what is sympathetic & parasympathetic nervous system?
Answers
The Autonomic Nervous System (ANS) is divided into two functionally distinct divisions, the Sympathetic and the Parasympathetic Divisions. Each consists of nerves that control the activity of the heart, blood vessels, glands, and other organs containing smooth muscles. The ANS controls numerous body functions that we don't normally think about, such as heart rate, blood pressure, digestion, and perspiration.
The two divisions of the ANS act in opposition and balance with each other; excitation of one division results in a balanced inhibition of the other division. For example, the sympathetic division increases heart rate; the parasympathetic division decreases it. The relative activation of each division is dependent on demands posed by the environment. The parasympathetic division increases digestive activity; the sympathetic division decreases it. The Sympathetic Division of the ANS is responsible for mobilizing the body in response to situations that are threatening or otherwise exciting. It activates functions needed to energize what is called the fight-or-flight response, the preparation to attack or run from an enemy. We experience the sympathetic response with intense emotions such as fear, anger, and even ecstasy. The Parasympathetic Division of the ANS conserves the body's energy during times of relaxation and supports internal body functions, such as the digestion of food. Finally, it is important to note that the relative activation of each division is dependent on the individual's perception of an event. The sympathetic division will be activated when we perceive an event to be particularly threatening or exciting. The responses are therefore subject to differences across individual people.
A common example of the balancing act between the sympathetic and parasympathetic divisions of the autonomic nervous system occurs on the roadway. Imagine yourself driving calmly on the expressway on your way to work. Another car cuts in front of you without signaling and almost causes an accident. You notice that a physical reaction to this threatening situation occurs almost immediately. Your heart rate accelerates, heavy breathing sets in, you feel hot and sweaty, and your stomach is upset. You feel an intense mixture of fear and anger, and perhaps express the latter through gestures! This is your sympathetic activity energizing you to either fight or get out of the way. Settling back to the relaxed state you were in before this near-mishap takes some time, and you are still rattled by the experience by the time you get to work. This prolonged state of duress reflects the slower response of the parasympathetic division.
Autonomous nervous system is of two types
-Sympathetic
-Parasympathetic
Sympathetic helps in high blood pressure and whereas parasympathetic helps in lower down the high blood pressure. They works in a coordination to maintain BP.