Wilderness and Rescue Medicine 7th Edition Jeffrey Isaac, PA-C and David E. Johnson, MD

Glossary 258

guarding Protective tightening of the abdomi- nal wall muscles in response to the pressure of abdominal palpation. Can be voluntary or invol- untary. closed head injury Injury to the brain. Also called concussion. heart attack Heart muscle ischemia caused by a blood clot or spasm of the coronary arteries or by an arrhythmia, resulting in the necrosis (or infarction) of heart tissue. heat challenge Combined effects of ambient tem- perature and metabolic activity that contribute to body heating. heat exhaustion State of fatigue related to heat stress. May or may not include dehydration. heat response The normal body response to the heat challenge, including sweating and vasodila- tion of the shell. heat stroke Severe elevation of body temperature (over 105° F). hemoglobin Molecule contained within red blood cells that binds to oxygen during its trans- port to body cells. hemothorax Blood in the chest cavity as a result of injury, usually collecting between the chest wall and lung tissue. hemotoxin Toxins that destroy body cells, caus- ing inflammation, pain, and swelling. Also called tissue toxins. high-altitude cerebral edema (HACE) The accumulation of fluid in brain tissue due to hypox- ia at altitude, capable of producing elevated intra- cranial pressure. histamine Hormone released by various pro- cesses causing, among other effects, vasodilation and bronchoconstriction.

hollow organs The stomach, intestines, bladder, and other organs enclosing space occupied by fluid and/or gas. hormones Chemical compounds released by glands to have specific effects of specific body tissues. hyperextension To extend a joint beyond its nor- mal range of motion. hyperventilation syndrome Respiratory alkalo- sis. The nervous system symptoms of numbness, visual field contraction, and light-headedness caused by reduced carbon dioxide in the blood due to excessive ventilation, usually associated with acute stress reaction. hypodermoclysis Injecting IV fluid, usually nor- mal saline, into the subcutaneous space where it can be absorbed by the circulatory system. hypoglycemia A condition characterized by a low blood glucose level, capable of causing brain failure. hyponatremia A condition in which the body has insufficient sodium and other salts, usually because of excess water intake. hypothermia Low body core temperature. hypoxia Lack of oxygen. infarction Tissue death; also called necrosis. infection Pathologic colonization of body tis- sues by bacteria, virus, fungus, or other micro- organisms. inflammation A generic body response to illness or injury resulting in redness, swelling, warmth, and tenderness. intoxication Altered level of consciousness or mental status due to the influence of chemicals such as drugs, alcohol, and inhaled gasses.