The part of the nervous system that controls involuntary bodily functions such as heart rate, digestion, breathing, and glandular secretions. It operates largely below the level of consciousness and is divided into sympathetic and parasympathetic branches.
From Greek autonomos meaning 'self-governing' (auto- 'self' + nomos 'law'), coined in the late 19th century. The term reflects how this system operates independently of conscious control, governing itself according to the body's internal needs.
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