Emotion (affect) - feelings that involve subjective evaluation, physiological process and cognitive beliefs. Mood - diffuse and long-lasting emotional states that influence rather than interrupt thought and behaviour. Reflects perceptions of whether have the personal resources necessary to meet environmental demands. Stress - a pattern of behavioural and physiological responses to events that match or exceed an organism"s abilities. Health physiology is the field of concerned with the events that affect physical well- being. Negative and positive experiences guide behaviour that increases the probability of surviving and reproducing. Emotions/emotional responses are adaptive because they prepare and guide behaviors. Provide information about the importance of stimuli to personal goals and then prepare people for actions aimed at helping achieve those goals. At birth, infant can display: joy, interest, disgust, and pain. Lower half of face more important than upper half of face in communicating emotion.