Autonomic nervous system

Definition

The autonomic nervous system (ANS) is a component of the peripheral nervous system responsible for regulating involuntary bodily functions, including heart rate, digestion, and respiratory rate. It operates automatically and consists of two main divisions: the sympathetic and parasympathetic systems, which work together to maintain homeostasis and respond to stressors.

5 Must Know Facts For Your Next Test

1. The autonomic nervous system plays a crucial role in regulating the gastrointestinal system by controlling peristalsis, enzyme secretion, and blood flow to digestive organs.
2. Both sympathetic and parasympathetic branches interact to modulate gastrointestinal function, where sympathetic activation can inhibit digestion while parasympathetic activation enhances it.
3. Neurotransmitters like acetylcholine and norepinephrine are essential in transmitting signals within the autonomic nervous system, influencing how digestive organs respond.
4. The autonomic nervous system operates without conscious control, allowing for continuous regulation of bodily functions even when a person is unaware.
5. Stress can significantly impact gastrointestinal function through the autonomic nervous system by triggering sympathetic responses that may lead to issues like decreased appetite or digestive problems.

Review Questions

• How does the autonomic nervous system influence gastrointestinal function during stress?
  • During stress, the sympathetic nervous system activates the 'fight or flight' response, which can divert blood flow away from the gastrointestinal tract and inhibit digestive processes. This response is designed to prepare the body for immediate action rather than digestion. Consequently, stress can lead to symptoms such as decreased appetite and slower digestion due to reduced activity in the enteric nervous system.
• Discuss how the balance between the sympathetic and parasympathetic divisions of the autonomic nervous system regulates digestion.
  • The balance between the sympathetic and parasympathetic divisions is critical for proper digestion. The parasympathetic division promotes 'rest and digest' activities by stimulating saliva production, increasing gastric secretions, and enhancing peristalsis. In contrast, when the sympathetic division is activated, it inhibits these processes to prioritize energy use for immediate physical demands. This dynamic interplay ensures that digestion occurs optimally under varying conditions.
• Evaluate the significance of neurotransmitters in the autonomic nervous system's regulation of gastrointestinal functions.
  • Neurotransmitters like acetylcholine and norepinephrine are vital for communication within the autonomic nervous system, significantly impacting gastrointestinal functions. Acetylcholine is primarily involved in stimulating digestive activities such as enzyme secretion and muscle contractions in the gut. Conversely, norepinephrine can inhibit these functions during sympathetic activation. Understanding these neurotransmitter roles helps illustrate how the autonomic nervous system precisely controls digestive processes in response to internal and external stimuli.

Related terms

Sympathetic Nervous System: The division of the autonomic nervous system that prepares the body for 'fight or flight' responses during stressful situations, increasing heart rate and energy mobilization.

Parasympathetic Nervous System: The division of the autonomic nervous system that promotes 'rest and digest' activities, slowing the heart rate and enhancing digestive processes.

Enteric Nervous System: A subdivision of the autonomic nervous system that specifically governs gastrointestinal function, often referred to as the 'second brain' due to its ability to operate independently.