Support of the growth hormone-somatomedin system to facilitate healing
Article Abstract:
Research has shown that various biologically active molecules known as growth factors are important in the process of wound healing and normal tissue repair. When tissue damage occurs, these growth factors are released from the tissues and enter into the bloodstream from the damaged area, inducing an increase in cellular division of supporting tissue. Included in this group of sensitive tissues are the lining cells of vessels, and specific bone (osteoblasts) and cartilage (chondroblasts) cells responsible for new bone and cartilage formation. The mechanisms of tissue healing that involve growth hormone (GH) and related components are reviewed. Growth hormone, also called somatotropin, is released from the pituitary gland. In young people it is vital for normal growth, and variations in levels of the substance can lead to a wide range of clinical conditions ranging from dwarfism to gigantism. In adults, GH release is associated with mechanisms that build the body (anabolic functions). Release of GH can be stimulated by fasting, stress, ovulation, deep sleep and by factors that depress the production of glucocorticoids (a group of adrenal hormones involved in maintaining mineral balance). Release of GH from the pituitary is controlled by the hypothalamus, an area of the brain, through the release of other hormonal factors. One of these, somatostatin, is active in inhibiting the release of growth hormone. GH causes the liver and other target organs to produce a group of small peptides (small molecules made of amino acids) called somatomedins (SM), which are important tissue growth factors. Together, GH and somatomedins form an important physiologic system vital for growth and tissue repair. The mechanisms of release and control of the GH-SM system are discussed, including the vital roles of nutrition, sleep and stress in the process of healing. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Heart and Lung
Subject: Health
ISSN: 0147-9563
Year: 1990
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Physiological effects of tissue oxygenation on wound healing
Article Abstract:
The availability of oxygen to tissues plays an important role in the process of wound healing. When skin is damaged, swelling occurs, fibroblasts (a type of cell) grow, and blood vessels and connective tissue begin to grow. During the early inflammatory phase, the process of wound repair begins with the activation of enzymes and white blood cells which destroy bacteria and cause blood clot formation. Macrophages (cells that engulf debris) clear the wound of destroyed cellular material. The blood flow to the injured area increases, bringing nutritive substances to the damaged tissue. Macrophages also stimulate fibroblasts to secrete collagen, a type of protein that strengthens the tissues. New blood vessels are formed to continue the supply of nutrients to the wound. Although the mechanism is not well understood, the wound then begins to contract and tissue forms from the wound's edge. Within one to two days, the epithelial cell layer begins to form. Nutrition, the immune system, oxygen, blood volume, infection, immunosuppression (caused by drugs or disease) and a decrease in red blood cells are all influential factors in wound healing. Oxygen affects the production of collagen, epithelial cell growth, and the growth of blood vessels. A decrease in the volume of circulating blood and the concentration of red blood cells can compromise the amount of oxygen available for wound healing. Interventions to improve oxygenation and enhance wound healing include replacing reduced blood volume, monitoring fluids, watching for signs of infection, and monitoring the overall healing progress. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Heart and Lung
Subject: Health
ISSN: 0147-9563
Year: 1989
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Effect of backrest position on mixed venous oxygen saturation in patients with mechanical ventilation after coronary artery bypass surgery
Article Abstract:
Following heart surgery, a variety of positions for the recovering patient have been recommended for a number of reasons. A flat position for 24 hours has been recommended to assist heart function, while comfort is the primary consideration of other recommended procedures. The effect of several positions on the oxygen content of the blood has been studied. Thirty patients who had no complicating problems, such as respiratory disease, were positioned flat on their backs, or elevated 20 or 40 degrees following coronary bypass surgery. No differences in blood oxygen content were associated with posture, indicating that cardiovascular function was not harmed by backrest elevation. Similarly, there were no time-dependent effects on blood oxygen levels related to positioning. The study indicates that among patients who are up to 70 years old, have no lung disease, have appropriate respiratory support, and normal temperature and circulation, backrests may be elevated up to 40 degrees at six to nine and one half hours after coronary bypass surgery without adverse effects on oxygen levels. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: Heart and Lung
Subject: Health
ISSN: 0147-9563
Year: 1990
User Contributions:
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