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Skin Healing
Protection from mechanical injury, chemical hazards, and bacterial invasion is provided by the skin because the epidermis is relatively thick and covered with keratin. Secretions from sebaceous glands and sweat glands also benefit this protective barrier. In the event of an injury that damages the skin's protective barrier, the body triggers a response called wound healing. After hemostasis, inflammation white blood cells, including phagocytic macrophages arrive at the injury site. Once the invading microorganisms have been brought under control, the skin proceeds to heal itself. The ability of the skin to heal even after considerable damage has occurred is due to the presence of stem cells in the dermis and cells in the stratum basale of the epidermis, all of which can generate new tissue. When an injury extends through the epidermis into the dermis, bleeding occurs and the inflammatory response begins. Clotting mechanisms in the blood are soon activated, and a clot of scab is f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemical Hazard
A chemical hazard is a (non-biological) substance that has the potential to cause harm to life or health. Chemicals are widely used in the home and in many other places. Exposure to chemicals can cause acute or long-term detrimental health effects. There are many types of hazardous chemicals, including neurotoxins, immune agents, dermatologic agents, carcinogens, reproductive toxins, systemic toxins, asthmagens, pneumoconiotic agents, and sensitizers. In the workplace, exposure to chemical hazards is a type of occupational hazard. The use of protective personal equipment (PPE) may substantially reduce the risk of damage from contact with hazardous materials. Long-term exposure to chemical hazards such as silica dust, engine exhausts, tobacco smoke, and lead (among others) have been shown to increase risk of heart disease, stroke, and high blood pressure. Types of chemical hazard Routes of exposure The most common exposure route to chemicals in the work environment is th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell (biology)
The cell is the basic structural and functional unit of life forms. Every cell consists of a cytoplasm enclosed within a membrane, and contains many biomolecules such as proteins, DNA and RNA, as well as many small molecules of nutrients and metabolites.Cell Movements and the Shaping of the Vertebrate Body in Chapter 21 of Molecular Biology of the Cell '' fourth edition, edited by Bruce Alberts (2002) published by Garland Science. The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sebaceous
A sebaceous gland is a microscopic exocrine gland in the skin that opens into a hair follicle to secrete an oily or waxy matter, called sebum, which lubricates the hair and skin of mammals. In humans, sebaceous glands occur in the greatest number on the face and scalp, but also on all parts of the skin except the palms of the hands and soles of the feet. In the eyelids, meibomian glands, also called tarsal glands, are a type of sebaceous gland that secrete a special type of sebum into tears. Surrounding the female nipple, areolar glands are specialized sebaceous glands for lubricating the nipple. Fordyce spots are benign, visible, sebaceous glands found usually on the lips, gums and inner cheeks, and genitals. Structure Location Sebaceous glands are found throughout all areas of the skin, except the palms of the hands and soles of the feet. There are two types of sebaceous glands, those connected to hair follicles and those that exist independently. Sebaceous glands are found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sweat Gland
Sweat glands, also known as sudoriferous or sudoriparous glands, , are small tubular structures of the skin that produce sweat. Sweat glands are a type of exocrine gland, which are glands that produce and secrete substances onto an epithelial surface by way of a duct. There are two main types of sweat glands that differ in their structure, function, secretory product, mechanism of excretion, anatomic distribution, and distribution across species: * Eccrine sweat glands are distributed almost all over the human body, in varying densities, with the highest density in palms and soles, then on the head, but much less on the trunk and the extremities. Its water-based secretion represents a primary form of cooling in humans. * Apocrine sweat glands are mostly limited to the axillae (armpits) and perineal area in humans. They are not significant for cooling in humans, but are the sole effective sweat glands in hoofed animals, such as the camels, donkeys, horses, and cattle. Ceruminou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blood Vessels
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away from the tissues. Blood vessels are needed to sustain life, because all of the body's tissues rely on their functionality. There are five types of blood vessels: the arteries, which carry the blood away from the heart; the arterioles; the capillaries, where the exchange of water and chemicals between the blood and the tissues occurs; the venules; and the veins, which carry blood from the capillaries back towards the heart. The word ''vascular'', meaning relating to the blood vessels, is derived from the Latin ''vas'', meaning vessel. Some structures – such as cartilage, the epithelium, and the lens and cornea of the eye – do not contain blood vessels and are labeled ''avascular''. Etymology * artery: late Middle English; from Latin ' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Substance
