Structure and functions of parasympathetic nervous system.
The parasympathetic nervous system (PNS) is one of the two main divisions of the autonomic nervous system (ANS), which is responsible for controlling the involuntary functions of the body. The PNS is involved in regulating the body’s “rest and digest” responses, which involve restful activities and decreased physiological arousal. The PNS has several distinct structural and functional features.
Structure: The PNS is composed of a network of nerves that originate in the brainstem and the sacral region of the spinal cord, known as the craniosacral region. The PNS nerves emerge from the brainstem and sacral region through the cranial nerves and sacral spinal nerves, respectively. The PNS nerves extend to various organs, muscles, and glands throughout the body.
Functions: The PNS has several important functions, which include:
- Regulation of cardiovascular system: The PNS plays a critical role in regulating heart rate, blood pressure, and blood vessel diameter, which are all important for maintaining adequate blood flow to the body’s organs and tissues. The PNS helps to slow down the heart rate and reduce blood pressure during restful activities.
- Regulation of respiratory system: The PNS can also affect the respiratory system by decreasing breathing rate and volume during restful activities.
- Regulation of gastrointestinal system: The PNS can increase blood flow to the digestive organs, promote digestive secretions, and increase intestinal motility. This helps to support the body’s digestion and absorption of nutrients during restful activities.
- Regulation of metabolic rate: The PNS can decrease metabolic rate by promoting energy storage and conservation. This can help to support restful activities and conserve energy.
- Regulation of thermoregulation: The PNS can also play a role in regulating body temperature by increasing blood flow to the skin to release heat, or reducing blood flow to conserve heat.
Overall, the parasympathetic nervous system is an important regulatory system that is involved in promoting restful activities and reducing physiological arousal. Dysfunctions of the PNS can lead to a range of neurological disorders, including autonomic dysfunctions, gastrointestinal disorders, and cardiovascular disorders.
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