Structure and functions of sympathetic nervous system
The sympathetic nervous system (SNS) 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 SNS is involved in preparing the body for “fight or flight” responses, which involve physical activity and increased physiological arousal. The SNS is activated in response to stressful or dangerous situations, and it has several distinct structural and functional features.
Structure: The SNS is composed of a network of nerves that originate in the thoracic and lumbar regions of the spinal cord, known as the thoracolumbar region. The SNS nerves emerge from the spinal cord through the ventral roots and form a chain of ganglia located on either side of the spine. From these ganglia, the SNS nerves extend to various organs, muscles, and glands throughout the body.
Functions: The SNS has several important functions, which include:
- Regulation of cardiovascular system: The SNS 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.
- Regulation of respiratory system: The SNS can also affect the respiratory system by increasing breathing rate and volume, which can help to increase oxygen delivery to the body’s tissues.
- Regulation of gastrointestinal system: The SNS can decrease blood flow to the digestive organs, reduce digestive secretions, and decrease intestinal motility. This helps to divert blood flow and metabolic resources to more immediately important physiological functions.
- Regulation of metabolic rate: The SNS can increase metabolic rate by promoting the breakdown of glycogen and the release of glucose from the liver. This can provide additional energy to support physical activity and other physiological demands.
- Regulation of thermoregulation: The SNS can also play a role in regulating body temperature by constricting blood vessels in the skin to conserve heat, or dilating blood vessels to release heat.
Overall, the sympathetic nervous system is an important regulatory system that is involved in preparing the body for physical activity and increasing physiological arousal during stressful or dangerous situations. Dysfunctions of the SNS can lead to a range of neurological disorders, including hypertension, arrhythmia, and autonomic dysfunctions.
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