Medical term referring to the heart and blood vessels. Synonymous with 循環系 (じゅんかんけい).
See also: 循環系
Diseases of the circulatory system are closely related to lifestyle habits.
循環器 refers to an individual organ involved in circulation (e.g. the heart), while 循環器系 refers to the entire circulatory system as a whole.
Compound of 循環器 (じゅんかんき, 'circulatory organ') + 系 (けい, 'system').