Question | Answer |
Define Repair: | body’s collective attempt to restore homeostasis (normal A & P) |
What are the general processes of Repair? | Regeneration, Healing |
Describe Regeneration: | REGENERATION: regrowth of parenchyma (function) & stroma (structure); not much scarring; usually follows mild injury. |
Describe Healing: | HEALING: broad term which implies regeneration is partial/not possible; fibrous repair = scarring |
In which repair process is repair partial, and comes with scarring? | Healing |
What are the three types of cells that need to be repaired | Labile,
Stable,
Permanent |
Describe the repair process of LABILE cells: | LABILE: capable of regeneration; short life span; replaced from stem* cells
Ex: bone marrow, intestinal/bronchial/skin epithelium |
Describe the repair process of STABLE cells: | STABLE: capable of regeneration but longer life span with slower reproductive cycle; in protected areas & very metabolically active.
Ex: liver, kidney cells |
Describe the repair process of PERMANENT cells: | PERMANENT: cannot regenerate; terminally differentiated & cannot reproduce.
Ex: cardiac & skeletal muscle, neurons (note: loss of permanent cells is usually a big deficit for the body) |
What are Tissue structures are necessary for the internal support of for repair? | Basement Membrane and Extracellular Matrix |
Define Basement Membrane? | Basement membrane: provides surface for epithelial cells to regrow |
Define Extracellular Matrix? | Extracellular matrix (ECM): Collagen elastic fibers create structural support, Use growth factors to enhance healing. Ex: Epidermal GF. Vascular endothelial GF. |
What happens if you damage Basement Membrane or Extracellular Matrix? | Basement membrane and ECM provide scaffold for regrowth and remodel to redevelop normal anatomy and function. If they are not functioning correctly, tissue may not return to normal function. |
How do Cells regenerate? | GENES code for growth factors; cells respond by mitotic activity. Ex: epidermal growth factor, vascular endothelial growth factor.
ECM influences action of growth factors and related hormones. |
If the basement membrane and ECM are damaged, Are cells receiving signal to grow? | No. The Basement Membrane and ECM have to be repaired, or the signal has to come from somewhere else, (Scarring) for there to be regeneration. |
Define Wound: | Wound = injury resulting from short term injury at a discrete site Ex: surgical incision (major) –vs- scratch on skin (minor) |
Define Fibrous repair: | Scars form when damage is extensive. |
What are the fundamentals of Wound Healing? | 1. Cell migration into wound: neutrophils, fibroblasts, macrophages, clotting factors, exudate,
2. Growth of new blood vessels: angioneogenesis
3. Scar development
a. Fibroblasts: GRANULATION TISSUE
b. ECM deposition
c. Maturation phase |
Describe Angionegenesis: | Growth of new blod vessels, capillaries, into the wound. |
What are the four steps of Angioneogenesis? | 1) Normal
2) Dissolution of Basement Membrane
3) Migration and proliferation of angioneoblastic endothelial cells
4) organization of new capillary branch |
Describe Similarities and differences of First intention and second intention.: | Healing by 1st intention: ex: straight, clean surgical incision
Healing by 2nd intention: ex: lots of necrotic tissue, wider wound, as in ulcers, infarcts, abscesses, jagged wound margins due to trauma |
Describe Abnormal wound healing: | Abnormal wound healing is impaired healing due to local/systemic factors, or an abnormal (pathologic) repair process (diabetics are notoriously slow at healing, which is why even minor wounds can be very serious.) |
What are Host factors interfering with wound healing? | Infection: Most frequent
Poor nutrition
Steroids: Make fibroblast sluggish.
Poor blood supply (diabetics)
Foreign bodies, metal fragments and debris.
Mechanical factors |
What is a wound rupture? | DEHISCENCE. wound rupture occurs most often in abdominal wounds which are under tension due to normal movements. |
What is ulceration? | Ulceration: wound surfaces not covered by epithelium will not heal properly. |
Describe Pathologic wound healing: | wound repair creates a problem, rather than solves it. |
Describe KELOID? | Pathologic wound healing. A KELOID is hyperplasia of epithelial tissue, creating a large “lump” of excess collagen. They look cancerous, but are not. |
Describe Excess granulation tissue: | localized, highly vascular area of persistent granulation tissue – looks worse than it is. Indicates a repair process which is “stuck” in the vascular stage. |