The Physiology of Emotions

May 22, 2013


by Kady Babs

We often feel pressure in our bodies as a result of strong emotional experiences. When we are embarrassed we describe it as a “blush” and during intense anger we refer to a “pounding” in the temples. Most often people report a ‘knot” in the stomach when frightened, and when they nervous they experience “butterflies”. These are the simple extreme examples from the common man’s experiences. There are, of course, a number of physiological changes that take place during emotions.

Emotions and the Autonomic Nervous System

The Autonomic Nervous System (ANS) regulates the body’s internal environment and usually functioning without conscious control. It has two divisions, the sympathetic and the parasympathetic. Both have broadly the opposite effects. The sympathetic division dominates during emergency or stress and promotes energy expenditure.

The Sympathetic Nervous System (SNS) encourages the increase of blood sugar, heart heat and blood pressure required for sustained physical activity. But at the same time it inhibits the process of digestion. On the contrary the PNS (Parasympathetic Nervous System) dominates during relaxation and promotes energy conservation, it brings down the heartbeat rate and blood flow to the skeletal muscles also promoting digestion. Most of the physiological changes associated with strong emotion such as intense fear and anger are caused by activation of the parasympathetic division.

Brain Structure and Emotion


The ANS mainly triggers the physiological changes in emotions. The ANS is coordinated by the brain. The hypothalamus, in particular, and some areas of the limbic system are involved in a number of emotional reactions, such as anger, fear and aggression.

In cases of exaggerated emotional behaviour in human beings, damage to certain limbic areas was found. Such damage can take place before, during or just after birth. It can arise from a variety of causes including diseases affecting brain. Drug abuse, trauma due to auto accident, athletic injuries or gunshot wounds also cause such damages. Charles Whitman of University of Texas was the man who killed his wife and mother one night. Next morning he climbed to top of campus tower with a powerful rifle with telescopic sight. From there he proceeded to fire at every thing that moved. After one and half hour when he was finally shot down by the police he had killed 38 people. Although he had received psychiatric treatment for the last many months, an autopsy revealed a malignant tumor on the amygdala, part of the limbic system.

Psychologists believed that brain’s control over emotions was largely through hypothalamus and amygdala but recently it has become clear that cerebral cortex is initially involved as well. The most interesting discovery is that the cortex’s role in emotion is asymmetrical. That is the left side contributes more to positive feelings while the right side contributes more to the negative ones. Those who suffer extensive damage to the right cerebral hemisphere are often quite acid and dare free in mood. That means that euphoric emotions are greatly influenced by left brain activity. Injury to right brain may serve to dis-inhibit or let free.

Image Credit: Natalie Jordan