The pericardium is the heart's protective sack. It is regarded in Chinese medicine as a Fire-energy organ whose special function is to protect the heart. Not only does the pericardium provide the heart with physical protection, its energy also protects the heart from damage and disruption by excessive emotional energies generated by the other organs, such as anger from the liver, fear from the kidneys, and grief from the lungs. In the Chinese system of health, extreme outbursts of the Seven Emotions are regarded as powerful disruptors of internal energy balance and major causes of disease. Without the pericardium to protect it, the heart would be subject to injury from the radical fluctuations in energy caused by every emotional up and down of the day.