Module 4 - Chapter 6 - Wound Healing Flashcards
What is the ultimate goal of the inflammatory process?
the ultimate goal of inflammation is healing and repair.
What conditions favor the most favorable outcome of inflammation, which is a return to normal structure and function?
The most favorable outcome occurs when the damage is minor, no complications arise, and the destroyed tissues are capable of regeneration. This often happens in tissues like the skin, intestines, and liver.
What is the term for the process of restoring normal structure and function in tissues?
The process of restoring normal structure and function in tissues is called “resolution.” It may take up to two years to complete.
What role does IL-10 play in the resolution of inflammation?
Local production of IL-10 is believed to play a critical role in the resolution of inflammation.
When may resolution not be possible in the context of inflammation?
Resolution may not be possible in cases of extensive damage, tissues that are incapable of regeneration, infections leading to abscess or granuloma formation, or the persistence of fibrin in the lesion.
What happens when resolution is not possible in inflammation?
When resolution is not possible, repair takes place. Repair involves replacing damaged tissue with scar tissue.
What is the primary component of scar tissue, and what function does it serve?
Collagen is the main component of scar tissue, and it fills in the lesion, restoring most of the tissue’s strength.
What limitation does scar tissue have compared to the original tissue it replaces?
Scar tissue, primarily composed of collagen, cannot carry out the same physiological functions as the original tissue. This can result in a loss of function in the affected area.
What are the three processes involved in wound healing?
Wound healing involves processes that (1) fill in, (2) seal, and (3) shrink the wound.
what is the primary difference between primary intention and secondary intention healing?
Primary intention healing occurs in clean incisions with minimal tissue loss and closely apposed wound edges, while secondary intention healing occurs in open wounds with significant tissue loss.
What is the primary mechanism of wound healing in clean incisions with minimal tissue loss?
In clean incisions with minimal tissue loss, wound healing primarily involves collagen synthesis.
What are the characteristics of primary intention healing?
Primary intention healing involves minimal sealing (epithelialization) and shrinkage (contraction) and is relatively fast.
In what type of wounds does secondary intention healing occur?
Secondary intention healing occurs in open wounds with significant tissue loss, such as stage IV pressure ulcers.
What are the key components of secondary intention healing, and how does it differ from primary intention healing?
Secondary intention healing involves a longer process of epithelialization, scar formation, and contraction, and it requires extensive tissue replacement, which is not the case in primary intention healing.
Which types of cells can fully regenerate as part of the wound healing process?
Epithelial, hepatic (liver), and bone marrow cells are capable of complete mitotic regeneration in a process known as compensatory hyperplasia.
What happens when fibrous connective tissues heal?
In fibrous connective tissues like joints and ligaments, normal healing replaces the original tissue with new tissue that may have a different structure and function.
What are the three phases of wound healing, and in what order do they occur?
Wound healing occurs in three phases: (1) inflammation, (2) proliferation and new tissue formation, and (3) remodeling and maturation.
What is the role of the inflammation phase in wound healing?
The inflammation phase is the initial stage, involving the body’s immune response and tissue cleaning.
What processes are involved in the proliferation and new tissue formation phase of wound healing?
In the proliferation and new tissue formation phase, new blood vessels and connective tissue are produced, and the wound begins to close.
What occurs during the remodeling and maturation phase of wound healing?
In the remodeling and maturation phase, the healed tissue is reshaped and strengthened over time.
What is Phase I in wound healing, and when does it begin?
Phase I is the inflammatory phase of wound healing, and it begins almost immediately after an injury.
What are the key events that occur during the inflammatory phase of wound healing?
During the inflammatory phase, key events include coagulation (hemostasis), the infiltration of cells like platelets, neutrophils, and macrophages, and the formation of a fibrin mesh as a scaffold for healing.
What role do platelets play in the inflammatory phase of wound healing?
Platelets contribute to clot formation and release growth factors that initiate the proliferation of undamaged cells.
What is the function of neutrophils during the inflammatory phase?
Neutrophils help clear the wound of debris and bacteria, contributing to the initial cleaning of the wound.
Why are macrophages essential to the wound healing process?
Macrophages are crucial because they clear debris, release wound healing mediators and growth factors, recruit fibroblasts (cells important for tissue repair), and promote the formation of a new blood supply (angiogenesis) as the wound healing process progresses.
when does Phase II of wound healing, known as the proliferative phase, typically begin?
Phase II, the proliferative phase of wound healing, usually starts around 3 to 4 days after the injury.
What is the main change that occurs during the proliferative phase concerning the clot in the wound?
The fibrin that initially sealed the wound is gradually replaced by either normal tissue or scar tissue during the proliferative phase.
What are the key events that characterize the proliferative phase of wound healing?
