Sympathetic nervous system

Definition

The sympathetic nervous system is a part of the autonomic nervous system that prepares the body for 'fight or flight' responses during stressful situations. It activates processes that increase heart rate, dilate airways, and inhibit digestion, ensuring that energy is directed to essential functions needed for immediate survival. This system plays a crucial role in regulating bodily functions in response to perceived threats, connecting deeply with the mechanisms involved in digestion and overall bodily regulation.

5 Must Know Facts For Your Next Test

1. The sympathetic nervous system activates in response to stress, allowing quick reactions and increased alertness.
2. When the sympathetic nervous system is engaged, it diverts blood flow away from the digestive organs to muscles, enhancing physical performance.
3. It operates through a complex network of neurons that release neurotransmitters, such as norepinephrine, to stimulate target organs.
4. Stressful stimuli can lead to prolonged activation of the sympathetic nervous system, which may negatively impact digestive health by reducing digestive secretions.
5. The sympathetic nervous system has long-term implications on health, including contributing to conditions like irritable bowel syndrome (IBS) due to chronic stress responses.

Review Questions

• How does the sympathetic nervous system interact with digestive processes during stressful situations?
  • The sympathetic nervous system prioritizes immediate survival by diverting blood flow away from the digestive organs and towards muscles and vital systems during stressful situations. This response reduces digestive activity as energy is redirected for fight or flight actions. While this prepares the body for quick reactions, it can lead to decreased digestive efficiency and discomfort if stress is chronic.
• What are the physiological effects of sympathetic nervous system activation on other organ systems beyond digestion?
  • Activation of the sympathetic nervous system causes several physiological changes across multiple organ systems. For example, heart rate increases to pump more blood quickly to muscles, respiratory rates rise to provide more oxygen, and pupils dilate for improved vision. These changes collectively prepare the body to react swiftly to perceived threats while simultaneously inhibiting non-essential functions like digestion.
• Evaluate how chronic activation of the sympathetic nervous system could influence overall health and well-being.
  • Chronic activation of the sympathetic nervous system can lead to various health issues due to continuous stress responses. Long-term effects may include cardiovascular problems from persistent elevated heart rates and blood pressure, gastrointestinal disturbances like IBS due to reduced digestive function, and increased anxiety or mood disorders. This constant state of readiness can impair quality of life and overall well-being by disrupting normal physiological balance and leading to chronic health conditions.

Related terms

Parasympathetic Nervous System: The part of the autonomic nervous system that promotes 'rest and digest' activities, counterbalancing the effects of the sympathetic nervous system.

Autonomic Nervous System: The division of the peripheral nervous system that controls involuntary bodily functions, consisting of the sympathetic and parasympathetic systems.

Adrenaline: A hormone released by the adrenal glands during stress, enhancing the effects of the sympathetic nervous system by increasing heart rate and energy availability.