Physiology of Emotion

The sympathetic system activates during emotional arousal, increasing heart rate, accelerating breathing, dilating pupils, and causing dry mouth. These physiological changes, known as the fight-or-flight reaction, prepare the body to respond to stress or danger by mobilizing energy and heightening alertness for immediate action and survival.

The amygdala is essential for processing emotions such as fear and aggression. Individuals with amygdala damage show impaired ability to recognize these emotions in others, highlighting its critical importance in social and emotional perception. This brain structure is fundamental to how we interpret and respond to emotionally significant events and social cues.

The left cerebral hemisphere is more active during positive emotions like happiness, while the right hemisphere is more active during negative emotions including sadness and anxiety. This hemispheric specialization reflects distinct neural pathways for processing emotional valence, intensity, and behavioral responses to different emotional states.

Elevated levels of cortisol, a stress hormone, heighten sensitivity to stress and anxiety. When cortisol increases during emotional arousal, it amplifies the body's stress response and can intensify feelings of worry, physiological tension, and overall emotional reactivity to environmental stressors.

Neurotransmitters modulate emotions through distinct mechanisms. Low serotonin levels are linked to aggression and mood disturbances, while dopamine is associated with pleasure and reward mechanisms. These chemical messengers regulate mood, motivation, emotional expression, and behavioral responses throughout the nervous system.

Oxytocin, often called the love hormone, fosters social bonding and feelings of trust between individuals. This hormone promotes attachment behaviors and emotional connection, playing a key role in affiliative relationships, social cohesion, and the formation of lasting emotional bonds with others.

The parasympathetic system promotes relaxation and recovery by restoring the body to a calm state after a stressful event. It counteracts sympathetic arousal by lowering heart rate, slowing breathing, and reducing physiological tension to facilitate rest, recovery, and emotional regulation after stress.