Sympathetic Nervous System

Definition

The sympathetic nervous system is a component of the autonomic nervous system that prepares the body for 'fight or flight' responses during stressful situations. It increases heart rate, dilates airways, and redirects blood flow to essential muscles, all of which are vital for quick reactions and survival. This system plays a crucial role in maintaining homeostasis by balancing the body's response to stress and regulating physiological processes, especially during times of high demand.

5 Must Know Facts For Your Next Test

1. The sympathetic nervous system is activated during stressful situations, leading to increased heart rate and respiratory rate to prepare the body for rapid action.
2. This system utilizes neurotransmitters like norepinephrine to relay signals that enhance blood flow to muscles while reducing blood flow to non-essential systems like digestion.
3. The activation of the sympathetic nervous system can lead to a temporary suppression of immune function as energy is redirected towards immediate survival.
4. It works in tandem with the parasympathetic nervous system, which helps calm the body after a stressful event, establishing a balance between these two systems.
5. Responses initiated by the sympathetic nervous system can have long-lasting effects on health if triggered too frequently or maintained for extended periods, leading to issues such as chronic stress.

Review Questions

• How does the sympathetic nervous system contribute to an animal's ability to respond to stress?
  • The sympathetic nervous system prepares an animal to respond effectively to stress by activating various physiological changes. When faced with a threat, it increases heart rate, dilates bronchioles for better oxygen intake, and redistributes blood flow away from non-essential functions towards muscles. These adaptations enable quicker reactions and enhance survival chances during emergencies.
• Discuss the interplay between the sympathetic and parasympathetic nervous systems in regulating homeostasis during periods of stress.
  • The sympathetic and parasympathetic nervous systems work together to maintain homeostasis. During stress, the sympathetic system activates the 'fight or flight' response, enhancing alertness and physical readiness. Once the threat has passed, the parasympathetic system takes over to promote relaxation and recovery, slowing heart rate and aiding digestion. This balance ensures that the body can respond appropriately to challenges without compromising overall function.
• Evaluate the long-term effects of chronic activation of the sympathetic nervous system on cardiovascular health.
  • Chronic activation of the sympathetic nervous system can lead to significant cardiovascular issues. Prolonged increases in heart rate and blood pressure place excessive strain on the heart and blood vessels. This can contribute to conditions such as hypertension, atherosclerosis, and even heart disease over time. Understanding this relationship emphasizes the importance of managing stress effectively to maintain cardiovascular health.

Related terms

Parasympathetic Nervous System: The parasympathetic nervous system is the other main division of the autonomic nervous system, responsible for 'rest and digest' activities that promote relaxation and energy conservation.

Homeostasis: Homeostasis refers to the process by which biological systems maintain stability while adjusting to conditions that are optimal for survival.

Neurotransmitters: Neurotransmitters are chemical messengers released by neurons to transmit signals across synapses, playing a key role in the communication within the nervous system, including those involved in sympathetic responses.