Parasympathetic division

Definition

The parasympathetic division is a part of the autonomic nervous system that promotes a 'rest and digest' response, counteracting the effects of the sympathetic division. This system is responsible for stimulating activities that occur when the body is at rest, such as digestion, urination, and conserving energy. It plays a crucial role in maintaining homeostasis by regulating bodily functions when the body is not under stress.

5 Must Know Facts For Your Next Test

1. The parasympathetic division is mainly mediated by the neurotransmitter acetylcholine, which helps slow heart rate and increase digestive activities.
2. It includes cranial nerves like the vagus nerve, which innervates many organs in the body, including the heart, lungs, and digestive tract.
3. The activation of the parasympathetic division leads to physiological changes such as increased salivation, lacrimation (tear production), urination, digestion, and defecation.
4. This division works to conserve energy by slowing down metabolism and facilitating recovery after stress or physical exertion.
5. The overall effect of parasympathetic activation is often described as a calming influence on the body, promoting relaxation and recovery.

Review Questions

• How does the parasympathetic division interact with the sympathetic division to regulate bodily functions?
  • The parasympathetic division works in tandem with the sympathetic division to maintain balance within the body. While the sympathetic division activates 'fight or flight' responses during stress or danger, increasing heart rate and energy mobilization, the parasympathetic division counteracts these effects by promoting 'rest and digest' functions. This interplay ensures that bodily systems can respond appropriately to different situations, allowing for both immediate reactions and long-term stability.
• Discuss the role of acetylcholine in the functioning of the parasympathetic division and its impact on heart rate and digestion.
  • Acetylcholine is the primary neurotransmitter used by the parasympathetic division to signal various target organs. When released, it binds to receptors in the heart to decrease heart rate and promote relaxation. Additionally, acetylcholine stimulates digestive glands and smooth muscles in the gastrointestinal tract, enhancing digestive processes. This dual action underscores how acetylcholine supports homeostasis by promoting calmness in bodily functions.
• Evaluate how an imbalance between the sympathetic and parasympathetic divisions can affect health outcomes.
  • An imbalance between the sympathetic and parasympathetic divisions can lead to various health issues. For instance, chronic activation of the sympathetic division due to prolonged stress can result in hypertension, anxiety disorders, and digestive problems. Conversely, an underactive parasympathetic response may impair recovery processes and lead to issues like poor digestion and fatigue. Understanding this balance is essential for managing stress-related health outcomes and ensuring optimal functioning of bodily systems.

Related terms

Sympathetic Division: The part of the autonomic nervous system that prepares the body for 'fight or flight' responses during stressful situations, increasing heart rate and energy availability.

Autonomic Nervous System:

A self-regulating system that controls involuntary bodily functions, including heart rate, blood pressure, and digestion, through its sympathetic and parasympathetic divisions.

Homeostasis:

The state of steady internal conditions maintained by biological systems, including the balance of physiological processes governed by the autonomic nervous system.