Physiological Responses to Injury

Physiological Responses to Injury

Andrew’s Note:  Today we present the another article in our Military Pedagogy series drawn from U.S. Army Subcourse MD0576, Wound Care [Approved For Public Release; Distribution is Unlimited].  Today’s article builds on our previous discussions of Wound Terminology  and Wound Healing and Complications by discussing Physiological Responses to Injury.  As we’ve previously discussed, military first aid and field medicine focuses almost entirely on stabilizing patients and moving them rapidly to the rear for further treatment. Needless to say, seek professional medical care immediately in the event of illness or injury and take action yourself only if you have been properly trained.  This series focusing on first aid will run through the weekend and we’ll start Monday with a guest author who’s written an article I’m really excited about.

Physiological Responses to Injury

Once the skin and tissue have been injured, the process of healing begins.  Many factors influence the body’s ability to grow new tissue.

Age. Very young and very old people heal more slowly than those in other age groups. People in these age groups have less ability to fight infection, and fighting infection is a major part of the healing process. The endocrine functions in infants are sluggish, and infants have limited reserves of fat, glycogen, and extracellular water–all which are necessary to fight infection. Healing is slower in the elderly because cardiovascular, renal, pulmonary, and musculoskeletal functions may be slowed down by chronic disease or perhaps just by the wearing out of body parts.

Figure 1-1 AbrasionMalnutrition

Malnourishment and obesity, both forms of malnutrition, affect wound healing. A person who is undernourished has less fat and carbohydrate reserve; therefore, body protein (necessary for wound healing) must be used to provide energy needed for basic metabolic functions. This results in an imbalance of nitrogen which in turn depresses fibroblastic synthesis of collagen, the connective tissue for scar formation. A person suffering from Vitamin C deficiency may not be able to produce fibroblast causing a delay in wound healing. In obese individuals, fatty tissue may keep foreign matter from being seen. Fatty tissue has relatively few blood vessels, causing such tissue to separate easily. Tissue which separates easily heals slowly.

Abnormalities in Endocrine Function

Healing is slower if there are such abnormalities. In a person suffering from chronic vascular changes, the injured tissues of the wound may not get enough blood to heal at a normal rate. Persons having corticosteroid therapy will find that wounds heal more slowly.

Hormone Production and Carbohydrate Metabolism

The combined effect of the increased hormone production is to increase the metabolism of carbohydrates.  The metabolism of carbohydrates is important in the body’s response to trauma. If the body’s store of carbohydrates is depleted (severe crush injuries, starvation), the body will begin to use fats and proteins in place of carbohydrates. Eventually, there will not be enough carbohydrates to aid in the healing process.

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