Wound Healing Overview

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Questions and Answers

What primarily replaces neutrophils within 48 to 96 hours during tissue repair?

Macrophages (correct)

Basophils

Eosinophils

Lymphocytes

What is a key feature of scar formation after a wound healing?

Enhanced leukocytic infiltrate

Persistence of edema

Increased vascularity

Blanching due to collagen accumulation (correct)

During wound contraction, what is primarily reduced?

The gap between dermal edges (correct)

The number of fibroblasts

The blood flow to the area

The size of the scar tissue

What type of repair tissue is formed in healing a fracture?

Specialized bone-forming tissue Signup and view all the answers

What characterizes woven bone compared to lamellar bone?

Irregular arrangement of collagen bundles Signup and view all the answers

What happens during stage 1 of fracture healing?

Haematoma formation occurs Signup and view all the answers

Which of the following occurs during the inflammation stage of fracture healing?

Increased polymorphonuclear leucocyte infiltration Signup and view all the answers

What is the primary process by which lost tissue is replaced by similar tissue?

Regeneration Signup and view all the answers

Which type of wound involves the skin being split or cracked?

Open Wound Signup and view all the answers

Labile cells have a high capacity for regeneration. Which of the following is an example of labile cells?

Surface epithelium of the skin Signup and view all the answers

Which cells are categorized as having a low level of replication but can proliferate in response to injury?

Stable cells Signup and view all the answers

Which type of cells cannot be replaced if lost due to their non-dividing nature?

Permanent cells Signup and view all the answers

What determines whether healing occurs by regeneration or repair?

Type of cells in the damaged organ Signup and view all the answers

Which of the following represents a closed wound?

Haematoma Signup and view all the answers

Which type of healing involves the formation of scar tissue?

Repair Signup and view all the answers

What effect does early motion have on wound healing?

It can cause persistent trauma. Signup and view all the answers

How does prior irradiation affect wound healing?

It blocks cell proliferation. Signup and view all the answers

What condition often contributes to delayed wound healing in older adults?

Impaired circulation. Signup and view all the answers

Which of the following is true about systemic infections?

They delay wound healing. Signup and view all the answers

What is a common complication associated with deficient scar formation?

Wound dehiscence. Signup and view all the answers

What role does diabetes mellitus play in wound healing?

It is associated with delayed wound healing. Signup and view all the answers

How do anti-inflammatory drugs affect wound healing?

They do not interfere when taken at usual doses. Signup and view all the answers

What is the result of inadequate formation of granulation tissue?

Deficient scar formation. Signup and view all the answers

Which factor is NOT associated with poor wound healing?

Excessive hydration. Signup and view all the answers

What does wound dehiscence refer to?

Inappropriate suture techniques. Signup and view all the answers

What are the two main objectives of wound healing?

Restoration of an intact epithelial surface and tensile strength of sub-epithelial tissue Signup and view all the answers

Which of the following is NOT part of the processes involved in wound healing?

Rapid cell apoptosis Signup and view all the answers

What is the primary function of growth factors in the healing process?

To stimulate cell division and proliferation Signup and view all the answers

Which source of growth factors is activated after endothelial damage?

Platelets Signup and view all the answers

What term describes the mechanical reduction in the size of a wound defect?

Wound contraction Signup and view all the answers

Which factor does NOT influence the capacity of a tissue for regeneration?

Presence of inflammatory cells Signup and view all the answers

What leads to a faster healing process during wound healing?

Wound contraction Signup and view all the answers

Which of the following processes occurs during wound healing?

Collagenization and progressive acquisition of wound strength Signup and view all the answers

What happens when wound contraction is prevented?

A large ugly scar is formed Signup and view all the answers

What defines the renewal of lost tissue with identical cells?

Regeneration Signup and view all the answers

What is the role of myofibroblasts in wound healing?

They assist in reducing the size of the wound through contraction. Signup and view all the answers

Which event occurs first within the first 24 hours after a surgical incision?

Fibrin clot forms and undergoes dehydration. Signup and view all the answers

What pattern of wound healing describes a clean surgical incision that is well approximated by sutures?

Healing by primary union Signup and view all the answers

After how many days does granulation tissue typically fill the incision space?

5 days Signup and view all the answers

What changes in the wound occur approximately two weeks post-surgery?

Scar tissue forms and collagen continues to accumulate. Signup and view all the answers

What is a characteristic of scar tissue formed after one month of wound healing?

It has an intact epidermal covering with dense connective tissue. Signup and view all the answers

Which cellular process primarily takes place during the second and third days of healing by first intention?

Epithelial cell proliferation and basal cell thickening. Signup and view all the answers

What occurs within 24-48 hours after the injury process?

Basal cells proliferate and epithelial cells migrate and deposit basement membrane components. Signup and view all the answers

Which of the following best describes healing by second intention?

It is used for heavily contaminated or irregular wounds. Signup and view all the answers

What cellular change is expected around the fifth day post-injury?

Optimal proliferation of blood vessels and collagen fibers bridging the incision. Signup and view all the answers

Study Notes

Wound Healing

Healing, in a pathological context, is the body's replacement of damaged tissue with living tissue.
A wound is a breach or defect in intact living tissue, caused by injury and accompanied by inflammation.
Wounds can be accidental or surgical.