Ground substance is an amorphous gel-like substance in the extracellular space that contains all components of the extracellular matrix (ECM) except for fibrous materials such as collagen and elastin. Ground substance is active in the development, movement, and proliferation of tissues, as well as their metabolism. Additionally, cells use it for support, water storage, binding, and a medium for intercellular exchange (especially between blood cells and other types of cells). Ground substance provides lubrication for collagen fibers. The components of the ground substance vary depending on the tissue. Ground substance is primarily composed of water and large organic molecules, such as glycosaminoglycans (GAGs), proteoglycans, and glycoproteins. GAGs are polysaccharides that trap water, giving the ground substance a gel-like texture. Important GAGs found in ground substance include hyaluronic acid, heparan sulfate, dermatan sulfate, and chondroitin sulfate. With the exception of hyalur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content. Collagen consists of amino acids bound together to form a triple helix of elongated fibril known as a collagen helix. It is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin. Depending upon the degree of mineralization, collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes one to two percent of muscle tissue and accounts for 6% of the weight of the skeletal muscle tissue. The fibroblast is the most common cell that crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fibroblasts
A fibroblast is a type of biological cell that synthesizes the extracellular matrix and collagen, produces the structural framework ( stroma) for animal tissues, and plays a critical role in wound healing. Fibroblasts are the most common cells of connective tissue in animals. Structure Fibroblasts have a branched cytoplasm surrounding an elliptical, speckled nucleus having two or more nucleoli. Active fibroblasts can be recognized by their abundant rough endoplasmic reticulum. Inactive fibroblasts (called fibrocytes) are smaller, spindle-shaped, and have a reduced amount of rough endoplasmic reticulum. Although disjointed and scattered when they have to cover a large space, fibroblasts, when crowded, often locally align in parallel clusters. Unlike the epithelial cells lining the body structures, fibroblasts do not form flat monolayers and are not restricted by a polarizing attachment to a basal lamina on one side, although they may contribute to basal lamina components in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skin Grafting
Skin grafting, a type of graft surgery, involves the transplantation of skin. The transplanted tissue is called a skin graft. Surgeons may use skin grafting to treat: * extensive wounding or trauma * burns * areas of extensive skin loss due to infection such as necrotizing fasciitis or purpura fulminans * specific surgeries that may require skin grafts for healing to occur - most commonly removal of skin cancers Skin grafting often takes place after serious injuries when some of the body's skin is damaged. Surgical removal (excision or debridement) of the damaged skin is followed by skin grafting. The grafting serves two purposes: reducing the course of treatment needed (and time in the hospital), and improving the function and appearance of the area of the body which receives the skin graft. There are two types of skin grafts: * The more common type involves removing a thin layer of skin from a healthy part of the body (the donor section) - like peeling a potato. * A full ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surgical Suture
A surgical suture, also known as a stitch or stitches, is a medical device used to hold body tissues together and approximate wound edges after an injury or surgery. Application generally involves using a needle with an attached length of thread. There are numerous types of suture which differ by needle shape and size as well as thread material and characteristics. Selection of surgical suture should be determined by the characteristics and location of the wound or the specific body tissues being approximated. In selecting the needle, thread, and suturing technique to use for a specific patient, a medical care provider must consider the tensile strength of the specific suture thread needed to efficiently hold the tissues together depending on the mechanical and shear forces acting on the wound as well as the thickness of the tissue being approximated. One must also consider the elasticity of the thread and ability to adapt to different tissues, as well as the memory of the threa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Migration
Cell migration is a central process in the development and maintenance of multicellular organisms. Tissue formation during embryonic development, wound healing and immune responses all require the orchestrated movement of cells in particular directions to specific locations. Cells often migrate in response to specific external signals, including chemical signals and mechanical signals. Errors during this process have serious consequences, including intellectual disability, vascular disease, tumor formation and metastasis. An understanding of the mechanism by which cells migrate may lead to the development of novel therapeutic strategies for controlling, for example, invasive tumour cells. Due to the highly viscous environment (low Reynolds number), cells need to continuously produce forces in order to move. Cells achieve active movement by very different mechanisms. Many less complex prokaryotic organisms (and sperm cells) use flagella or cilia to propel themselves. Eukaryot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epithelium
Epithelium or epithelial tissue is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. It is a thin, continuous, protective layer of compactly packed cells with a little intercellular matrix. Epithelial tissues line the outer surfaces of organs and blood vessels throughout the body, as well as the inner surfaces of cavities in many internal organs. An example is the epidermis, the outermost layer of the skin. There are three principal shapes of epithelial cell: squamous (scaly), columnar, and cuboidal. These can be arranged in a singular layer of cells as simple epithelium, either squamous, columnar, or cuboidal, or in layers of two or more cells deep as stratified (layered), or ''compound'', either squamous, columnar or cuboidal. In some tissues, a layer of columnar cells may appear to be stratified due to the placement of the nuclei. This sort of tissue is called pseudostratified. All glands are made up of epithe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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