Sympathetic Nervous System

Definition

The sympathetic nervous system is a division of the autonomic nervous system responsible for the body's immediate physiological response to stressful or emergency situations. It prepares the body for the 'fight-or-flight' response by increasing heart rate, blood pressure, and respiration rate, while also diverting blood flow away from the digestive system.

5 Must Know Facts For Your Next Test

1. The sympathetic nervous system originates in the thoracic and lumbar regions of the spinal cord and its nerve fibers innervate almost all organs and tissues in the body.
2. Activation of the sympathetic nervous system triggers the release of the hormones epinephrine (adrenaline) and norepinephrine (noradrenaline) from the adrenal glands.
3. These hormones increase heart rate, blood pressure, and blood glucose levels, while also diverting blood flow away from the digestive system and towards the muscles, lungs, and brain.
4. The sympathetic nervous system plays a crucial role in the body's 'fight-or-flight' response, preparing the body to either confront a stressful situation or flee from it.
5. Chronic activation of the sympathetic nervous system can lead to various health issues, such as high blood pressure, heart disease, and anxiety disorders.

Review Questions

• Explain the relationship between the sympathetic nervous system and the adrenal glands in the context of the body's stress response.
  • The sympathetic nervous system and the adrenal glands work together to mediate the body's response to stress. When the sympathetic nervous system is activated, it triggers the release of hormones, such as epinephrine and norepinephrine, from the adrenal glands. These hormones then act on various organs and tissues to prepare the body for the 'fight-or-flight' response, increasing heart rate, blood pressure, and blood glucose levels, while also diverting blood flow away from the digestive system. This integrated response allows the body to quickly mobilize resources to deal with the stressful situation.
• Describe how the sympathetic nervous system's functions differ from those of the parasympathetic nervous system, and explain the importance of this division within the autonomic nervous system.
  • The sympathetic and parasympathetic nervous systems have opposing functions within the autonomic nervous system. While the sympathetic nervous system is responsible for the body's 'fight-or-flight' response, the parasympathetic nervous system is involved in the 'rest and digest' functions, promoting activities like digestion, urination, and sexual arousal. This division allows the body to maintain a delicate balance between the two states, ensuring that it can quickly respond to stressful situations while also conserving energy and resources for essential bodily functions. The ability to switch between these two modes is crucial for maintaining homeostasis and overall health.
• Analyze the potential long-term consequences of chronic activation of the sympathetic nervous system, and discuss strategies that could be used to mitigate these effects.
  • Chronic activation of the sympathetic nervous system, often due to persistent stress, can have detrimental long-term effects on the body. Prolonged release of hormones like epinephrine and norepinephrine can lead to issues such as high blood pressure, heart disease, and anxiety disorders. To mitigate these effects, it is important to implement stress management techniques, such as regular exercise, mindfulness practices, and relaxation methods. Additionally, addressing the underlying causes of chronic stress, whether they are environmental, psychological, or physiological, can help reduce sympathetic nervous system activation and its associated health risks. By maintaining a balance between the sympathetic and parasympathetic nervous systems, individuals can better regulate their stress response and promote overall well-being.

Related terms

Autonomic Nervous System: The autonomic nervous system is the part of the nervous system that controls involuntary bodily functions, such as heart rate, blood pressure, respiration, digestion, and temperature regulation.

Parasympathetic Nervous System: The parasympathetic nervous system is the opposing division of the autonomic nervous system, responsible for the body's 'rest and digest' functions, promoting activities like digestion, urination, and sexual arousal.

Adrenal Glands: The adrenal glands are endocrine glands that sit atop the kidneys and secrete hormones, including adrenaline and cortisol, that play a crucial role in the body's stress response mediated by the sympathetic nervous system.