Neuromuscular system: Sympathetic and parasympathetic.

The idea

The autonomic nervous system controls involuntary body functions and has two divisions that usually oppose each other. The sympathetic division prepares the body for activity or stress, often called the fight-or-flight response: heart rate and breathing rate increase, the airways widen, blood is redirected towards working skeletal muscle, and glucose is released for energy. The parasympathetic division dominates at rest and supports recovery and digestion: heart rate and breathing rate decrease, the airways narrow, and blood flow is directed towards the digestive system. During a football match, the sympathetic division raises heart rate as play begins, while after the final whistle the parasympathetic division slows the heart and supports recovery.

What earns the marks

• The autonomic nervous system controls involuntary functions and is divided into sympathetic and parasympathetic branches.
• The sympathetic division prepares the body for activity or stress by increasing heart rate, increasing breathing rate and widening the airways.
• Sympathetic activity redirects blood flow towards working skeletal muscle and promotes the release of glucose to supply energy.
• The parasympathetic division dominates during rest and recovery, slowing heart rate and breathing rate and supporting digestion.
• The two divisions generally have opposing effects on the same organs, allowing the body to switch between activity and recovery.
• A correct sporting sequence is: exercise begins, sympathetic activity raises heart rate and breathing rate, exercise ends, parasympathetic activity slows heart rate and breathing rate.

Common mistakes and how to put them right

• Reversing the two divisions.

  Put it right: The sympathetic division prepares the body for activity, while the parasympathetic division supports rest, digestion and recovery.

• Thinking the autonomic nervous system is under conscious control.

  Put it right: It controls involuntary functions such as heart rate and digestion.

• Believing the sympathetic division only ever increases activity in every organ.

  Put it right: It increases heart rate and breathing rate but reduces activity in the digestive system.

• Assuming the parasympathetic division stops the heart or breathing.

  Put it right: It slows heart rate and breathing rate rather than stopping them.

Exam tips

• Link each division to a clear situation: sympathetic for exercise or stress, parasympathetic for rest and recovery.
• Use paired effects on the same organ, such as heart rate increasing under sympathetic activity and decreasing under parasympathetic activity.
• When a question gives a sporting scenario, name the division that dominates and then state two specific effects on the body.
• Avoid vague answers such as 'it calms you down'; name the organ and the change, for example heart rate decreases.