The proliferative phase involves macrophage invasion, recruitment and proliferation of fibroblasts, collagen synthesis, epithelialization, wound contraction, and cellular differentiation.
How do platelets and macrophages contribute to wound healing during the proliferative phase?
Platelets help with clot formation and release growth factors that stimulate cell growth. Macrophages play a central role in clearing debris, releasing healing mediators, recruiting fibroblasts, and promoting the formation of new blood vessels.
What are some of the biochemical mediators secreted by macrophages during wound healing?
Macrophages secrete substances like TGF-β, angiogenesis factors (e.g., VEGF, FGF-2), and matrix metalloproteinases (MMPs) to stimulate various aspects of healing.
What is granulation tissue, and why does it have a red, granular appearance?
Granulation tissue grows into the wound from healthy tissue and contains invasive cells, new lymphatic vessels, and new capillaries. It appears red and granular due to these new blood vessels.
What is epithelialization, and why is moisture important for it during skin wound healing?
Epithelialization is the process by which epithelial cells grow into the wound from surrounding tissue. Keeping the wound moist prevents the formation of a scab, facilitating faster epithelialization.
Why are fibroblasts important during wound healing, and what stimulates their activity?
Fibroblasts are crucial because they secrete collagen and other connective tissue proteins. Macrophage-derived TGF-β stimulates fibroblasts to proliferate and deposit these proteins.
What is the significance of collagen in wound healing, and what elements are required for proper collagen polymerization?
Collagen is a vital structural protein in wound healing. Proper collagen polymerization requires iron, vitamin C (ascorbic acid), and oxygen. The absence of any of these hampers wound healing.
What are myofibroblasts, and what role do they play in wound healing?
Myofibroblasts are specialized cells responsible for wound contraction. They have characteristics of both smooth muscle cells and fibroblasts, helping to close wounds through contraction.
When does wound contraction become noticeable during wound healing?
Wound contraction becomes noticeable approximately 6 to 12 days after the injury.
When does Phase III, known as the remodeling and maturation phase of wound healing, typically begin?
phase III begins several weeks after the injury and can last up to 2 years.
Flashcard 2
What processes continue during the remodeling and maturation phase of wound healing?
During this phase, cellular differentiation continues, scar formation and remodeling occur, and tissue regeneration and wound contraction continue.
What is the primary cell involved in tissue remodeling during this phase?
Fibroblasts are the major cells involved in tissue remodeling during the remodeling and maturation phase. They deposit collagen into an organized matrix.
How does scar tissue change during the remodeling and maturation phase?
Scar tissue contracts, and capillaries in the scar tissue gradually disappear, leaving the scar avascular (without blood vessels).
When does scar tissue gain a significant portion of its maximal strength during the remodeling and maturation phase?
Within 2 to 3 weeks after the maturation phase begins, the scar tissue has gained about two-thirds of its eventual maximal strength.
How long can the remodeling and maturation phase persist?
The remodeling and maturation phase can persist for years and is aimed at recovering normal tissue structure.
What factors can lead to dysfunctional wound healing?
Dysfunctional wound healing can result from factors such as ischemia, excessive bleeding, obesity, excessive fibrin deposition, diabetes, wound infection, inadequate nutrients, medications, and tobacco smoke.
How does ischemia affect wound healing?
Ischemia, or oxygen deprivation, can lead to cellular death and infection, prolonging inflammation and delaying healing. It reduces energy production and impairs collagen synthesis and tissue strength.
Why does excessive bleeding prolong wound healing?
Large blood clots increase the space granulation tissue must fill and serve as barriers to oxygen diffusion. Accumulated blood can promote infection, prolong inflammation, and inhibit inflammation due to vessel constriction.
How does obesity affect wound healing?
Obesity can delay wound healing due to impaired leukocyte function, increased risk of infection, decreased growth factors, elevated proinflammatory cytokine levels, dysregulated collagen synthesis, and decreased angiogenesis.
What is the impact of excessive fibrin deposition on wound healing?
Excessive fibrin deposition can lead to the formation of fibrous adhesions, which can bind organs together and distort or strangulate them.
Why are individuals with diabetes at risk for prolonged wound healing?
Diabetes can lead to ischemic wounds due to microvascular issues, altered hemoglobin with reduced oxygen release, suppression of macrophages, and increased infection risk.
How do pathogens contribute to delayed wound healing?
Pathogens infiltrating a wound can damage cells, stimulate ongoing inflammation, deplete nutrients, and hinder the healing process.
Why is optimal nutrition crucial for wound healing?
Adequate nutrition is vital because it supports increased metabolic needs during healing. Nutrients like glucose, proteins, vitamins (A and C), and minerals (iron, zinc, etc.) are essential for various healing processes.
How do medications like antineoplastic agents, NSAIDs, and steroids affect wound healing?
