Skin Wound Healing Quiz

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Questions and Answers

What is the principal mechanism of repair in healing by first intention?

Collagen deposition

Granulation tissue formation

Fibrosis

Epithelial regeneration (correct)

Which of the following accurately describes a characteristic of healing by first intention?

It involves minimal disruption of tissue. (correct)

It involves significant wound contraction.

It is characterized by extensive inflammation.

It typically forms a large scar.

During the early stages of healing by first intention, which cells are primarily observed at the incision margin?

Mast cells

Fibroblasts

Macrophages

Neutrophils (correct)

What is the purpose of the fibrin clot in healing by first intention?

To act as a barrier to infection Signup and view all the answers

Which statement best describes the nature of a wound healed by first intention?

It usually has minimal cell loss. Signup and view all the answers

What percentage of their original size can large skin defects reduce to within 6 weeks through contraction?

5% to 10% Signup and view all the answers

What is a characteristic of a hypertrophic scar?

It contains a high concentration of myofibroblasts. Signup and view all the answers

What is the wound strength of a carefully sutured wound at 1 week?

10% of normal skin Signup and view all the answers

Which complication is NOT associated with tissue repair?

Complete healing without scarring Signup and view all the answers

What condition characterizes a keloid?

It continues to grow beyond the wound boundaries. Signup and view all the answers

What major change occurs by day 3 in the healing process by first intention?

Macrophages largely replace neutrophils. Signup and view all the answers

What characterizes the healing process by day 5?

Neovascularization reaches its peak. Signup and view all the answers

What occurs during the second week of healing by first intention?

Collagen accumulation continues. Signup and view all the answers

What defines the scar by the end of the first month in healing by first intention?

The scar consists mainly of cellular connective tissue. Signup and view all the answers

Healing by second intention primarily occurs in which scenario?

Extensive wounds with significant tissue loss. Signup and view all the answers

What factor leads to intensified inflammation in healing by second intention?

Increased volume of necrotic debris. Signup and view all the answers

What is a key feature of the scab formed during healing by second intention?

It is dense with fibrin and fibronectin. Signup and view all the answers

What role do myofibroblasts play in the healing process by second intention?

They mediate wound contraction. Signup and view all the answers

Study Notes

Skin Wound Healing

Two important types of tissue repair are cutaneous wound healing (skin wounds) and fibrosis in injured organs.
Cutaneous wound healing involves both epithelial regeneration and connective tissue scar formation.
Healing can occur via primary or secondary intention, depending on the wound's nature and size.

Healing by First Intention

Healing of clean, uninfected surgical incisions approximated with sutures.
Involves only focal disruption of the epithelial basement membrane.
Epithelial regeneration is the primary repair mechanism.
A small scar forms with minimal contraction.
The incisional space fills with clotted blood, followed by granulation tissue invasion and new epithelium formation.
Within 24 hours, neutrophils migrate towards the fibrin clot, basal cells exhibit increased mitosis, and epithelial cells from both edges migrate and proliferate along the dermis. Basement membrane components are deposited, forming a thin continuous epithelial layer.
By day 3, neutrophils are replaced by macrophages, granulation tissue invades the incision space, epithelial cell proliferation continues, and a thickened epidermal layer is formed.
By day 5, neovascularization peaks, granulation tissue is abundant, collagen fibrils bridge the wound, the epidermis regains normal thickness, and surface keratinization occurs.
During the second week, collagen accumulation and fibroblast proliferation continue, leukocyte infiltrate, edema, and vascularity diminish, and blanching is accomplished by collagen deposition within the incision scar and regression of vascular channels.
By the end of the first month, a cellular connective tissue scar forms, largely devoid of inflammatory cells, covered by an essentially normal epidermis, and dermal appendages destroyed during the incision are permanently lost.
The tensile strength of the wound increases with time.

Healing by Second Intention

A complex repair process involving regeneration and scarring.
Occurs in large wounds, abscesses, ulcerations, and ischemic necrosis, where tissue loss is more significant.
The inflammatory reaction is more intense, and abundant granulation tissue with large scar formation develops.
Wound contraction, mediated by myofibroblasts, follows.
Secondary healing differs from primary healing in several aspects. A larger clot or scab rich in fibrin and fibronectin forms at the wound surface, inflammation is more intense due to the greater volume of necrotic debris, exudate, and fibrin. Large defects have a greater potential for inflammatory-mediated injury.
Within 6 weeks, large skin defects may be reduced to 5-10% of their original size, primarily due to contraction.

Scar Tissue

Scars are composed of connective tissue and are largely devoid of inflammatory cells.
Dermal appendages destroyed by the incision are permanently lost.
The tensile strength of a wound increases over time.

Wound Strength

Sutured wounds have approximately 70% of normal skin strength.
Wound strength reaches about 70-80% of normal within three months.
Strength increases rapidly during the first four weeks.

Complications in Tissue Repair

Include deficient scar formation, excessive repair component formation, and formation of contractures.
Complications are seen in venous leg ulcers, arterial ulcers, pressure sores, and diabetic ulcers.

Excessive Scarring

Excessive repair component formation can lead to hypertrophic scars and keloids.
Hypertrophic scars are raised scars that contain abundant collagen and myofibroblasts, and typically regress over several months.
Keloids are scars that grow beyond the original wound boundaries and do not regress.

Fibrosis in Parenchymal Organs

Excessive deposition of collagen and other ECM components in internal organs.
Chronic diseases, infections, and immunologic reactions are potent inducing factors.
Fibrosis can lead to organ dysfunction or failure.
Key cytokines involved in fibrosis are TGF-β.
Cell death (necrosis/apoptosis) and reactive oxygen species (ROS) triggers fibrosis.
Myofibroblasts are a major source of collagen in lungs and kidneys, while stellate cells are important in the liver.

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Description

Test your knowledge on the processes involved in skin wound healing, including cutaneous repair and healing by first intention. Explore the mechanisms of epithelial regeneration and scar formation, as well as the timeline of healing events. This quiz will help reinforce your understanding of wound healing dynamics.