... small-diameter myelinated A-delta (Aδ) and the unmyelinated (C fiber) axons (Fig. 12 -1). These fibers are present in nerves to the skin and to deep somatic and visceral structures. Some tissues, ... sensation and emotion. When acute, pain is characteristically associated with behavioral arousal and a stress response consisting of increased blood pressure, heart rate, pupil diameter, and plasma ... tissue damage, the quality, time course, and location of a patient's pain complaint and the location of tenderness provide important diagnostic clues and are used to evaluate the response...