THE PHYSIOLOGY OF EMOTIONAL BEHAVIOR
One of the most basic and important aspects of the study of emotion is the investigation of the various and widespread bodily changes which occur in the organism during emotional disturbance. The relationship of such bodily changes to the inclusive behavior patterns denoted by the term "emotions" is undoubtedly very complex. Few psychologists would deny that the role played by organic changes in emotional behavior is an essential and probably a basic one. One important contribution to the problem is to clarify the nature and principal characteristics of the typical organic changes associated with emotional excitement.
Among the more frequently mentioned of these organic responses are changes which take place in the circulatory system--specifically, in blood pressure, in pulse rate, in the force of the heart beat, and in the distribution of blood within the body (as when the constriction of peripheral blood vessels may force blood from outlying regions and from the limbs to the interior of the body). Of importance also are respiratory changes, such as changes in the rate of breathing, in the respiratory rhythm, and in the inspiration-expiration ratio (the ratio of inhalation time to exhalation time). During emotional excitation there also occur changes in the gastrointestinal tract, such as an inhibition of digestive peristalsis in fear and an increase in the tonus of the stomach muscles, together with an increase in the acidity of the stomach, which is thought to occur in anxiety. Basically important also is a variety of possible glandular reactions, such as the heightened activity of the liver and of the adrenal glands (i.e., the medulla or inner part of the glands) in fear and other types of emotional disturbance, and increased activity of the sweat glands known to be responsible for that reduction in the electrical resistance of the skin which has been variously named "psychogalvanic reflex," "galvanic skin reflex," and "electrodermal response." Notable too are changes in the tensionof the skeletal muscles and changes in blood chemistry