Anatomy and Physiology

The Scar Solution Natural Scar Removal

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Wounds expose components oftissue normally protected from the outside world by skin or mucous membranes. These components, including collagen, fibronectin, fibrin, and fibrinogen, provide receptors to which potential pathogens specifically attach. Collagen is a fibrous material, the main supportive protein of skin, tendons, scars, and other body structures. Fibronectin is a glycoprotein that occurs both as a circulating form and as a component of tissue, where it ties cells and other tissue substances together. Shortly after the occurrence of a wound, the soluble blood protein fibrinogen is converted to the fibrous material fibrin, thereby forming clots in the damaged vessels. This stops the flow of blood as the first step in the repair process.

Wound healing begins with the outgrowth of connective tissue cells, called fibroblasts, and capillaries from the surfaces of the wound, producing a nodular, red, translucent material called granulation tissue. In the absence of dirt or infection, granulation tissue fills the void created by the wound, contracts, and is converted to collagen that composes the scar tissue eventually covered by overlying skin or mucous membrane (figure 27.1). Sometimes in the presence of dirt or infection, the granulation tissue overgrows, bulging from the wound to form a pyo-genic granuloma.

Subepithelial -tissue

Clots forming

Subepithelial -tissue

Cells from the capillaries and subepithelial tissue cells called fibroblasts multiply, forming buds of tissue protruding into the wound.

The wound is filled with bright red granulation tissue, which differentiates into abundant new capillaries and bleeds easily.

The fibroblasts multiply, producing a dense, strong substance called collagen, the main component of scar tissue. The collagen contracts and may distort the tissue in the process; epithelium covers the repaired wound.

Figure 27.1 The Process of Wound Repair

Circulating fibrinogen is converted to fibrin, resulting in clots in the severed capillaries.

Cells from the capillaries and subepithelial tissue cells called fibroblasts multiply, forming buds of tissue protruding into the wound.

The wound is filled with bright red granulation tissue, which differentiates into abundant new capillaries and bleeds easily.

The fibroblasts multiply, producing a dense, strong substance called collagen, the main component of scar tissue. The collagen contracts and may distort the tissue in the process; epithelium covers the repaired wound.

Figure 27.1 The Process of Wound Repair

Wound Abscesses

An abscess (figure 27.2) is a localized collection of pus, composed of living and dead leukocytes, components of tissue breakdown, and infecting organisms surrounded by body tissue. There are no blood vessels in abscesses, because they have been destroyed or pushed aside. A surrounding area of inflammation and clots in adjacent blood vessels separate the abscess from normal tissue. Consequently, abscess formation helps to localize an infection and prevent its spread. Microorganisms in abscesses often are not killed by antimicrobial medications because the microorganisms cease multiplying, and active multiplication is generally required for microbial killing by the medications. In addition, the chemical nature of pus interferes with the action of some antibiotics, and many antimicrobials diffuse poorly into abscesses because of the absence of blood vessels. Microorganisms in abscesses are a poten-

, Epithelial surface

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Tissue

Leukocytes

Blood vessels dilate, and leukocytes migrate to the area of the developing infection.

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Pus forms, composed of the products of tissue cell breakdown, leukocytes, and bacteria; clotting occurs in the adjacent blood vessels.

Buildup of pressure causes the abscess to expand in the direction of least resistance; if it reaches a body surface, it may rupture and discharge its contents.

Blood clots

Figure 27.2 Abscess Formation

A pathogenic microorganism is deposited in the tissue from a wound or from the bloodstream.

Leukocytes

Blood vessels dilate, and leukocytes migrate to the area of the developing infection.

Pus forms, composed of the products of tissue cell breakdown, leukocytes, and bacteria; clotting occurs in the adjacent blood vessels.

Buildup of pressure causes the abscess to expand in the direction of least resistance; if it reaches a body surface, it may rupture and discharge its contents.

27.2 Common Bacterial Wound Infections 693

and puncture wounds. Puncture wounds caused by nails, thorns, splinters, and other sharp objects can introduce foreign material and microorganisms deep into the body. Bullets and other projectiles can carry fragments of skin or cloth contaminated with microorganisms into the tissues. Projectiles, although causing relatively small breaks in the skin, often produce extensive tissue damage because of the force with which they enter.

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