
initial vasoconstrictions (30sec) followed by gradual vasodilation, bleed may start then.
Hemodynamic events of phase 1, inflammation?
vasoconstriction, vasodilation, slowing of flood, margination of leukosites, permeable changes.
Cellular events of phase 1, inflammation?
mast cells (histamine) circulating leukocytes, monocytes and mactophages (5 hours post injury)
Phase 1 inflammation chemical events?
More than 180 different chemicals., but also serotonin, heparin, histamine, bradykinins, prostoglandins.
Phase 2, what is the purpose?
Regenerate or repair lost and damaged tissues
Time frame of phase 1?
hours to a few days
How does tissue repair happen for Phase 2?
Regenerate native cells in some tissue, in others repairs are made with connective tissue
What tissues regenerate native cells?
skin, bone, lymph, liver, kidney
What tissues repair with connective tissue and scar formation?
Musculoskeletal tissues.
Time frame of phase 2?
begins in 24 hours, lasts between 2 days and 6 weeks.
What is the halmark of the phase 2?
Physiological events: synthesis and deposition of collagen.
cells envolved in the repair stage?
macrophages, granulation tissue, fibroblasts.
when does wound contract in phase @?
4 days from injury but it can take 6 - 12 months reducing wound size 5-10%
What is the purpose of phase 3?
reorganiation of collagen so it can withstand stress.
How long does stage 3, remodeling take?
8-10 week window for remodeling, will still only be 80% as strong as original.
What are the three types of factors that delay healing?
Intrinsic, extrinsic, iatrogenic
What is an intrinsic factor to delay healing?
age, nutrition, nature of injury, level of damage.
Extrinsic factors that can delay healing?
degree of immobilization, infection, immune levels, stress
Iatrogenic factors that can delay healing?
medications, ischemia
How well does cartilage heal?
limited healing because of poor vascularity
How weel do ligaments heal?
slow because of poor vascularity, may slowly form scar
How well does skeletal muscle heal?
same rate as vascular tissues, forms scars.
Nerve tissue, how well does it heal?
peripheral nerves - fair healing depending on damage, CNS nerves heal poorly
Can phycosocial factor affect healing?
Yes, can complicate and delay healing.
