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 various physiological changes such as increased heart rate, dilation of pupils, and energy mobilization to enhance the body’s ability to respond to perceived threats. This system plays a crucial role in maintaining homeostasis by balancing the body's responses to stressors with its overall functioning.

5 Must Know Facts For Your Next Test

1. The sympathetic nervous system is activated during stressful situations, which triggers the release of hormones like adrenaline and norepinephrine.
2. It increases heart rate and blood pressure, redistributing blood flow from non-essential organs to muscles, enhancing physical performance.
3. The sympathetic response can lead to physiological changes such as increased respiratory rate, sweating, and reduced digestive activity.
4. This system works in conjunction with the parasympathetic nervous system to maintain balance in bodily functions during different states of stress and relaxation.
5. Chronic activation of the sympathetic nervous system can lead to negative health outcomes such as anxiety, high blood pressure, and cardiovascular disease.

Review Questions

• How does the sympathetic nervous system contribute to homeostasis during stressful events?
  • During stressful events, the sympathetic nervous system triggers a series of responses that prepare the body for immediate action. This includes increasing heart rate and redirecting blood flow to muscles while decreasing functions that are not vital for survival, such as digestion. By doing this, it allows the body to respond effectively to threats while also maintaining a level of internal stability that is essential for survival.
• Discuss the role of neurotransmitters in the functioning of the sympathetic nervous system.
  • Neurotransmitters are crucial for the functioning of the sympathetic nervous system, with norepinephrine being a key player. When activated, neurons release norepinephrine into target organs, leading to increased heart rate, blood vessel constriction, and other fight or flight responses. This rapid communication via neurotransmitters ensures that the body can quickly adapt to stressful situations and maintain necessary physiological changes for survival.
• Evaluate the impact of chronic activation of the sympathetic nervous system on overall health.
  • Chronic activation of the sympathetic nervous system can have detrimental effects on overall health. When this system is persistently engaged due to ongoing stress, it may lead to conditions such as hypertension, anxiety disorders, and increased risk of cardiovascular diseases. This prolonged state can disrupt normal homeostatic mechanisms and create an imbalance in bodily functions, highlighting the importance of managing stress effectively to maintain long-term health.

Related terms

Parasympathetic Nervous System: The part of the autonomic nervous system that promotes the 'rest and digest' functions, helping to conserve energy and restore the body to a state of calm.

Homeostasis: The process by which the body maintains a stable internal environment despite external changes, involving various regulatory mechanisms including those from the autonomic nervous system.

Neurotransmitters: Chemical messengers released by neurons that transmit signals across synapses in the nervous system; norepinephrine is a key neurotransmitter used by the sympathetic nervous system.