Patho-Tissue Regeneration and Rpair

Question 1

Goal of tissue regeneration and Repair

Answer 1

Cover the wound
Clear the debris
Restore the structural and functional integrity of the injured area

Question 2

Inflammatory phase

Answer 2

Acute inflammatory response
Cover the wound: Hemostasis (platelets released; blood vessels constrict); thrombus forms
Clean the debris: macrophages; remove necrotic tissue

Question 3

Proliferative phase

Answer 3

Restore structural integrity; provisional matrix (granulation tissue)
Rebuild: basement membrane; connective tissue

Question 4

Remodeling phase

Answer 4

Resolution
Repair
Regeneration
Remodeling
Maturation of cells
Degradation of provisional matrix

Question 5

Restoring Functional Integrity

Answer 5

1. Resolution
2. Regeneration
3. Replacement

Question 6

Resolution

Answer 6

Healing response to mild injury

Minimal disruption to cells

Question 7

Regeneration

Answer 7

Can only occur in those cells that undergo mitotic division
Accomplished by:
Proliferation (growth and reproduction)
Differentiation (cells mature and become more specialized)
Diapedesis (migration of nearby cells)
Depends on cell type
Epithelial (skin, linings of blood vessels, mucous membranes) readily divide and regenerate

Question 8

connective tissue regeneration

Answer 8

1. bone (active tissue heals rapidly
2. cartilage (regeneration possible but slow)
3. Tendons and ligaments-regeneration possible but slow
4. blood- cells actively regenerate

Question 9

muscle regeneration

Answer 9

1. smooth-possible (particularly GI tract)
2. Cardiac-damaged muscle replaced by connective tissue
3. Skeletal-connective tissue replaces severely damaged muscle; some regeneration in moderately damaged muscle

Question 10

nerve regeneration

Answer 10

1. neuron-generally nonmitotic; do not replicate and replace themselves if irreversibly damaged
2. Gilial cells regenerate, scar tissue often forms when neurons are damaged

Question 11

Replacement

Answer 11

Through production of scar tissue
Occurs in extensive wounds
When regeneration is not possible
When permanent cells are damaged, the functional tissue is replaced with connective tissue

Question 12

Healing Process

Answer 12

Objective of the healing process is to fill the gap created by tissue destruction to restore the structural continuity
Primary healing: small, clean wound
Secondary healing: great loss of tissue with contamination

Question 13

primary intention healing process

Answer 13

Primary intention-takes place when wound margins are nearly approximated, such as in a surgical incision or a paper cut. Processes include three phases:
Initial phase
Granulation phase
Maturation phase and scar contraction

Question 14

initial phase of healing process

Answer 14

Initial phase (3-5 days): approximation of incision edges; migration of epithelia cells; clot serving as meshwork for starting capillary growth

Question 15

Granulation phase of healing process

Answer 15

Granulation (5 days to 4 weeks): migration of fibroblasts; secretion of collagen; abundance of capillary buds; fragility of wound-fibroblastic, proliferative, reconstructive

Question 16

Scar contracture of healing phase

Answer 16

Scar contracture (7 days to several months): remodeling of collagen; strengthening of scar – fibroblasts are immature connective tissue cells that migrate into the healing site and secrete collagen

Question 17

Secondary intension

Answer 17

Wounds that occur from trauma, ulceration and infection have large amounts of exudate and wide, irregular wound margins with extensive tissue loss. Wounds may have edges that can be approximated
Inflammatory reaction may be greater than in primary intention. Results in more debris cells, and exudate. The debris may have to be cleaned away (debrided) before healing can take place
Essentially the same process as in primary intention
In some instances a primary intention may become infected, creating additional inflammation-wound may re-open, and healing by secondary intention takes place. Greater defect and a gaping wound edges than in primary intention
Healing and granulation take place from edges inward and from the bottom of the wound upward until the defect is filled
There is more granulation tissue, and the result is a much larger scar

Question 18

tertiary intension

Answer 18

Delayed primary intention
Healing occurs with delayed suturing of a wound in which two layers of granulation tissue are sutured together
Occurs when a contaminated wound is left open and suture closed after the infection is controlled.
Also occurs when a primary wound becomes infected, is opened and allowed to granulated and is then sutured
Usually results in a larger and deeper scar than primary or secondary intention

Question 19

Factors That Delay Wound Healing

Answer 19

Nutritional deficiencies (vitamin C, protein and zinc)
Inadequate blood supply – impaired blood flow and oxygen delivery
Corticosteroid drugs
Infection
Smoking
Mechanical friction on wound
age
Obesity
Diabetes mellitus
Poor general health- impaired inflammatory and immune responses
Wound separation
Anemia
Foreign bodies

Question 20

Complications of Healing

Answer 20

Hypertrophic scars-inappropriately large, raised and hard
Keloid formation-greater protrusion of scar tissue that extends beyond the wound edges and may form tumor-like masses
Contracture-necessary for healing-process may become abnormal where there is excessive contracture resulting in deformity or contracture
Dehiscence-separation and disruption of previously joined edges
Excess granulation tissue-may protrude above the surface of the healing wound
Adhesions-bands of scar tissue between or around organs