The parasympathetic system, also known as the parasympathetic nervous system or the craniosacral division, is a component of the autonomic nervous system (ANS) that regulates various bodily functions and maintains homeostasis. It operates alongside the sympathetic system, which the body's flight or fight response, to balance and counteract its effects.
The parasympathetic system primarily works to conserve energy, promote rest and relaxation, and promote the body's functionality during restful states. It is responsible for controlling several vital functions, such as digestion, reducing heart rate, lowering blood pressure, promoting digestion and nutrient absorption, constricting pupils, stimulating salivation, and enhancing sexual arousal and function.
This system is composed of nerve fibers originating from the brainstem and the sacral region of the spinal cord. These fibers primarily release the neurotransmitter acetylcholine (ACh) to communicate information between nerve cells and target organs or tissues.
Stimulation of the parasympathetic system occurs through the action of the vagus nerve, which sends signals to various organs, including the heart, lungs, digestive system, and urinary system. The response is typically characterized by a slowing down of these organs' activities, allowing the body to rest, recover, and maintain its internal equilibrium.
Understanding the parasympathetic system's function and balance with the sympathetic system is essential for studying various physiological processes and their interactions within the body. Dysfunction or imbalances in the parasympathetic system can lead to several health conditions, such as impaired digestion, bradycardia (abnormally slow heart rate), and other systemic dysregulations.