Types of Wounds

Closed Wounds: Skin surface is intact, but underlying tissues are damaged (e.g., contusions, hematomas, Stage 1 Pressure Ulcers).
Open Wounds: Skin is split or cracked, exposing underlying tissues to the environment.

Processes of Wound Healing

Regeneration: Replacement of lost tissue with similar tissue types.
Repair (healing by scarring): Replacement of lost tissue with granulation tissue that matures into a scar.
Healing type depends on the damaged organ's cell type and stromal framework integrity.

Types of Cells

Labile Cells: High proliferative capacity, found in surface epithelium of GI tract, urinary tract, and skin; lymphoid and hematopoietic cells; excellent regeneration potential.
Stable Cells: Lower replication rates, few stem cells; can undergo rapid division in response to injury; smooth muscle cells, fibroblasts, osteoblasts, endothelial cells; good regeneration potential. Liver, endocrine glands, and renal tubular epithelium can regenerate.
Permanent Cells: Non-dividing; cannot be replaced if lost; adult neurons, striated muscle cells, lens cells.

Objectives of Wound Healing

Restore an intact epithelial surface.
Restore tensile strength of sub-epithelial tissue.
Wound healing is a complex, orderly, systematic process that involves seven processes:
Acute inflammatory response upon injury
Regeneration of native cells of tissue involved.
Proliferation and migration of native and connective tissue cells.
Synthesis of extracellular matrix (ECM) proteins.
Remodelling of connective tissue and parenchymal components.
Collagenization and progressive acquisition of wound strength.
Contraction.

Growth Factors

Healing is, in part, mediated by growth factors—low molecular weight polypeptides stimulating cell division and proliferation.
Sources of growth factors include platelets, circulating serum growth factors, macrophages, and lymphocytes recruited to the injury site.

Healing by Regeneration

Regeneration is the renewal of lost tissue by replacing lost cells with identical ones.
It involves two processes: proliferation of surviving cells to replace lost tissue and migration of surviving cells into the vacant space.
Regenerative capacity depends on tissue's proliferative ability, degree of damage, and damage severity.

Wound Contraction

Mechanical reduction in wound size, typically 70-80% of original size.
Faster healing due to reduced tissue needing replacement.
Slow and large ugly scar formation if prevented.
Myofibroblasts—features intermediate between fibroblasts and smooth muscle cells—cause contraction.
Migrate to wound site 2-3 days post-injury, decreasing wound area.

Patterns of Wound Healing

Healing by First Intention (Primary Union): Clean, uninfected surgical wounds with well-approximated sutures heal quickly. Minimal epithelial and connective tissue cell death; minimal basement membrane disruption. Immediately filled by clotted blood which dehydrates to form scab.
Healing by Second Intention: Extensive cell loss, large tissue defects; wide margins; includes infarction, inflammatory ulceration, and abscesses. Requires abundant granulation tissue, more fibrin, necrotic debris, and a significant inflammatory reaction for healing. Myofibroblasts are important for wound contraction, which is critical for healing large wounds.

Granulation Tissue

New connective tissue with microscopic blood vessels and myofibroblasts forming at wound site during healing.
Fills wound spaces; crucial for wound contraction and epithelial cell migration.

Factors Influencing Wound Healing

Local Factors: Type, size, location of wound, vascular supply, infection, movement, ionizing radiation.
Systemic Factors: Circulatory status, infection, metabolic status, nutritional deficiencies, anti-inflammatory drugs.

Complications of Wound Healing

Infection: A wound provides a portal of entry for microorganisms and delays or stops healing. Severe infection may cause extensive granulation tissue formation (proud flesh) and possible large, deforming scars.
Deficient Scar Formation: Inadequate granulation tissue formation or inability to form suitable extracellular matrix; leads to;
Wound dehiscence and incisional hernias: Improper sutures, infection; increased mechanical stress by vomiting, coughing, or ileus are risk factors.
Ulceration: Inadequate blood supply, insufficient vascularization, and persistent trauma may lead to ulceration. Commonly found in diabetics, leprosy, and tertiary syphilis.
Excessive Scar Formation: Excessive extracellular matrix deposition; leads to:
Hypertrophic scars: Raised or thickened scar tissue.
Keloids: Prominent, raised scar tissue extending beyond the wound boundaries.
Contractures: Excessive wound contraction; can restrict movement or function.

Fracture Healing

Unlike skin wounds, fracture healing involves specialized bone-forming tissue.
Bone is comprised of calcified osteoid tissue (collagen and osteomucin matrix)
Woven (immature/non-lamellar) bone shows collagen bundle irregularity.
Lamellar (adult) bone has parallel collagen bundles in sheets.
Fracture healing process occurs in seven stages, including hematoma formation, inflammation, demolition, granulation tissue formation, woven bone/cartilage formation, lamellar bone formation, and remodeling.

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Description

Explore the complex processes of wound healing, including types of wounds and cellular responses involved. This quiz provides insights into regeneration and repair mechanisms, crucial for understanding how the body heals after injury.