Parasympathetic Nervous System

Definition

The parasympathetic nervous system is one of the two divisions of the autonomic nervous system, responsible for the body's resting, digesting, and restorative functions. It works in opposition to the sympathetic nervous system, promoting relaxation and conserving energy.

5 Must Know Facts For Your Next Test

1. The parasympathetic nervous system is often referred to as the 'rest and digest' system, as it promotes relaxation and conserves energy.
2. The parasympathetic nervous system is responsible for stimulating digestive processes, including salivation, gastric secretion, and intestinal motility.
3. Acetylcholine is the primary neurotransmitter of the parasympathetic nervous system, and it acts on cholinergic receptors.
4. Activation of the parasympathetic nervous system can lower heart rate, blood pressure, and breathing rate, and increase digestive activity.
5. Drugs that affect the parasympathetic nervous system, such as muscarinic agonists and antagonists, can have significant impacts on bodily functions.

Review Questions

• Explain the role of the parasympathetic nervous system in the context of the divisions of the autonomic nervous system.
  • The parasympathetic nervous system is one of the two divisions of the autonomic nervous system, the other being the sympathetic nervous system. While the sympathetic nervous system prepares the body for action and mobilizes energy, the parasympathetic nervous system is responsible for the body's resting, digesting, and restorative functions. The parasympathetic nervous system promotes relaxation, conserves energy, and stimulates digestive processes, such as salivation, gastric secretion, and intestinal motility. This division of the autonomic nervous system works in opposition to the sympathetic nervous system, maintaining the body's homeostasis and ensuring that it is in a state of rest and recovery when not under stress or threat.
• Describe how drugs that affect the parasympathetic nervous system can influence bodily functions.
  • Drugs that target the parasympathetic nervous system can have significant impacts on various bodily functions. Muscarinic agonists, which mimic the effects of the neurotransmitter acetylcholine, can stimulate parasympathetic activity and lead to increased salivation, lacrimation, urination, digestion, and other parasympathetic-mediated responses. Conversely, muscarinic antagonists, which block the action of acetylcholine, can inhibit parasympathetic function and result in decreased digestive activity, reduced salivation, and other effects. The ability of these drugs to modulate the parasympathetic nervous system makes them useful in the treatment of conditions such as overactive bladder, gastrointestinal disorders, and certain types of glaucoma, but they can also have unintended side effects due to their broad impact on the autonomic nervous system.
• Analyze the relationship between the parasympathetic nervous system and the sympathetic nervous system, and explain how their interplay is essential for maintaining homeostasis.
  • The parasympathetic and sympathetic nervous systems work in a complementary and antagonistic manner to maintain homeostasis within the body. The parasympathetic nervous system is responsible for the body's resting, digesting, and restorative functions, promoting relaxation and conserving energy. In contrast, the sympathetic nervous system prepares the body for action, increasing heart rate, blood pressure, and breathing rate, while diverting blood away from the digestive system. This interplay between the two divisions of the autonomic nervous system is essential for maintaining a delicate balance and allowing the body to respond appropriately to various stimuli and stressors. When the parasympathetic system is dominant, the body is in a state of rest and recovery, while the sympathetic system's dominance prepares the body for a fight-or-flight response. The ability of these two systems to work together, shifting the balance as needed, is crucial for the body to adapt to changing conditions and maintain homeostasis.

Related terms

Autonomic Nervous System: The autonomic nervous system controls involuntary bodily functions, including heart rate, breathing, digestion, and pupil dilation, and is divided into the sympathetic and parasympathetic nervous systems.

Sympathetic Nervous System: The sympathetic nervous system is the division of the autonomic nervous system that prepares the body for action, increasing heart rate, blood pressure, and breathing rate, and diverting blood away from the digestive system.

Cholinergic Receptors: Cholinergic receptors are the receptors that bind to the neurotransmitter acetylcholine, which is the primary neurotransmitter of the parasympathetic nervous system.