Physiology is the study of the normal function of the human body whereas pathophysiology is the study of abnormal or disordered function of the body. The pathophysiologic mechanism gives rise to signs and symptoms which can be observed and assessed by the nurse. On the basis of these observations the nurse can plan for appropriate interventions to deal with the problems. The skin and mucus membrane are the body’s first line of physiologic defence. Inflammation is the response of tissue to injury or infection. Stress is a universal phenomenon and all people experience stress. Stress is part of everyday living and it requires some sort of adjustment on the part of the individual. The ability to tolerate stress is not same in all the people. Some people can tolerate much greater stress than other do. Early identification of both physiological and psychological stressors is a major responsibility of the nurse. A healthy lifestyle plays a major role in preventing stress. Relaxation techniques are very effective to reduce stress and its adverse effects commonly used techniques include progressive muscle relaxation, meditation, breathing techniques, massage, music therapy and the use of humor.