Parasympathetic Division

Definition

The parasympathetic division is a part of the autonomic nervous system responsible for regulating involuntary bodily functions during restful states. It promotes a 'rest and digest' response, counteracting the effects of the sympathetic division, which is responsible for the 'fight or flight' response. The parasympathetic division plays a crucial role in maintaining homeostasis by reducing heart rate, increasing digestive activities, and facilitating energy conservation.

5 Must Know Facts For Your Next Test

1. The parasympathetic division primarily uses acetylcholine as its neurotransmitter to convey signals to target organs.
2. Activation of the parasympathetic division leads to decreased heart rate and increased activity in the digestive tract.
3. The parasympathetic response is often associated with relaxation and recovery after stress or exertion.
4. Organs such as the heart, lungs, and digestive system have specific parasympathetic innervation that helps regulate their functions.
5. The balance between the sympathetic and parasympathetic divisions is essential for maintaining overall health and proper physiological function.

Review Questions

• How does the parasympathetic division interact with the sympathetic division to maintain homeostasis in the body?
  • The parasympathetic division works in opposition to the sympathetic division to maintain homeostasis by regulating bodily functions during restful states. While the sympathetic division prepares the body for stress through increased heart rate and energy mobilization, the parasympathetic division promotes 'rest and digest' responses by slowing down heart rate and stimulating digestive activities. This balance ensures that when the body is under stress, it can effectively respond, and once that stressor has passed, it can return to a state of relaxation and recovery.
• What physiological changes occur when the parasympathetic division is activated?
  • When the parasympathetic division is activated, several physiological changes occur. Heart rate decreases as the body shifts towards a relaxed state. Digestive activities are stimulated, leading to increased secretion of digestive enzymes and enhanced intestinal movement. Blood vessels may also dilate, promoting increased blood flow to the digestive organs while redirecting energy away from muscles that would be engaged in 'fight or flight' situations. These changes support processes essential for recovery and energy conservation.
• Evaluate the implications of an overactive or underactive parasympathetic division on overall health.
  • An overactive parasympathetic division can lead to conditions like bradycardia (abnormally slow heart rate) or excessive salivation, which might hinder daily functioning. Conversely, an underactive parasympathetic division can result in stress-related disorders as the body remains in a heightened state of alertness without adequate recovery periods. Both conditions can disrupt homeostasis and increase vulnerability to health issues such as anxiety or gastrointestinal disorders. Understanding how these imbalances affect health highlights the importance of proper autonomic regulation for overall well-being.

Related terms

Sympathetic Division: The sympathetic division is the part of the autonomic nervous system that prepares the body for stressful or emergency situations by increasing heart rate, dilating airways, and inhibiting digestion.

Autonomic Nervous System: The autonomic nervous system is a component of the peripheral nervous system that controls involuntary physiological functions such as heart rate, blood pressure, and digestion.

Vagus Nerve: The vagus nerve is a key component of the parasympathetic division, responsible for transmitting signals between the brain and various organs to regulate functions like heart rate and digestion.