The autonomic nervous system has two divisions. Which is correct?

The autonomic nervous system has two divisions. Which is correct?

• A. Somatic nervous system and visceral nervous system
• B. Sympathetic division and parasympathetic division
• C. Cranial division and spinal division
• D. Enteric nervous system and autonomic nervous system

Answer: (B)

The autonomic nervous system is organized into two divisions that regulate most involuntary functions by often acting in opposition to fine-tune organ activity. One division prepares the body for action—heart rate rises, airway passages open, pupil size increases, and energy stores become available—classic fight-or-flight responses. The other division promotes rest and maintenance—slowing the heart, supporting digestion, and conserving energy. These divisions originate from different parts of the central nervous system: the sympathetic division mainly from the thoracic and lumbar spinal levels, and the parasympathetic division from the brainstem and sacral spinal levels. Because most organs receive input from both divisions, they can be modulated to meet the body's needs in different situations, providing coordinated control of involuntary functions.

The autonomic nervous system is organized into two divisions that regulate most involuntary functions by often acting in opposition to fine-tune organ activity. One division prepares the body for action—heart rate rises, airway passages open, pupil size increases, and energy stores become available—classic fight-or-flight responses. The other division promotes rest and maintenance—slowing the heart, supporting digestion, and conserving energy. These divisions originate from different parts of the central nervous system: the sympathetic division mainly from the thoracic and lumbar spinal levels, and the parasympathetic division from the brainstem and sacral spinal levels. Because most organs receive input from both divisions, they can be modulated to meet the body's needs in different situations, providing coordinated control of involuntary functions.