These medications can delay wound healing by inhibiting cell division, angiogenesis, and immune responses, among other effects.
What are hypertrophic scars and keloids?
Hypertrophic scars are raised but stay within the wound’s original boundaries and tend to regress. Keloids are raised scars that extend beyond the original wound boundaries, invade surrounding tissue, and often recur after surgical removal.
Is there a genetic predisposition to keloid formation, and in which population is it more prevalent?
Yes, there is a familial tendency for keloid formation. Keloids are more prevalent in Black individuals compared to White individuals.
What is wound disruption, and when does it typically occur after suturing?
Wound disruption, or dehiscence, is when a sutured wound pulls apart. It often occurs 5 to 12 days after suturing when collagen synthesis is at its peak.
What are some potential causes of wound dehiscence?
Wound dehiscence can result from factors such as infection or sutures breaking due to excessive strain.
How does obesity increase the risk of wound dehiscence?
Obesity increases the risk because adipose (fat) tissue can be challenging to suture effectively.
What are common signs and symptoms of wound dehiscence?
Common signs include increased serous drainage from the wound and the patient’s perception that “something gave way.”
What is the recommended course of action if wound dehiscence occurs?
Wound dehiscence requires immediate surgical attention to address the complication and prevent further issues.
What is the role of wound contraction in the healing process?
Wound contraction is necessary for healing, but excessive contraction can lead to deformities or contractures in scar tissue.
What types of injuries or conditions are particularly susceptible to contracture development?
Skin burns, especially those near joints, are highly susceptible to contracture development, which can restrict joint movement.
Can contractures also occur internally? Provide examples.
Yes, internal contractures can occur. Examples include duodenal strictures from peptic ulcers, esophageal strictures from chemical burns (like lye ingestion), and abdominal adhesions resulting from surgery, infection, or radiation.
How can contractures impact cirrhosis of the liver?
Contractures in cirrhosis can constrict vascular flow and contribute to portal hypertension and esophageal varices.
What are some strategies to address excessive skin contractures?
Approaches include proper positioning, range-of-motion exercises, and occasionally surgery.
What is a common method to release internal contractures?
Surgery is a common approach to release internal contractures and improve the affected area’s function.
How do newborns acquire physiological immunity?
Newborns acquire physiological immunity from their mothers through the placenta and breast milk.
What is a characteristic of the inflammatory responses in newborns?
Newborns have temporarily depressed inflammatory responses.
Why are neutrophils in newborns incapable of chemotaxis?
Neutrophils in newborns lack fluidity in their plasma membrane, which makes them incapable of chemotaxis.
What component of the immune system is diminished in newborns, especially in premature ones?
Complement levels, particularly components of the alternative pathways like factor B, are diminished in newborns, especially in premature ones.
Are monocyte/macrophage numbers normal in newborns?
Yes, monocyte/macrophage numbers are normal in newborns, but their chemotaxis is delayed.
What infections are newborns prone to due to chemotactic defects?
Newborns are prone to infections associated with chemotactic defects, such as cutaneous abscesses caused by staphylococci and cutaneous candidiasis.
In what situations do newborns have diminished oxidative and bacterial responses?
Newborns with in utero infection or respiratory insufficiency may have diminished oxidative and bacterial responses.
When are newborns at risk of severe sepsis and meningitis?
Newborns are at risk of severe overwhelming sepsis and meningitis when infected by bacteria against which no maternal antibodies are present.
How does breast milk contribute to newborn immunity?
Breast milk helps establish the gut microbiome in newborns.
What effect does the method of delivery have on newborns’ gut microbiome?
Newborns delivered by Caesarean section may have reduced gut microbial diversity.
Do older individuals have normal numbers of innate immune cells?
Yes, older individuals have normal numbers of cells in their innate immune system.
What is a common characteristic of innate immune cells in older individuals?
Innate immune cells in older individuals may have diminished function, including decreased phagocytic activity and altered cytokine synthesis.
Why is the incidence of chronic inflammation higher in older individuals?
The higher incidence of chronic inflammation in older individuals may be related to increased production of proinflammatory mediators.
What health conditions can put older individuals at risk for impaired healing and infection?
Chronic illnesses like diabetes mellitus, peripheral vascular disease, or cardiovascular disease can put older individuals at risk for impaired healing and infection, along with decreased phagocytosis.
How can medication use affect the healing process in older individuals?
Medication use, particularly anti-inflammatory steroids, may interfere with the healing process in older individuals.
What age-related change contributes to decreased protection against injury in older individuals?
Aging often leads to a loss of subcutaneous fat, reducing layers of protection against injury.
How does atrophied epidermis in older individuals impact wound healing?
Atrophied epidermis, including underlying capillaries, decreases perfusion and increases the risk of hypoxia in the wound bed in older individuals.
